Species Recorded | Taxon | Scientific Name | Common Name | Records | Latest |
| alder fly, lacewing or snake fly | Hemerobius | a Hemerobius species (unidentified) | 6 | 2018 |
| alder fly, lacewing or snake fly | Hemerobius humulinus | a brown lacewing | 12 | 2016 |
| alder fly, lacewing or snake fly | Hemerobius lutescens | a brown lacewing | 14 | 2009 |
| alder fly, lacewing or snake fly | Hemerobius micans | a brown lacewing | 10 | 2023 |
| alder fly, lacewing or snake fly | Hemerobius stigma | a brown lacewing | 1 | 2009 |
| algae or stonewort | Himanthalia elongata | Thongweed | 2 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Halictinae | a Halictinae species (unidentified) | 5 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Halictus rubicundus | a solitary bee | 35 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Halictus tumulorum | Bronze Furrow Bee | 43 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Halticoptera flavicornis | a chalcid wasp | 1 | 2009 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Harpactus tumidus | a solitary wasp | 1 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hedychridium roseum | a rubytail wasp | 1 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hemiteles similis | an insect - hymenopteran | 1 | 1996 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hepiopelmus variegatorius | an ichneumon wasp | 1 | 2020 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Herpestomus arridens | an ichneumon wasp | 1 | 1996 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Heterarthrus fiora | a sawfly | 1 | 2000 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Heterarthrus nemoratus | a sawfly | 1 | 2014 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Heteropelma | a Heteropelma species (unidentified) | 1 | 2017 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hobbya stenonota | a chalcid wasp | 21 | 2001 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Holcaeus compressus | a chalcid wasp | 1 | 1994 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Homotropus collinus | an ichneumon wasp | 2 | 1998 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Homotropus elegans | an ichneumon wasp | 2 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Homotropus frontorius | an ichneumon wasp | 3 | 2008 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Homotropus nigritarsus | an ichneumon wasp | 3 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Homotropus pallipes | an ichneumon wasp | 1 | 1998 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Homotropus pictus | an ichneumon wasp | 1 | 2002 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hoplitis | a Hoplitis species (unidentified) | 1 | 2016 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hoplitis claviventris | a solitary bee | 3 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hoplocampa crataegi | a sawfly | 1 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hoplocampa testudinea | a sawfly | 2 | 1970 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hybrizon buccatus | an insect - hymenopteran | 1 | 2003 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hylaeus | a Hylaeus species (unidentified) | 5 | 2017 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hylaeus brevicornis | Short Horned Yellow-face Bee | 3 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hylaeus communis | Common Yellow Face Bee | 37 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hylaeus confusus | a solitary bee | 7 | 2023 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hylaeus cornutus | a solitary bee | 8 | 2019 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hylaeus dilatatus ([Genus inferred]) | Chalk Yellow-face Bee | 9 | 2021 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hylaeus hyalinatus | a solitary bee | 9 | 2022 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hylaeus signatus | Large Yellow-faced Bee | 6 | 2006 |
| ant, bee, wasp, sawfly or ichneumon (and others) | Hymenoptera | a Hymenoptera species (unidentified) | 10 | 2023 |
| beetle | Habrocerus capillaricornis | a rove beetle | 19 | 2022 |
| beetle | Hadroplontus litura | a weevil | 2 | 2004 |
| beetle | Haliplidae | a Haliplidae crawling water beetle (unidentified) | 20 | 2011 |
| beetle | Haliplus | a Haliplus crawling water beetle (unidentified) | 21 | 2013 |
| beetle | Haliplus confinis | a crawling water beetle | 11 | 2011 |
| beetle | Haliplus flavicollis | a crawling water beetle | 11 | 2022 |
| beetle | Haliplus fluviatilis | a crawling water beetle | 9 | 2002 |
| beetle | Haliplus fulvus | a crawling water beetle | 6 | 2002 |
| beetle | Haliplus heydeni | a crawling water beetle | 53 | 2006 |
| beetle | Haliplus immaculatus | a crawling water beetle | 58 | 2017 |
| beetle | Haliplus lineatocollis | a crawling water beetle | 237 | 2014 |
| beetle | Haliplus lineolatus | a crawling water beetle | 1 | 2014 |
| beetle | Haliplus mucronatus | a crawling water beetle | 3 | 2000 |
| beetle | Haliplus obliquus | a crawling water beetle | 12 | 2013 |
| beetle | Haliplus ruficollis | a crawling water beetle | 167 | 2013 |
| beetle | Haliplus ruficollis agg. | a crawling water beetle | 225 | 2013 |
| beetle | Haliplus sibiricus | a crawling water beetle | 63 | 2013 |
| beetle | Haliplus sp. or Brychius sp. or Peltodytes sp. (unidentified) | a crawling water beetle (unidentified) | 1 | 2008 |
| beetle | Hallomenus binotatus | a false darkling beetle | 4 | 2020 |
| beetle | Halyzia sedecimguttata | Orange/16-spot Ladybird | 166 | 2023 |
| beetle | Harmonia axyridis | Harlequin Ladybird | 1019 | 2023 |
| beetle | Harmonia quadripunctata | Four-spot Ladybird | 21 | 2022 |
| beetle | Harpalus | a Harpalus species (unidentified) | 3 | 2023 |
| beetle | Harpalus affinis | a ground beetle | 45 | 2023 |
| beetle | Harpalus rubripes | a ground beetle | 4 | 2020 |
| beetle | Harpalus rufipalpis | a ground beetle | 2 | 2000 |
| beetle | Harpalus rufipes | Strawberry Seed Beetle | 120 | 2022 |
| beetle | Harpalus tardus | a ground beetle | 6 | 1999 |
| beetle | Hedobia imperialis | a wood boring beetle | 8 | 2018 |
| beetle | Helochares | a Helochares species (unidentified) | 1 | 1997 |
| beetle | Helochares lividus | a scavenger water beetle | 74 | 2013 |
| beetle | Helochares punctatus | a scavenger water beetle | 1 | 2002 |
| beetle | Helophorus | a Helophorus scavenger water beetle (unidentified) | 74 | 2023 |
| beetle | Helophorus aequalis | a scavenger water beetle | 65 | 2023 |
| beetle | Helophorus brevipalpis | a scavenger water beetle | 310 | 2022 |
| beetle | Helophorus fulgidicollis | a scavenger water beetle | 3 | 2009 |
| beetle | Helophorus grandis | a scavenger water beetle | 124 | 2020 |
| beetle | Helophorus granularis | a scavenger water beetle | 2 | 2011 |
| beetle | Helophorus griseus | a scavenger water beetle | 14 | 2013 |
