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Hippophae rhamnoides
Hippophae rhamnoides, sea buckthorn (Elaeagnaceae), a hardy nitrogen-fixing Eurasian shrub with seven subspecies, orange vitamin-rich berries used in food and traditional medicine, and limited clinical evidence of benefit.
History of cannabis
History of cannabis (Cannabis sativa): Eurasian domestication for fiber, food, and medicine; earliest psychoactive use at Jirzankal Cemetery; O'Shaughnessy's 19th-century medical promotion; 1925 Geneva control, 1937 US Marijuana Tax Act, and modern legalization.
History of maize
The history of maize traces its single domestication from wild teosinte in Mexico's Balsas River valley about 9,000 years ago, its spread through the Americas, and its global rise after 1492.
History of the potato
History of the potato (Solanum tuberosum): Andean domestication ~10,000 years ago, sixteenth-century Spanish introduction to Europe, Chilean subspecies adoption, the Great Irish Famine, demographic effects, and modern genome-based breeding.
History of wheat
Wheat, first domesticated in the Fertile Crescent around 10,000 years ago, gave rise to bread wheat by hybridization 8,500 to 9,000 years ago and became the world's most widely grown crop.
Höganäs Formation
Höganäs Formation (Höganäsformationen), Rhaetian–Hettangian (Upper Triassic–Lower Jurassic) mudstone, sandstone and coal unit in Skåne, southern Sweden; Vallåkra, Bjuv, Helsingborg members; coal mined until 1961; rich Rhaetian floras.
Hoh Rainforest
Hoh Rainforest, in Olympic National Park, Washington, is an old-growth temperate rainforest on the Hoh River receiving about 140 inches of rain yearly, known for the Hall of Mosses trail, moss-draped giants, and its 2025 road-washout closure.
Holcus
Holcus (velvetgrass) is a small genus of annual and perennial Poaceae grasses, tribe Poeae, subtribe Holcinae, native from Macaronesia and Europe to the Caucasus and South Africa; type species Holcus lanatus, Yorkshire fog, a forage grass and weed.
Holcus lanatus
Holcus lanatus, Yorkshire fog or velvet grass, is a tufted perennial grass native to Europe, Macaronesia, and the Caucasus, naturalized worldwide, a prolific seeder, pasture forage, lawn weed, and invasive in California coastal prairies.
Holcus mollis
Holcus mollis (creeping soft grass) is a rhizomatous perennial Poaceae grass native to Europe and NW Africa, with chromosome races 2n=28, 35, 42, 49, exserted awns, and bearded nodes, distinct from Holcus lanatus.
Holly
Holly (Ilex, Aquifoliaceae): the sole genus of its family, over 664 dioecious tree and shrub species. Originated in subtropical Asia in the early Eocene; famous species include Ilex aquifolium, the Christmas holly.
Holodiscus discolor
Holodiscus discolor, oceanspray or creambush (Rosaceae), a deciduous arching shrub native from British Columbia to Mexico, with creamy white flower sprays, four varieties, fire-adapted, valuable to native bees.
Honey locust
Honey locust (Gleditsia triacanthos), also called sweet-locust or thorny-locust, is a thorned North American legume tree with sweet pods, thornless urban cultivars, and invasive populations in Argentina, Europe, and Australia.
Honeysuckle
Honeysuckle, genus Lonicera (Caprifoliaceae), about 160 Northern Hemisphere species of fragrant vines and shrubs; Japanese honeysuckle (Lonicera japonica) is a major invasive vine in North America, while Lonicera sempervirens is a native alternative.
Hopea
Hopea is a genus of about 100 dipterocarp timber trees from Sri Lanka to New Guinea, known as merawan timber, distinguished from Shorea by two long fruit calyx wings and nested phylogenetically within Shorea.
Hops
Hops, the female cones of Humulus lupulus (Cannabaceae), are the brewing crop that bitters, flavors, and preserves beer via alpha acids and essential oils; cultivated since the 8th-century Hallertau, with over 260 varieties and medicinal uses.
Hordeum
Hordeum (barleys), a genus of Triticeae grasses in Poaceae, includes cultivated barley Hordeum vulgare, the fourth most grown cereal, domesticated about 10,000 years ago from H. spontaneum; recognized by triplet spikelets and x=7 chromosomes.
Hordeum murinum
Hordeum murinum, wall barley or false barley, a weedy annual grass with three subspecies (glaucum, leporinum, murinum) native from Europe to the Himalaya, now a herbicide-resistant crop and pasture weed harming sheep worldwide.
Hornbeam
Hornbeam (Carpinus), a birch-family hardwood genus of about 19-40 Northern hemisphere species; European hornbeam (C. betulus) is a 25 m coppice and hedging tree of heavy lowland soils, with very hard wood used for cogs and mallets.
Horseradish
Horseradish (Armoracia rusticana), a Brassicaceae perennial from southeastern Europe and western Asia, grown over 3,000 years for its pungent taproot; allyl isothiocyanate from sinigrin gives the heat, and it substitutes for wasabi.
Hosta
Hosta, or plantain lily, is a genus of shade-loving foliage perennials in Asparagaceae native to East Asia, introduced to the West by von Siebold in 1829-1830, with thousands of registered cultivars and slugs and Hosta Virus X as chief problems.
Houstonia caerulea
Houstonia caerulea, the azure bluet or Quaker ladies, is a small wildflower of the madder family native to eastern North America, with pale blue, four-lobed spring flowers.
Houttuynia cordata
Houttuynia cordata (chameleon plant, fish mint, yu xing cao) is an Asian Saururaceae herb eaten as a vegetable, used in traditional Chinese medicine, studied for anti-inflammatory and antiviral effects, and invasive outside its native range.
Humulus
Humulus (hops genus) is a Cannabaceae genus of dioecious twining herbs native to the temperate Northern Hemisphere, with 7 accepted species; H. lupulus cones supply beer bitterness, aroma, and preservation.
Humulus lupulus
Humulus lupulus, common hop, is a dioecious perennial Cannabaceae vine whose female cones (strobili) supply beer's bitterness and aroma; ~97% of production goes to brewing, with humulone, xanthohumol, and 8-prenylnaringenin as key compounds.
Hura crepitans
Hura crepitans, the sandbox tree or jabillo, is a spiny Euphorbiaceae tree native to tropical America with toxic sap and explosive fruit capsules that launch seeds at about 43 m/s up to 45 m.
Hushpuppy
Hushpuppy: small deep-fried balls of seasoned cornmeal batter, a Southern US side dish served with fried fish, seafood, and barbecue; name traced to Carolinas and Georgia fish fries, with dog-feeding origin stories.
Husk
Husk: the dry outer covering of seeds, grains, or fruits (also hull, chaff); in maize, modified leaves protecting the ear, photosynthesizing, and enabling kernel drydown; from late 14c. English huske.
Hyacinth
Hyacinthus (hyacinth) is a small Asparagaceae bulb genus from southern Türkiye to northern Israel and southern Turkmenistan, with three accepted species; the garden hyacinth derives entirely from Hyacinthus orientalis, though molecular work makes the genus polyphyletic.
Hyacinthoides non-scripta
Hyacinthoides non-scripta, the English or common bluebell, is a bulbous Asparagaceae geophyte native to western Europe, with scented one-sided violet-blue spring flowers; UK-protected, threatened by hybridization with H. hispanica.