| beetle | Helophorus laticollis | New Forest Mud Beetle | 2 | 1999 |
| beetle | Helophorus minutus | a scavenger water beetle | 81 | 2013 |
| beetle | Helophorus nanus | a scavenger water beetle | 1 | 2001 |
| beetle | Helophorus nubilus | Wheat Mud Beetle | 1 | 2001 |
| beetle | Helophorus obscurus | a scavenger water beetle | 13 | 2018 |
| beetle | Helophorus strigifrons | a scavenger water beetle | 2 | 1996 |
| beetle | Helophorus tuberculatus | a scavenger water beetle | 1 | 1950 |
| beetle | Hemicrepidius hirtus | a click beetle | 2 | 2013 |
| beetle | Henoticus serratus | a silken fungus beetle | 2 | 2016 |
| beetle | Hermaeophaga mercurialis | Dogs-mercury Flea Beetle | 14 | 2020 |
| beetle | Heterocerus fenestratus | a mud beetle | 12 | 2020 |
| beetle | Heterocerus flexuosus | a mud beetle | 1 | 2018 |
| beetle | Heterothops binotatus | a rove beetle | 1 | 2019 |
| beetle | Heterothops dissimilis | a rove beetle | 2 | 2003 |
| beetle | Heterothops niger | a rove beetle | 1 | 2015 |
| beetle | Hippodamia variegata | Adonis' Ladybird | 16 | 2022 |
| beetle | Hippuriphila modeeri | Horsetail Flea Beetle | 1 | 1984 |
| beetle | Hister unicolor | a carrion beetle | 7 | 2014 |
| beetle | Holotrichapion ononis | a seed weevil | 5 | 2019 |
| beetle | Homalota plana | a rove beetle | 1 | 2001 |
| beetle | Hoplia philanthus | Welsh Chafer | 16 | 2021 |
| beetle | Hydaticus | a Hydaticus species (unidentified) | 2 | 1997 |
| beetle | Hydaticus seminiger | a water beetle | 2 | 2012 |
| beetle | Hydaticus transversalis | a water beetle | 61 | 2023 |
| beetle | Hydraena | a small water beetle (unidentified) | 11 | 2012 |
| beetle | Hydraena britteni | a small water beetle | 1 | 1997 |
| beetle | Hydraena riparia | a small water beetle | 14 | 2013 |
| beetle | Hydraena rufipes | a small water beetle | 1 | 1999 |
| beetle | Hydraena testacea | a small water beetle | 3 | 1999 |
| beetle | Hydrobius fuscipes | a scavenger water beetle | 192 | 2023 |
| beetle | Hydrochus angustatus | a scavenger water beetle | 5 | 2011 |
| beetle | Hydroglyphus geminus | a water beetle | 26 | 2013 |
| beetle | Hydrophilidae | a scavenger water beetle (unidentified) | 63 | 2020 |
| beetle | Hydrophilus piceus | Great Silver Water Beetle | 51 | 2022 |
| beetle | Hydroporinae | a Hydroporinae species (unidentified) | 11 | 2012 |
| beetle | Hydroporus | a Hydroporus water beetle (unidentified) | 3 | 2013 |
| beetle | Hydroporus angustatus | a water beetle | 154 | 2013 |
| beetle | Hydroporus discretus | a water beetle | 2 | 2021 |
| beetle | Hydroporus erythrocephalus | a water beetle | 7 | 2002 |
| beetle | Hydroporus incognitus | a water beetle | 34 | 2013 |
| beetle | Hydroporus memnonius | a water beetle | 9 | 2002 |
| beetle | Hydroporus morio | a water beetle | 1 | 1920 |
| beetle | Hydroporus nigrita | a water beetle | 17 | 2004 |
| beetle | Hydroporus palustris | a water beetle | 228 | 2013 |
| beetle | Hydroporus planus | a water beetle | 151 | 2018 |
| beetle | Hydroporus pubescens | a water beetle | 78 | 2014 |
| beetle | Hydroporus striola | a water beetle | 12 | 1999 |
| beetle | Hydroporus tessellatus | a water beetle | 88 | 2014 |
| beetle | Hydrothassa glabra | a leaf beetle | 5 | 2021 |
| beetle | Hydrothassa marginella | a leaf beetle | 9 | 2021 |
| beetle | Hygrobia hermanni | Screech beetle,Squeak beetle | 29 | 2012 |
| beetle | Hygrotus | a Hygrotus species (unidentified) | 2 | 2012 |
| beetle | Hygrotus confluens | a water beetle | 29 | 2011 |
| beetle | Hygrotus impressopunctatus | a water beetle | 24 | 2016 |
| beetle | Hygrotus inaequalis | a water beetle | 212 | 2014 |
| beetle | Hygrotus nigrolineatus | a water beetle | 1 | 2021 |
| beetle | Hygrotus parallelogrammus | a water beetle | 4 | 1999 |
| beetle | Hygrotus versicolor | a water beetle | 22 | 2012 |
| beetle | Hylastes | a Hylastes species (unidentified) | 2 | 2011 |
| beetle | Hylesinus crenatus | a bark or ambrosia beetle | 9 | 2020 |
| beetle | Hylesinus toranio | a bark or ambrosia beetle | 7 | 2020 |
| beetle | Hylesinus varius | Ash Bark Beetle | 40 | 2023 |
| beetle | Hylobius abietis | Pine Weevil | 4 | 2020 |
| beetle | Hylurgops palliatus | a bark or ambrosia beetle | 2 | 2016 |
| beetle | Hypera arator | a weevil | 1 | 1947 |
| beetle | Hypera meles | a weevil | 8 | 2021 |
| beetle | Hypera nigrirostris | a weevil | 10 | 2018 |
| beetle | Hypera plantaginis | a weevil | 8 | 2010 |
| beetle | Hypera pollux | a weevil | 1 | 2015 |
| beetle | Hypera postica | Clover Leaf Weevil | 10 | 2019 |
| beetle | Hypera rumicis | a weevil | 9 | 2023 |
| beetle | Hypera suspiciosa | a weevil | 14 | 2010 |
| beetle | Hypera zoilus | a weevil | 5 | 2018 |
| beetle | Hyphydrus | a Hyphydrus species (unidentified) | 1 | 2011 |
| beetle | Hyphydrus ovatus | a water beetle | 156 | 2014 |
| beetle | Hypocaccus dimidiatus subsp. maritimus | an insect - beetle (Coleoptera) | 1 | 2017 |
| beetle | Hypopycna rufula | a rove beetle | 1 | 2018 |
| beetle | Hypulus quercinus | a false darkling beetle | 4 | 2016 |
| bird | Haematopus ostralegus | Oystercatcher | 11903 | 2024 |
| bird | Haliaeetus albicilla | White-tailed Eagle | 11 | 2021 |
| bird | Hieraaetus pennatus | Booted Eagle | 4 | 2000 |
| bird | Himantopus himantopus | Black-winged Stilt | 72 | 2022 |
| bird | Hippolais polyglotta | Melodious Warbler | 1 | 1986 |
| bird | Hirundinidae | a swallow or martin (unidentified) | 28 | 2020 |
| bird | Hirundo rustica | Swallow | 19750 | 2023 |
| bird | Hydrobates pelagicus | Storm Petrel | 220 | 2022 |
| bird | Hydrocoloeus minutus | Little Gull | 1000 | 2022 |
| bird | Hydroprogne caspia | Caspian Tern | 2 | 2016 |
| bug | Halticus luteicollis | a plantbug or grassbug | 2 | 2019 |
| bug | Harpocera thoracica | a plantbug or grassbug | 75 | 2023 |
| bug | Hayhurstia atriplicis | an aphid | 2 | 2013 |
| bug | Hebrus (Hebrusella) ruficeps | Sphagnum Bug | 1 | 1937 |
| bug | Hemiptera | A Hemiptera bug (unidentified) | 20 | 2023 |
| bug | Hesperocorixa | a Hesperocorixa species (unidentified) | 20 | 2013 |
| bug | Hesperocorixa linnaei | a waterboatman | 95 | 2014 |
| bug | Hesperocorixa moesta | a waterboatman | 9 | 2011 |
| bug | Hesperocorixa sahlbergi | a waterboatman | 122 | 2022 |
| bug | Heterocordylus (Heterocordylus) genistae | a plantbug or grassbug | 11 | 2021 |
| bug | Heterogaster artemisiae | a ground bug | 3 | 2000 |
| bug | Heterogaster urticae | Nettle Groundbug | 98 | 2023 |
| bug | Heterotoma | a Heterotoma species (unidentified) | 2 | 2015 |
| bug | Heterotoma planicornis | a plantbug or grassbug | 106 | 2023 |
| bug | Himacerus (Anaptus) major | a damsel bug | 12 | 2019 |
| bug | Himacerus (Aptus) mirmicoides | Ant Damsel Bug | 66 | 2023 |
| bug | Himacerus (Himacerus) apterus | Tree Damsel Bug | 30 | 2023 |
| bug | Homoptera | a Homoptera species (unidentified) | 1 | 2010 |
| bug | Hoplomachus thunbergii | a plantbug or grassbug | 3 | 2013 |
| bug | Hyadaphis foeniculi | Honeysuckle Aphid | 2 | 1997 |
| bug | Hyalopterus pruni | Mealy Plum Aphid | 17 | 1975 |
| bug | Hydrometra | a water measurer (unidentified) | 18 | 2006 |
| bug | Hydrometra stagnorum | Water Measurer | 139 | 2023 |
| bug | Hydrometridae | a Hydrometridae species (unidentified) | 3 | 2018 |
| bug | Hyledelphax elegantula | a planthopper | 2 | 2019 |
| bug | Hyperomyzus (Hyperomyzus) lactucae | Currant-Sowthistle Aphid | 14 | 1977 |
| caddis fly | Halesus digitatus | a caddisfly | 1 | 2018 |
| caddis fly | Halesus radiatus | a caddisfly | 6 | 2019 |
| caddis fly | Holocentropus dubius | a caddisfly | 2 | 2011 |
| caddis fly | Holocentropus picicornis | a caddisfly | 5 | 2004 |
| caddis fly | Hydropsyche | a Hydropsyche caddisfly (unidentified) | 16 | 2023 |
| caddis fly | Hydropsyche angustipennis | a caddisfly | 3 | 2018 |
| caddis fly | Hydropsyche fulvipes | a caddisfly | 2 | 2019 |
| caddis fly | Hydropsyche instabilis | a caddisfly | 3 | 2018 |
| caddis fly | Hydropsyche pellucidula | a caddisfly | 6 | 2018 |
| caddis fly | Hydropsyche siltalai | a caddisfly | 12 | 2019 |
| caddis fly | Hydropsychidae | a Hydropsychidae caddisfly (unidentified) | 9 | 2002 |
| caddis fly | Hydroptila | a Hydroptila caddisfly (unidentified) | 1 | 1997 |
| caddis fly | Hydroptila sparsa | a caddisfly | 1 | 2007 |
| caddis fly | Hydroptilidae | a Hydroptilidae caddisfly (unidentified) | 15 | 2003 |
| centipede | Haplophilus | a Haplophilus species (unidentified) | 1 | 2023 |
| centipede | Haplophilus subterraneus | Western Yellow Centipede | 32 | 2023 |
| crustacean | Haustorius arenarius | a crustacean | 1 | 1976 |
| crustacean | Homarus gammarus | Lobster | 6 | 2021 |
| fish | Hippoglossus hippoglossus | Atlantic Halibut | 1 | 1639 |
| fish | Hyperoplus lanceolatus | Greater Sand-eel | 3 | 1941 |
| fungus | Hapalopilus nidulans | a basidiomycete fungus | 5 | 2020 |
| fungus | Hebeloma | a Hebeloma agaric (unidentified) | 6 | 2014 |
| fungus | Hebeloma aestivale | a fungus | 14 | 2014 |
| fungus | Hebeloma ammophilum | a fungus | 1 | 2001 |
| fungus | Hebeloma cavipes | a fungus | 1 | 2010 |
| fungus | Hebeloma crustuliniforme | Poison Pie | 78 | 2014 |
| fungus | Hebeloma fragilipes | a fungus | 10 | 2010 |
| fungus | Hebeloma fusisporum | a fungus | 3 | 2010 |
| fungus | Hebeloma hiemale | an agaric | 7 | 2014 |
| fungus | Hebeloma leucosarx | an agaric | 22 | 2013 |
| fungus | Hebeloma mesophaeum | an agaric | 20 | 2011 |
| fungus | Hebeloma pusillum | an agaric | 4 | 1990 |
| fungus | Hebeloma sacchariolens | Scented Hebeloma | 24 | 2010 |
| fungus | Hebeloma sinapizans | an agaric | 33 | 2014 |
| fungus | Hebeloma sinuosum | an agaric | 3 | 1997 |
| fungus | Hebeloma sordescens | a fungus | 2 | 2010 |
| fungus | Hebeloma theobrominum | a fungus | 7 | 2013 |
| fungus | Helminthosphaeria clavariarum | an ascomycete fungus | 2 | 2020 |
| fungus | Helvella | a Helvella species (unidentified) | 1 | 2008 |
| fungus | Helvella acetabulum | Vinegar Cup | 5 | 2015 |
| fungus | Helvella atra | a fungus | 4 | 2014 |
| fungus | Helvella crispa | White Saddle | 34 | 2023 |
| fungus | Helvella elastica | a fungus | 4 | 2022 |
| fungus | Helvella ephippium | an ascomycete fungus | 2 | 2005 |
| fungus | Helvella lacunosa | a fungus | 20 | 2014 |
| fungus | Helvella latispora | a fungus | 1 | 2009 |
| fungus | Helvella leucomelaena | a fungus | 1 | 2012 |
| fungus | Helvella macropus | a fungus | 5 | 1999 |
| fungus | Hemileucoglossum elongatum | an ascomycete fungus | 3 | 2011 |
| fungus | Hemimycena angustispora | a basidiomycete fungus | 2 | 2007 |
| fungus | Hemimycena candida | a basidiomycete fungus | 1 | 2014 |
| fungus | Hemimycena cephalotricha | a fungus | 2 | 2008 |
| fungus | Hemimycena cucullata | a basidiomycete fungus | 33 | 2014 |
| fungus | Hemimycena delectabilis | a basidiomycete fungus | 3 | 2010 |
| fungus | Hemimycena lactea | a basidiomycete fungus | 20 | 2013 |
| fungus | Hemimycena mairei | a basidiomycete fungus | 5 | 2006 |
| fungus | Hemimycena tortuosa | Dewdrop Bonnet | 19 | 2013 |
| fungus | Henningsomyces candidus | a basidiomycete fungus | 1 | 2007 |
| fungus | Hericium cirrhatum | a basidiomycete fungus | 1 | 2018 |
| fungus | Heterobasidion annosum | Root Fomes | 34 | 2014 |
| fungus | Heterosphaeria patella | an ascomycete fungus | 9 | 2010 |
| fungus | Hohenbuehelia cyphelliformis | a basidiomycete fungus | 2 | 1995 |
| fungus | Hohenbuehelia fluxilis | a basidiomycete fungus | 1 | 2013 |
| fungus | Hohenbuehelia petaloides | a basidiomycete fungus | 3 | 2010 |
| fungus | Humaria hemisphaerica | a fungus | 3 | 2021 |
| fungus | Hyalinia dilutella var. dilutella | an ascomycete fungus | 4 | 2001 |
| fungus | Hyalopeziza millepunctata | an ascomycete fungus | 3 | 1998 |
| fungus | Hyaloscypha daedaleae | a fungus | 1 | 2008 |
| fungus | Hyaloscypha hyalina | an ascomycete fungus | 2 | 2005 |
| fungus | Hyaloscypha leuconica var. leuconica | an ascomycete fungus | 2 | 1997 |
| fungus | Hyaloscypha quercicola | an ascomycete fungus | 1 | 1994 |
| fungus | Hydnellum concrescens | a tooth fungus | 1 | 1999 |
| fungus | Hydnum repandum | Hedgehog Fungus | 14 | 2019 |
| fungus | Hydnum rufescens | a chantarelle | 5 | 2019 |
| fungus | Hydropus floccipes | a basidiomycete fungus | 17 | 2013 |
| fungus | Hydropus subalpinus | a basidiomycete fungus | 2 | 2013 |
| fungus | Hygrocybe | a waxcap (basidiomycete fungus) (unidentified) | 8 | 2023 |
| fungus | Hygrocybe acutoconica | a basidiomycete fungus | 6 | 2011 |
| fungus | Hygrocybe acutoconica var. acutoconica | a basidiomycete fungus | 5 | 2022 |
| fungus | Hygrocybe acutoconica var. konradii | a basidiomycete fungus | 1 | 1997 |
| fungus | Hygrocybe aurantiosplendens | a basidiomycete fungus | 27 | 2020 |
| fungus | Hygrocybe calciphila | a basidiomycete fungus | 2 | 2013 |
| fungus | Hygrocybe calyptriformis var. calyptriformis | a basidiomycete fungus | 5 | 2015 |
| fungus | Hygrocybe cantharellus | a basidiomycete fungus | 10 | 2010 |
| fungus | Hygrocybe ceracea | a basidiomycete fungus | 88 | 2022 |
| fungus | Hygrocybe chlorophana | a basidiomycete fungus | 132 | 2020 |
| fungus | Hygrocybe citrinovirens | a basidiomycete fungus | 7 | 2008 |
| fungus | Hygrocybe coccinea | Scarlet Hood | 90 | 2022 |
| fungus | Hygrocybe colemanniana | a basidiomycete fungus | 17 | 2013 |
| fungus | Hygrocybe conica | Conical Wax-cap | 218 | 2020 |
| fungus | Hygrocybe flavescens | a basidiomycete fungus | 19 | 2008 |
| fungus | Hygrocybe flavipes | a fungus | 20 | 2010 |
| fungus | Hygrocybe fornicata | a basidiomycete fungus | 9 | 2014 |
| fungus | Hygrocybe fornicata var. fornicata | Earthy Waxcap | 1 | 1992 |
| fungus | Hygrocybe glutinipes | a fungus | 8 | 2015 |
| fungus | Hygrocybe glutinipes var. glutinipes | a basidiomycete fungus | 8 | 2008 |
| fungus | Hygrocybe helobia | a basidiomycete fungus | 28 | 2009 |
| fungus | Hygrocybe insipida | a basidiomycete fungus | 97 | 2023 |
| fungus | Hygrocybe intermedia | a basidiomycete fungus | 34 | 2020 |
| fungus | Hygrocybe marchii | a basidiomycete fungus | 12 | 2015 |
| fungus | Hygrocybe miniata | a basidiomycete fungus | 16 | 2019 |
| fungus | Hygrocybe mucronella | a basidiomycete fungus | 13 | 2014 |
| fungus | Hygrocybe nigrescens | Blackening Wax-cap | 5 | 2017 |
| fungus | Hygrocybe nitrata | a basidiomycete fungus | 9 | 2015 |
| fungus | Hygrocybe phaeococcinea | a fungus | 3 | 2010 |
| fungus | Hygrocybe pratensis | Meadow Wax-cap | 69 | 2020 |
| fungus | Hygrocybe pratensis var. pallida | a Hygrocybe fungus | 2 | 2013 |
| fungus | Hygrocybe pratensis var. pratensis | a fungus | 62 | 2017 |
| fungus | Hygrocybe punicea | Crimson Wax-cap | 33 | 2020 |
| fungus | Hygrocybe quieta | a basidiomycete fungus | 46 | 2020 |
| fungus | Hygrocybe reidii | a basidiomycete fungus | 37 | 2014 |
| fungus | Hygrocybe russocoriacea | a basidiomycete fungus | 51 | 2019 |
| fungus | Hygrocybe spadicea | Date-Coloured Waxcap | 3 | 2010 |
| fungus | Hygrocybe splendidissima | a basidiomycete fungus | 3 | 2014 |
| fungus | Hygrocybe virginea | a fungus | 82 | 2020 |
| fungus | Hygrocybe virginea var. fuscescens | a basidiomycete fungus | 2 | 2003 |
| fungus | Hygrocybe virginea var. ochraceopallida | a basidiomycete fungus | 12 | 2014 |
| fungus | Hygrocybe vitellina | a basidiomycete fungus | 1 | 2001 |
| fungus | Hygrophoraceae | a Hygrophoraceae species (unidentified) | 2 | 2023 |
| fungus | Hygrophoropsis aurantiaca | False Chanterelle | 43 | 2014 |
| fungus | Hygrophoropsis fuscosquamula | a bolete | 2 | 1992 |
| fungus | Hygrophorus chrysodon | a basidiomycete fungus | 8 | 2012 |
| fungus | Hygrophorus cossus | a basidiomycete fungus | 3 | 2014 |
| fungus | Hygrophorus dichrous (nom. nud.) | a basidiomycete fungus | 9 | 1998 |
| fungus | Hygrophorus discoxanthus | a basidiomycete fungus | 14 | 2014 |
| fungus | Hygrophorus eburneus | Ivory Wax-cap | 13 | 2014 |
| fungus | Hygrophorus hypothejus | Herald of Winter | 1 | 2014 |
| fungus | Hygrophorus leucophaeus | a basidiomycete fungus | 4 | 2001 |
| fungus | Hygrophorus lindtneri | a basidiomycete fungus | 1 | 2005 |
| fungus | Hygrophorus persoonii | a fungus | 13 | 2010 |
| fungus | Hygrophorus unicolor | a fungus | 12 | 2014 |
| fungus | Hymenochaetaceae | a Hymenochaetaceae species (unidentified) | 2 | 2023 |
| fungus | Hymenochaete corrugata | Glue Fungus | 51 | 2013 |
| fungus | Hymenochaete rubiginosa | a basidiomycete fungus | 90 | 2014 |
| fungus | Hymenogaster griseus | a fungus | 1 | 2008 |
| fungus | Hymenogaster hessei | a fungus | 1 | 1959 |
| fungus | Hymenogaster luteus | a fungus | 2 | 2008 |
| fungus | Hymenogaster olivaceus | a fungus | 4 | 2008 |
| fungus | Hymenogaster tener | a fungus | 1 | 1959 |
| fungus | Hymenogaster vulgaris | a fungus | 1 | 2008 |
| fungus | Hymenoscyphus | a Hymenoscyphus species (unidentified) | 2 | 2002 |
| fungus | Hymenoscyphus calyculus | an ascomycete fungus | 2 | 2000 |
| fungus | Hymenoscyphus fraxineus | Ash Dieback | 5 | 2020 |
| fungus | Hymenoscyphus fructigenus | an ascomycete fungus | 5 | 2000 |
| fungus | Hymenoscyphus laetus | an ascomycete fungus | 1 | 2005 |
| fungus | Hymenoscyphus repandus | an ascomycete fungus | 1 | 1997 |
| fungus | Hymenoscyphus scutula | an ascomycete fungus | 2 | 2008 |
| fungus | Hymenoscyphus vitellinus | an ascomycete fungus | 1 | 2020 |
| fungus | Hymenoscyphus vitigenus | an ascomycete fungus | 2 | 1999 |
| fungus | Hyphoderma setigerum | a basidiomycete fungus | 12 | 2013 |
| fungus | Hyphodontia alutaria | a basidiomycete fungus | 1 | 2012 |
| fungus | Hyphodontia barba-jovis | a basidiomycete fungus | 1 | 2012 |
| fungus | Hyphodontia crustosa | a basidiomycete fungus | 1 | 2013 |
| fungus | Hyphodontia nespori | a fungus | 4 | 2010 |
| fungus | Hyphodontia sambuci | a basidiomycete fungus | 37 | 2017 |
| fungus | Hyphodontia subalutacea | a basidiomycete fungus | 1 | 2010 |
| fungus | Hypholoma capnoides | an agaric | 5 | 2023 |
| fungus | Hypholoma fasciculare | a fungus | 88 | 2023 |
| fungus | Hypholoma fasciculare var. fasciculare | Sulphur Tuft | 228 | 2023 |
| fungus | Hypholoma lateritium | Brick Caps | 6 | 2020 |
| fungus | Hypochnicium bombycinum | a fungus | 1 | 2007 |
| fungus | Hypochnicium geogenium | a basidiomycete fungus | 1 | 2010 |
| fungus | Hypocrea rufa | an ascomycete fungus | 2 | 2014 |
| fungus | Hypocrea schweinitzii | an ascomycete fungus | 1 | 1970 |
| fungus | Hypocreopsis rhododendri | Hazel Gloves | 1 | 2022 |
| fungus | Hypomyces aurantius | an ascomycete fungus | 1 | 1997 |
| fungus | Hypomyces chrysospermus | an ascomycete fungus | 2 | 2012 |
| fungus | Hypomyces rosellus | an ascomycete fungus | 3 | 2013 |
| fungus | Hyponectria buxi | an ascomycete fungus | 1 | 2010 |
| fungus | Hypoxylon fragiforme | Beech Woodwart | 99 | 2014 |
| fungus | Hypoxylon fuscum | Hazel Woodwart | 200 | 2023 |
| fungus | Hypoxylon howeanum | an ascomycete fungus | 7 | 2009 |
| fungus | Hypoxylon intermedium | an ascomycete fungus | 3 | 2010 |
| fungus | Hypoxylon petriniae | a fungus | 4 | 2013 |
| fungus | Hypoxylon rubiginosum | an ascomycete fungus | 92 | 2010 |
| fungus | Hypoxylon subticinense | a fungus | 2 | 2009 |
| fungus | Hysterium angustatum | a fungus | 7 | 2013 |
| fungus | Hysterium pulicare | a fungus | 1 | 2011 |
| fungus | Hysterobrevium mori | a fungus | 1 | 2010 |
| fungus | Hysterostegiella dumeti | an ascomycete fungus | 1 | 1997 |
| leech, flatworm or ribbon worm | Haemopis sanguisuga | Horse Leech | 29 | 2023 |
| leech, flatworm or ribbon worm | Helobdella stagnalis | a leech | 18 | 2013 |
| leech, flatworm or ribbon worm | Hemiclepsis marginata | a leech | 10 | 2013 |
| leech, flatworm or ribbon worm | Hirudinea | a Hirudinea leech (unidentified) | 102 | 2016 |
| leech, flatworm or ribbon worm | Hirudinoidea, Hirudinidae, Haemopidae, Erpobdellidae, Piscicolidae or Glossiphonidae sp. (unidentified leech) | a leech (unidentified) | 11 | 2018 |
| lichen | Haematomma ochroleucum var. ochroleucum | a lichen | 1 | 2008 |
| lichen | Hydropunctaria maura | a lichen | 4 | 2016 |
| lichen | Hymenelia prevostii | a lichen | 6 | 2018 |
| lichen | Hyperphyscia adglutinata | a lichen | 8 | 2023 |
| lichen | Hypogymnia | a Hypogymnia species (unidentified) | 1 | 2014 |
| lichen | Hypogymnia physodes | Heather-rags | 19 | 2011 |
| lichen | Hypogymnia tubulosa | a lichen | 14 | 2016 |
| lichen | Hypotrachyna | a Hypotrachyna species (unidentified) | 1 | 2023 |
| lichen | Hypotrachyna britannica | a lichen | 2 | 1985 |
| lichen | Hypotrachyna laevigata | a lichen | 1 | 2023 |
| lichen | Hypotrachyna revoluta s. lat. | a lichen | 19 | 2023 |
| mammal | Hydrochaeris hydrochaeris | Capybara | 1 | 2020 |
| mammal - marine | Halichoerus grypus | Grey Seal | 47 | 2021 |
| mammal - marine | Hyperoodon ampullatus | Northern bottlenose whale | 2 | 1860 |
| mayfly | Habrophlebia fusca | a mayfly | 2 | 1992 |
| mayfly | Heptagenia sulphurea | a mayfly | 1 | 1991 |
| mayfly | Heptageniidae | a Heptageniidae mayfly (unidentified) | 2 | 1995 |
| mollusc | Helicella itala | Heath Snail | 4 | 2010 |
| mollusc | Helicidae | a Helicidae species (unidentified) | 2 | 2023 |
| mollusc | Helicigona lapicida | Lapidary Snail | 44 | 2018 |
| mollusc | Helicoidea | a helicoidea snail | 19 | 2023 |
| mollusc | Helix | a Helix species (unidentified) | 1 | 2015 |
| mollusc | Helix (Helix) pomatia | Roman Snail | 2 | 2016 |
| mollusc | Hippeutis complanatus | Flat Ramshorn | 75 | 2013 |
| mollusc | Hydrobia | a Hydrobia species (unidentified) | 1 | 2012 |
| mollusc | Hydrobiidae | a spire snail (unidentified) | 24 | 2003 |
| mollusc | Hygromia (Hygromia) cinctella | Girdled Snail | 62 | 2023 |
| mollusc | Hygromia (Riedelia) limbata | a snail | 1 | 2005 |
| mollusc | Hygromiidae | a Hygromiidae species (unidentified) | 3 | 2023 |
| moss | Heterocladium dimorphum | Dimorphous Tamarisk-moss | 1 | 1995 |
| moss | Homalia trichomanoides | Blunt Feather-moss | 17 | 2022 |
| moss | Homalothecium | a Homalothecium species (unidentified) | 1 | 2023 |
| moss | Homalothecium lutescens | Yellow Feather-moss | 56 | 2023 |
| moss | Homalothecium sericeum | Silky Wall Feather-moss | 178 | 2023 |
| moss | Hygroamblystegium tenax | Fountain Feather-moss | 5 | 2022 |
| moss | Hygrohypnum luridum | Drab Brook-moss | 1 | 2016 |
| moss | Hylocomium | a Hylocomium species (unidentified) | 1 | 1941 |
| moss | Hylocomium splendens | Glittering Wood-moss | 16 | 2022 |
| moss | Hymenostylium recurvirostrum | Hook-beak Tufa-moss | 3 | 2020 |
| moss | Hypnales | a Hypnales species (unidentified) | 2 | 2023 |
| moss | Hypnum | a Hypnum species (unidentified) | 8 | 2019 |
| moss | Hypnum andoi | Mamillate Plait-moss | 38 | 2021 |
| moss | Hypnum cupressiforme | Cypress-leaved Plait-moss | 124 | 2023 |
| moss | Hypnum cupressiforme (sensu lato) | a moss | 19 | 2013 |
| moss | Hypnum cupressiforme var. cupressiforme | a Cypress-leaved Plait-moss | 22 | 2023 |
| moss | Hypnum cupressiforme var. lacunosum | Great Plait-moss | 32 | 2023 |
| moss | Hypnum cupressiforme var. resupinatum | Supine Plait-moss | 83 | 2023 |
| moss | Hypnum jutlandicum | Heath Plait-moss | 12 | 2023 |
| moth or butterfly - butterfly | Hamearis lucina | Duke of Burgundy Fritillary | 13 | 1998 |
| moth or butterfly - butterfly | Hesperiidae | a skipper (unidentified) | 22 | 2019 |
| moth or butterfly - butterfly | Hipparchia semele | Grayling | 300 | 2019 |
| moth or butterfly - macro moth | Habrosyne pyritoides | Buff Arches | 1488 | 2023 |
| moth or butterfly - macro moth | Hada plebeja | Shears | 136 | 2021 |
| moth or butterfly - macro moth | Hadena bicruris | Lychnis (moth) | 689 | 2023 |
| moth or butterfly - macro moth | Hadena compta | Varied Coronet | 32 | 2020 |
| moth or butterfly - macro moth | Hadena confusa | Marbled Coronet | 8 | 2020 |
| moth or butterfly - macro moth | Hadena perplexa perplexa | Tawny Shears | 12 | 2016 |
| moth or butterfly - macro moth | Hecatera bicolorata | Broad-barred White | 144 | 2023 |
| moth or butterfly - macro moth | Hecatera dysodea | Small Ranunculus | 143 | 2023 |
| moth or butterfly - macro moth | Helicoverpa armigera | Scarce Bordered Straw | 68 | 2023 |
| moth or butterfly - macro moth | Heliothis peltigera | Bordered Straw | 81 | 2022 |
| moth or butterfly - macro moth | Helotropha leucostigma leucostigma | Crescent | 14 | 2019 |
| moth or butterfly - macro moth | Hemaris fuciformis | Broad-bordered Bee Hawk | 2 | 1994 |
| moth or butterfly - macro moth | Hemaris tityus | Narrow-bordered Bee Hawk-moth | 14 | 2012 |
| moth or butterfly - macro moth | Hemistola chrysoprasaria | Small Emerald | 501 | 2023 |
| moth or butterfly - macro moth | Hemithea aestivaria | Common Emerald | 1091 | 2023 |
| moth or butterfly - macro moth | Hepialus humuli | Ghost Moth | 227 | 2023 |
| moth or butterfly - macro moth | Hepialus humuli humuli | Ghost Moth (ssp. humuli) | 187 | 2021 |
| moth or butterfly - macro moth | Herminia grisealis | Small Fan-foot | 507 | 2023 |
| moth or butterfly - macro moth | Herminia tarsicrinalis | Shaded Fan-foot | 1 | 2004 |
| moth or butterfly - macro moth | Herminia tarsipennalis | Fan-foot | 797 | 2023 |
| moth or butterfly - macro moth | Hippotion celerio | Silver-striped Hawk-moth | 1 | 2011 |
| moth or butterfly - macro moth | Hoplodrina | a Hoplodrina species (unidentified) | 857 | 2022 |
| moth or butterfly - macro moth | Hoplodrina ambigua | Vine's Rustic | 3023 | 2023 |
| moth or butterfly - macro moth | Hoplodrina blanda | Rustic | 1448 | 2023 |
| moth or butterfly - macro moth | Hoplodrina octogenaria | Uncertain | 2216 | 2023 |
| moth or butterfly - macro moth | Hoplodrina octogenaria/blanda | Uncertain/Rustic | 1372 | 2023 |
| moth or butterfly - macro moth | Horisme tersata | Fern Moth (The) | 308 | 2023 |
| moth or butterfly - macro moth | Horisme vitalbata | Small Waved Umber | 323 | 2023 |
| moth or butterfly - macro moth | Hydraecia micacea | Rosy Rustic | 725 | 2023 |
| moth or butterfly - macro moth | Hydrelia flammeolaria | Small Yellow Wave | 312 | 2022 |
| moth or butterfly - macro moth | Hydrelia sylvata | Waved Carpet | 2 | 2001 |
| moth or butterfly - macro moth | Hydria cervinalis | Scarce Tissue | 3 | 1981 |
| moth or butterfly - macro moth | Hydria undulata | Scallop Shell | 34 | 2018 |
| moth or butterfly - macro moth | Hydriomena furcata | July Highflyer | 650 | 2022 |
| moth or butterfly - macro moth | Hydriomena impluviata | May Highflyer | 108 | 2022 |
| moth or butterfly - macro moth | Hydriomena ruberata | Ruddy Highflyer | 2 | 1965 |
| moth or butterfly - macro moth | Hylaea fasciaria | Barred Red | 75 | 2021 |
| moth or butterfly - macro moth | Hyles euphorbiae | Spurge Hawk-moth | 1 | 1898 |
| moth or butterfly - macro moth | Hyles gallii | Bedstraw Hawk-moth | 7 | 2013 |
| moth or butterfly - macro moth | Hyles livornica | Striped Hawk-moth | 14 | 2006 |
| moth or butterfly - macro moth | Hypena crassalis | Beautiful Snout | 10 | 2020 |
| moth or butterfly - macro moth | Hypena obesalis | Paignton Snout | 3 | 2002 |
| moth or butterfly - macro moth | Hypena proboscidalis | Snout | 2943 | 2023 |
| moth or butterfly - macro moth | Hypena rostralis | Buttoned Snout | 33 | 2022 |
| moth or butterfly - macro moth | Hypenodes humidalis | Marsh Oblique-barred | 1 | 1959 |
| moth or butterfly - macro moth | Hypomecis punctinalis | Pale Oak Beauty | 6 | 2009 |
| moth or butterfly - macro moth | Hypomecis roboraria | Great Oak Beauty | 3 | 2019 |
| moth or butterfly - micro moth | Haplotinea insectella | a micro-moth | 1 | 2003 |
| moth or butterfly - micro moth | Hedya nubiferana | Marbled Orchard Tortrix | 314 | 2023 |
| moth or butterfly - micro moth | Hedya ochroleucana | a tortrix moth | 28 | 2022 |
| moth or butterfly - micro moth | Hedya pruniana | Plum Tortrix | 322 | 2022 |
| moth or butterfly - micro moth | Hedya salicella | a tortrix moth | 50 | 2022 |
| moth or butterfly - micro moth | Helcystogramma rufescens | a micro-moth | 102 | 2022 |
| moth or butterfly - micro moth | Heliozela hammoniella | a micro-moth | 1 | 1972 |
| moth or butterfly - micro moth | Heliozela resplendella | a micro-moth | 5 | 2020 |
| moth or butterfly - micro moth | Heliozela sericiella | a micro-moth | 19 | 2019 |
| moth or butterfly - micro moth | Hellinsia carphodactyla | a plume moth | 13 | 2004 |
| moth or butterfly - micro moth | Hellinsia lienigianus | a plume moth | 1 | 2020 |
| moth or butterfly - micro moth | Hellinsia osteodactylus | a plume moth | 6 | 2016 |
| moth or butterfly - micro moth | Hellinsia tephradactyla | a plume moth | 3 | 1964 |
| moth or butterfly - micro moth | Hellula undalis | Old World Webworm | 1 | 1995 |
| moth or butterfly - micro moth | Hofmannophila pseudospretella | Brown House Moth | 1986 | 2023 |
| moth or butterfly - micro moth | Homoeosoma | a Homoeosoma species (unidentified) | 2 | 1906 |
| moth or butterfly - micro moth | Homoeosoma nebulella | a pyralid moth | 10 | 2021 |
| moth or butterfly - micro moth | Homoeosoma sinuella | a pyralid moth | 87 | 2023 |
| moth or butterfly - micro moth | Hypatima rhomboidella | a micro-moth | 38 | 2022 |
| moth or butterfly - micro moth | Hypochalcia ahenella | a pyralid moth | 4 | 2021 |
| moth or butterfly - micro moth | Hypsopygia costalis | Gold Triangle | 848 | 2022 |
| moth or butterfly - micro moth | Hypsopygia glaucinalis | Double-striped Tabby | 249 | 2023 |
| moth or butterfly - micro moth | Hysterophora maculosana | a micro-moth | 11 | 2023 |
| moth or butterfly - moth (macro or micro not listed) moth | Hepialidae | a Hepialidae species (unidentified) | 1 | 2016 |
| plant | Hebe | a Hebe species (unidentified) | 20 | 2017 |
| plant | Hedera | a Hedera species (unidentified) | 21 | 2023 |
| plant | Hedera helix | Ivy | 11374 | 2023 |
| plant | Hedera helix subsp. helix | Common Ivy | 106 | 2015 |
| plant | Hedera hibernica | Atlantic Ivy | 117 | 2023 |
| plant | Hedypnois cretica | Scaly Hawkbit | 1 | 1939 |
| plant | Helianthemum | a rock-rose (uinidentified) | 36 | 2019 |
| plant | Helianthemum apenninum | White Rock-rose | 32 | 2019 |
| plant | Helianthemum nummularium | Common Rock-rose | 746 | 2022 |
| plant | Helianthemum nummularium x apenninum = H. x sulphureum | a rock-rose | 20 | 2019 |
| plant | Helianthus annuus | Sunflower | 44 | 2020 |
| plant | Helianthus petiolaris | Lesser Sunflower | 1 | 1956 |
| plant | Helianthus rigidus x tuberosus | Perennial Sunflower | 6 | 2004 |
| plant | Helianthus tuberosus x pauciflorus = H. x laetiflorus | a flowering plant | 1 | 1931 |
| plant | Helictotrichon | a Helictotrichon species (unidentified) | 2 | 2019 |
| plant | Helictotrichon pratense | Meadow Oat-grass | 344 | 2020 |
| plant | Helictotrichon pubescens | Downy Oat-grass | 437 | 2019 |
| plant | Heliotropium europaeum | a flowering plant | 1 | 1940 |
| plant | Helleborus | a Helleborus species (unidentified) | 12 | 2023 |
| plant | Helleborus argutifolius | Corsican Hellebore | 8 | 2011 |
| plant | Helleborus foetidus | Stinking Hellebore | 113 | 2020 |
| plant | Helleborus orientalis | Lenten-rose | 7 | 2020 |
| plant | Helleborus viridis | a flowering plant | 27 | 2011 |
| plant | Helleborus viridis subsp. occidentalis | Green Hellebore | 48 | 2022 |
| plant | Hemerocallis | a Hemerocallis day-lily (unidentified) | 1 | 2013 |
| plant | Hemerocallis fulva | Orange Day-lily | 26 | 2017 |
| plant | Hemizonia fitchii | a flowering plant | 1 | 1934 |
| plant | Hemizonia kelloggii | a flowering plant | 2 | 1930 |
| plant | Hemizonia pungens | Spikeweed | 3 | 1934 |
| plant | Heracleum mantegazzianum | Giant Hogweed | 85 | 2023 |
| plant | Heracleum sphondylium | Hogweed | 4014 | 2023 |
| plant | Heracleum sphondylium sphondylium angustifolium | a flowering plant | 1 | 1989 |
| plant | Heracleum sphondylium subsp. flavescens | a hogweed | 1 | 2002 |
| plant | Heracleum sphondylium subsp. sphondylium | a hogweed | 3161 | 2003 |
| plant | Herminium monorchis | Musk Orchid | 2 | 1984 |
| plant | Herniaria glabra | Smooth Rupture-wort | 19 | 2010 |
| plant | Herniaria hirsuta | Hairy Rupturewort | 1 | 1937 |
| plant | Hesperis matronalis | Dame's Violet | 99 | 2023 |
| plant | Hibiscus syriacus | a flowering plant | 1 | 2019 |
| plant | Hieracium | a hawkweed (unidentified) | 283 | 2023 |
| plant | Hieracium acuminatum | a hawkweed | 11 | 2007 |
| plant | Hieracium argillaceum | Southern Hawkweed | 2 | 2023 |
| plant | Hieracium diaphanum | a hawkweed | 3 | 1992 |
| plant | Hieracium maculatum | a hawkweed | 227 | 2023 |
| plant | Hieracium maculosum | a hawkweed | 1 | 2001 |
| plant | Hieracium murorum agg. | Few-leaved Hawkweed | 4 | 2005 |
| plant | Hieracium piligerum | a hawkweed | 1 | 1998 |
| plant | Hieracium pulmonarioides | a hawkweed | 1 | 1933 |
| plant | Hieracium rigens | a hawkweed | 1 | 1996 |
| plant | Hieracium sabaudum | Autumn Hawkweed | 15 | 2012 |
| plant | Hieracium salticola | a hawkweed | 5 | 1992 |
| plant | Hieracium scotostictum | a hawkweed | 1 | 2020 |
| plant | Hieracium sect. Sabauda | a hawkweed | 3 | 2006 |
| plant | Hieracium sect. Vulgata | a hawkweed | 2 | 2001 |
| plant | Hieracium speluncarum | a hawkweed | 6 | 2012 |
| plant | Hieracium trichocaulon | a hawkweed | 5 | 2010 |
| plant | Hieracium umbellatum | a hawkweed | 9 | 1999 |
| plant | Hieracium umbellatum subsp. umbellatum | a hawkweed | 1 | 1992 |
| plant | Hieracium vagum | a hawkweed | 7 | 2014 |
| plant | Hieracium vulgatum (auct. Angl.) | a hawkweed | 10 | 2014 |
| plant | Himantoglossum hircinum | Lizard Orchid | 24 | 2012 |
| plant | Hippocrepis comosa | Horseshoe Vetch | 125 | 2021 |
| plant | Hippophae rhamnoides | Sea-buckthorn | 84 | 2023 |
| plant | Hippuris vulgaris | Mare's-tail | 82 | 2020 |
| plant | Hirschfeldia | a Hirschfeldia species (unidentified) | 1 | 2014 |
| plant | Hirschfeldia incana | Hoary Mustard | 120 | 2023 |
| plant | Holcus | a soft-grass (unidentified) | 4 | 1997 |
| plant | Holcus lanatus | Yorkshire-fog | 6641 | 2023 |
| plant | Holcus lanatus x mollis = H. x hybridus | a soft-grass | 1 | 2005 |
| plant | Holcus mollis | Creeping Soft-grass | 245 | 2019 |
| plant | Honckenya peploides | Sea Sandwort | 12 | 2009 |
| plant | Hordeum | a Hordeum species (unidentified) | 5 | 2023 |
| plant | Hordeum cordobense | a flowering plant | 1 | 1930 |
| plant | Hordeum distichon | Two-rowed Barley | 16 | 2016 |
| plant | Hordeum distichon (sensu lato) | a Two-rowed Barley (sensu lato) | 43 | 2007 |
| plant | Hordeum geniculatum | Mediterranean Barley | 3 | 1953 |
| plant | Hordeum jubatum | Foxtail Barley | 3 | 2010 |
| plant | Hordeum marinum | Sea Barley | 67 | 2014 |
| plant | Hordeum murinum | Wall Barley | 549 | 2022 |
| plant | Hordeum murinum subsp. murinum | a wall barley | 788 | 1999 |
| plant | Hordeum secalinum | Meadow Barley | 1321 | 2021 |
| plant | Hordeum vulgare | Six-rowed Barley | 15 | 2020 |
| plant | Hornungia petraea | Hutchinsia | 68 | 2012 |
| plant | Hottonia palustris | Water-violet | 109 | 2013 |
| plant | Houttuynia cordata | Heart-leaved Houttuynia | 1 | 2015 |
| plant | Humulus | a Humulus species (unidentified) | 1 | 2016 |
| plant | Humulus lupulus | Hop | 875 | 2021 |
| plant | Humulus lupulus aureus | Golden Hop | 2 | 2015 |
| plant | Hunnemania fumariifolia | Mexican Tulip Poppy | 2 | 1986 |
| plant | Hyacinthoides | a bluebell (unidentified) | 62 | 2023 |
| plant | Hyacinthoides hispanica | Spanish Bluebell | 396 | 2023 |
| plant | Hyacinthoides italica | Italian Bluebell | 1 | 1986 |
| plant | Hyacinthoides non-scripta | Bluebell | 3894 | 2024 |
| plant | Hyacinthoides non-scripta x hispanica = H. x massartiana | Hybrid Bluebell | 315 | 2023 |
| plant | Hyacinthus orientalis | Hyacinth | 9 | 2022 |
| plant | Hydrangea | a Hydrangea species (unidentified) | 6 | 2015 |
| plant | Hydrangea macrophylla | a Hydrangea | 4 | 2019 |
| plant | Hydrangea petiolaris | a Hydrangea | 2 | 2014 |
| plant | Hydrocharis | a Hydrocharis species (unidentified) | 13 | 2000 |
| plant | Hydrocharis morsus-ranae | Frogbit | 653 | 2018 |
| plant | Hydrocotyle ranunculoides | Floating Pennywort | 19 | 2015 |
| plant | Hydrocotyle vulgaris | Marsh Pennywort | 56 | 2018 |
| plant | Hyoscyamus albus | a flowering plant | 1 | 1937 |
| plant | Hyoscyamus niger | Henbane | 74 | 2023 |
| plant | Hypericum | a St. John's-wort (unidentified) | 95 | 2023 |
| plant | Hypericum androsaemum | Tutsan | 277 | 2023 |
| plant | Hypericum androsaemum x hircinum = H. x inodorum | Tall Tutsan | 21 | 2020 |
| plant | Hypericum calycinum | Rose-of-Sharon | 105 | 2019 |
| plant | Hypericum elodes | Marsh St. John's-wort | 5 | 2009 |
| plant | Hypericum forrestii | a St. John's-wort | 1 | 2013 |
| plant | Hypericum 'Hidcote' | a St. John's-wort | 3 | 2009 |
| plant | Hypericum hircinum | Stinking Tutsan | 6 | 2020 |
| plant | Hypericum hirsutum | Hairy St. John's-wort | 1036 | 2023 |
| plant | Hypericum humifusum | Trailing St. John's-wort | 69 | 2024 |
| plant | Hypericum maculatum | Imperforate St. John's-wort | 46 | 2021 |
| plant | Hypericum maculatum subsp. obtusiusculum | an imperforate St. John's-wort | 18 | 2015 |
| plant | Hypericum montanum | Pale St. John's-wort | 102 | 2019 |
| plant | Hypericum olympicum | a flowering plant | 1 | 2019 |
| plant | Hypericum perforatum | Perforate St. John's-wort | 1899 | 2023 |
| plant | Hypericum perforatum x maculatum = H. x desetangsii | Des Etangs' St. John's-wort | 4 | 2019 |
| plant | Hypericum pulchrum | Slender St. John's-wort | 195 | 2019 |
| plant | Hypericum tetrapterum | Square-stalked St. John's-wort | 1060 | 2023 |
| plant | Hypericum x desetangsii nothossp. carinthiacum | a St. John's-wort | 1 | 1997 |
| plant | Hypochaeris | a cat's-ear (unidentified) | 8 | 2018 |
| plant | Hypochaeris glabra | Smooth Cat's-ear | 7 | 2010 |
| plant | Hypochaeris maculata | Spotted Cat's-ear | 2 | 1997 |
| plant | Hypochaeris radicata | Cat's-ear | 3474 | 2023 |
| plant | Hypopitys monotropa | Yellow Bird's-nest | 21 | 2015 |
| plant | Hypopitys monotropa subsp. hypophegea | a yellow bird's-nest | 1 | 1986 |
| plant | Hypopitys monotropa subsp. monotropa | a yellow bird's-nest | 2 | 1991 |
| sea-fan, sea anemone or jellyfish | Hartlaubella gelatinosa | a Sea-fan/Sea Anemone/Jellyfish | 4 | 2003 |
| sea-fan, sea anemone or jellyfish | Hydrallmania falcata | a Sea-fan/Sea Anemone/Jellyfish | 1 | 1936 |
| sea-fan, sea anemone or jellyfish | Hydra viridissima | Green Hydra | 3 | 2020 |
| slime mould | Hemitrichia abietina | a slime mould | 1 | 2018 |
| slime mould | Hemitrichia calyculata | a slime mould | 7 | 2008 |
| slime mould | Hemitrichia clavata | a slime mould | 3 | 2018 |
| slime mould | Hemitrichia pardina | a slime mould | 1 | 2008 |
| spider | Hahnia montana | a lesser cobweb spider | 3 | 1985 |
| spider | Harpactea hombergi | a woodlouse spider | 23 | 2024 |
| spider | Heliophanus | a Heliophanus species (unidentified) | 6 | 2023 |
| spider | Heliophanus cupreus | a jumping spider | 32 | 2023 |
| spider | Heliophanus flavipes | a jumping spider | 24 | 2020 |
| spider | Hybocoptus corrugis | a money spider | 1 | 1999 |
| spider | Hygrolycosa rubrofasciata | a wolf spider | 1 | 1984 |
| spider | Hypomma bituberculatum | a money spider | 2 | 1999 |
| spider | Hypomma cornutum | a money spider | 2 | 2008 |
| spider | Hypsosinga albovittata | an orb-weaver spider | 12 | 1999 |
| spider | Hypsosinga pygmaea | an orb-weaver spider | 12 | 2001 |
| spider | Hypsosinga sanguinea | an orb-weaver spider | 1 | 1999 |
| spider | Hyptiotes paradoxus | Triangle Spider | 2 | 2000 |
| springtail | Hypogastrura sahlbergi | a springtail (Collembola) | 2 | 1923 |
| stylops | Halictoxenos tumulorum | a stylop | 1 | 2004 |
| tick or mite (acarine) | Hydracarina | a Hydracarina water mite (unidentified) | 80 | 2018 |
| tick or mite (acarine) | Hydrachna | a Hydrachna species (unidentified) | 1 | 1991 |
| trematode | Hemipera | a Hemipera species (unidentified) | 1 | 2014 |
| true fly - | Haematopota | a Haematopota species (unidentified) | 4 | 2017 |
| true fly - | Hebecnema fumosa | a muscid fly | 1 | 1948 |
| true fly - | Hebecnema nigra | a muscid fly | 7 | 2021 |
| true fly - | Hebecnema nigricolor | a muscid fly | 4 | 2001 |
| true fly - | Hebecnema umbratica | a muscid fly | 8 | 2013 |
| true fly - | Hebecnema vespertina | a muscid fly | 7 | 2008 |
| true fly - | Helina | a Helina species (unidentified) | 3 | 2019 |
| true fly - | Helina concolor | a muscid fly | 1 | 1948 |
| true fly - | Helina depuncta | a muscid fly | 5 | 2020 |
| true fly - | Helina evecta | a muscid fly | 13 | 2021 |
| true fly - | Helina impuncta | a muscid fly | 11 | 2020 |
| true fly - | Helina lasiophthalma | a muscid fly | 1 | 2001 |
| true fly - | Helina latitarsis | a muscid fly | 2 | 2008 |
| true fly - | Helina maculipennis | a muscid fly | 1 | 2020 |
| true fly - | Helina obscurata | a muscid fly | 5 | 2004 |
| true fly - | Helina pertusa | a muscid fly | 9 | 1999 |
| true fly - | Helina quadrum | a muscid fly | 1 | 1978 |
| true fly - | Helina reversio | a muscid fly | 6 | 2021 |
| true fly - | Helina subvittata | a muscid fly | 2 | 2020 |
| true fly - | Helina vicina | a muscid fly | 1 | 1949 |
| true fly - | Helius | a Helius species (unidentified) | 1 | 1983 |
| true fly - | Herina | a Herina species (unidentified) | 1 | 2011 |
| true fly - | Herina frondescentiae | a fly | 23 | 2022 |
| true fly - | Herina nigrina | a fly | 12 | 2013 |
| true fly - | Herina palustris | a fly | 1 | 2000 |
| true fly - | Heringia | a Heringia species (unidentified) | 3 | 2018 |
| true fly - | Heteromyza | a Heteromyza species (unidentified) | 7 | 2021 |
| true fly - | Heteromyza rotundicornis | a fly | 6 | 2009 |
| true fly - | Hilara | a Hilara species (unidentified) | 3 | 2023 |
| true fly - | Hirtodrosophila cameraria | a fruit fly | 5 | 2001 |
| true fly - | Homoneura interstincta | a fly | 2 | 2004 |
| true fly - | Homoneura thalhammeri | a fly | 3 | 2021 |
| true fly - | Hyadina guttata | a shore fly | 10 | 2009 |
| true fly - | Hydrellia | a Hydrellia species (unidentified) | 12 | 2018 |
| true fly - | Hydrellia albilabris | a shore fly | 10 | 1999 |
| true fly - | Hydrellia griseola | a shore fly | 13 | 2008 |
| true fly - | Hydrellia maura | a shore fly | 34 | 2022 |
| true fly - | Hydrellia mutata | a shore fly | 1 | 2001 |
| true fly - | Hydrellia obscura | a shore fly | 2 | 2002 |
| true fly - | Hydrellia subalbiceps | a shore fly | 1 | 1983 |
| true fly - | Hydrellia thoracica | a shore fly | 1 | 1999 |
| true fly - | Hydromya dorsalis | a snail-killing fly | 6 | 2002 |
| true fly - | Hydrophoria | a Hydrophoria species (unidentified) | 2 | 2023 |
| true fly - | Hydrophoria lancifer | Deer warble fly | 3 | 2016 |
| true fly - | Hydrophoria linogrisea | a fly | 1 | 2017 |
| true fly - | Hydrophoria ruralis | a fly | 2 | 2008 |
| true fly - | Hydrotaea | a Hydrotaea species (unidentified) | 1 | 2022 |
| true fly - | Hydrotaea albipuncta | a muscid fly | 2 | 2000 |
| true fly - | Hydrotaea armipes | a muscid fly | 1 | 2000 |
| true fly - | Hydrotaea cyrtoneurina | a muscid fly | 3 | 2006 |
| true fly - | Hydrotaea dentipes | a muscid fly | 6 | 2002 |
| true fly - | Hydrotaea diabolus | a muscid fly | 3 | 2008 |
| true fly - | Hydrotaea ignava | a muscid fly | 1 | 2002 |
| true fly - | Hydrotaea militaris | a muscid fly | 3 | 2006 |
| true fly - | Hydrotaea parva | a muscid fly | 2 | 2006 |
| true fly - | Hylemya nigrimana | a fly | 3 | 2020 |
| true fly - | Hylemya urbica | a fly | 1 | 2002 |
| true fly - | Hylemya vagans | a fly | 21 | 2021 |
| true fly - | Hylemya variata | a fly | 2 | 2006 |
| true fly - | Hylemyza partita | a fly | 3 | 2001 |
| true fly - cranefly | Helius flavus | a cranefly | 3 | 2002 |
| true fly - cranefly | Helius longirostris | a cranefly | 3 | 2022 |
| true fly - cranefly | Helius pallirostris | a cranefly | 3 | 2009 |
| true fly - (diptera) | Herina lugubris | an insect - true fly (Diptera) | 23 | 2018 |
| true fly - (diptera) | Heterostylodes pilifer | an insect - true fly (Diptera) | 3 | 2004 |
| true fly - (diptera) | Homoneura notata | an insect - true fly (Diptera) | 6 | 2021 |
| true fly - (diptera) | Homoneura tesquae | an insect - true fly (Diptera) | 3 | 2000 |
| true fly - (diptera) | Hydrellia concolor | an insect - true fly (Diptera) | 1 | 2004 |
| true fly - horse fly | Haematopota bigoti | Big-spotted Cleg | 7 | 1987 |
| true fly - horse fly | Haematopota crassicornis | Black-horned Cleg | 13 | 2018 |
| true fly - horse fly | Haematopota grandis | Long-horned Cleg | 4 | 2000 |
| true fly - horse fly | Haematopota pluvialis | Notch-horned Cleg | 158 | 2022 |
| true fly - horse fly | Hybomitra bimaculata | a horse fly | 9 | 2000 |
| true fly - horse fly | Hybomitra distinguenda | a horse fly | 2 | 1979 |
| true fly - horse fly | Hybomitra montana | a horse fly | 1 | 1979 |
| true fly - hoverfly | Helophilus | a Helophilis hoverfly (unidentified) | 2 | 2016 |
| true fly - hoverfly | Helophilus hybridus | a hoverfly | 33 | 2021 |
| true fly - hoverfly | Helophilus pendulus | a hoverfly | 561 | 2023 |
| true fly - hoverfly | Helophilus trivittatus | a hoverfly | 56 | 2022 |
| true fly - hoverfly | Heringia heringi | a hoverfly | 4 | 2012 |
| true fly - midge, gnat or mosquito | Halocladius varians | a non-biting midge | 3 | 1996 |
| true fly - midge, gnat or mosquito | Harmandiola tremulae | a gall midge | 1 | 2019 |
| true fly - midge, gnat or mosquito | Hartigiola annulipes | a gall midge | 4 | 2019 |
| true fly - robber, empid or dolichopid fly | Heleodromia immaculata | a dance fly | 1 | 2000 |
| true fly - robber, empid or dolichopid fly | Hemerodromia unilineata | a dance fly | 1 | 2006 |
| true fly - robber, empid or dolichopid fly | Hercostomus chetifer | a dolichopodid fly | 1 | 1983 |
| true fly - robber, empid or dolichopid fly | Hercostomus gracilis | a dolichopodid fly | 5 | 2003 |
| true fly - robber, empid or dolichopid fly | Hercostomus nanus | a dolichopodid fly | 5 | 2009 |
| true fly - robber, empid or dolichopid fly | Hercostomus nigrilamellatus | a dolichopodid fly | 1 | 2020 |
| true fly - robber, empid or dolichopid fly | Hercostomus nigripennis | a dolichopodid fly | 3 | 1999 |
| true fly - robber, empid or dolichopid fly | Hercostomus parvilamellatus | a dolichopodid fly | 1 | 2000 |
| true fly - robber, empid or dolichopid fly | Hercostomus plagiatus | a dolichopodid fly | 6 | 2001 |
| true fly - robber, empid or dolichopid fly | Hilara albitarsis | a dance fly | 1 | 1985 |
| true fly - robber, empid or dolichopid fly | Hilara chorica | a dance fly | 4 | 2000 |
| true fly - robber, empid or dolichopid fly | Hilara cornicula | a dance fly | 5 | 2009 |
| true fly - robber, empid or dolichopid fly | Hilara fuscipes | a dance fly | 3 | 2006 |
| true fly - robber, empid or dolichopid fly | Hilara galactoptera | a dance fly | 1 | 2006 |
| true fly - robber, empid or dolichopid fly | Hilara interstincta | a dance fly | 2 | 1983 |
| true fly - robber, empid or dolichopid fly | Hilara litorea | a dance fly | 5 | 2020 |
| true fly - robber, empid or dolichopid fly | Hilara longifurca | a dance fly | 3 | 2002 |
| true fly - robber, empid or dolichopid fly | Hilara lurida | a dance fly | 1 | 1985 |
| true fly - robber, empid or dolichopid fly | Hilara maura | a dance fly | 3 | 2022 |
| true fly - robber, empid or dolichopid fly | Hilara morata | a dance fly | 3 | 2006 |
| true fly - robber, empid or dolichopid fly | Hilara pseudocornicula | a dance fly | 3 | 2013 |
| true fly - robber, empid or dolichopid fly | Hilara rejecta | a dance fly | 1 | 1983 |
| true fly - robber, empid or dolichopid fly | Hilara scrobiculata | a dance fly | 1 | 1980 |
| true fly - robber, empid or dolichopid fly | Hilara thoracica | a dance fly | 4 | 2003 |
| true fly - robber, empid or dolichopid fly | Hybos culiciformis | a dance fly | 6 | 2009 |
| true fly - robber, empid or dolichopid fly | Hybos femoratus | a dance fly | 7 | 2022 |
| woodlouse | Haplophthalmus | a Haplophthalmus woodlouse (unidentified) | 1 | 2006 |
| woodlouse | Haplophthalmus danicus | a woodlouse | 7 | 2017 |
| worm | Harmothoe | a Harmothoe species (unidentified) | 2 | 1940 |
| worm | Harmothoe impar | an annelid | 2 | 1996 |
| worm | Hediste diversicolor | Estuary Ragworm | 5 | 2017 |
| worm | Hirudinidae | a Hirudinidae species (unidentified) | 4 | 1993 |