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Quercus douglasii
Quercus douglasii, the blue oak (also iron oak, mountain white oak), is a drought-deciduous California endemic oak dominating foothill woodlands around the Central Valley; IUCN Least Concern, but low recruitment and projected range loss under climate change concern conservationists.
Quercus ilex
Quercus ilex, holm or holly oak, an evergreen Mediterranean oak of Fagaceae, dominant in dehesa woodlands; over 2 million ha, two subspecies (ilex, ballota), low-rate hybridization with cork oak, drought-tolerant anisohydric physiology.
Quercus nigra
Quercus nigra (water oak, possum oak) is a fast-growing red-group oak of the southeastern US Coastal Plain and bottomlands, with spatulate leaves, small biennial black acorns, weak wood, and wide use as a southern street tree.
Quercus palustris
Quercus palustris, the pin oak (also swamp oak, water oak), is a fast-growing red oak of eastern North American bottomlands, 50–70 ft tall, requiring acid soil and developing iron chlorosis on alkaline sites.
Quercus petraea
Quercus petraea, the sessile or durmast oak, is a large European oak native to Europe and N. Iran, distinguished from Q. robur by stalkless acorns and long leaf stalks, drought-tolerant, and valued for timber and barrels.
Quercus pubescens
Quercus pubescens (downy oak, pubescent oak), a polymorphic European white oak with hairy leaves and twigs, native from France to Türkiye, xerophilous on chalky soils, hybridizing with Q. petraea and Q. robur.
Quercus robur
Quercus robur (English or pedunculate oak), a 20-40 m Fagaceae tree native from Europe to Iran, Britain's iconic oak, hybridizing with Q. petraea, timber for ships and Westminster Hall, IUCN Least Concern.
Quercus rubra
Quercus rubra, northern red oak (dąb czerwony, chêne rouge), a large deciduous oak native to eastern North America, introduced to Europe in 1691; fast-growing timber and ornamental tree, drought-tolerant, invasive in Central Europe, susceptible to oak wilt.
Quercus stellata
Quercus stellata, post oak or iron oak, a slow-growing white oak of the southeastern and south-central US, drought-resistant on dry uplands, living 300-400 years, with fencepost wood and Cross Timbers pure stands.
Quercus suber
Quercus suber, the cork oak, is an evergreen oak of the western and central Mediterranean whose bark is stripped periodically and regrown, chiefly for wine stoppers.
Quercus variabilis
Quercus variabilis (栓皮栎), the Chinese cork oak or oriental oak, is an East Asian deciduous oak to 30 m with thick corky bark, cork and tannin uses, IUCN Least Concern status, and a 787 Mb genome.
Quercus velutina
Quercus velutina, black oak or yellow oak, is a deciduous eastern North American red oak of dry upland slopes, with black furrowed bark, yellow bitter inner bark (quercitron dye), biennial acorns, and wood sold as red oak.
Quercus virginiana
Quercus virginiana, the southern live oak (Virginia live oak), is a nearly evergreen southeastern US coastal plain oak with crowns to 150 ft, extremely dense wood used in USS Constitution shipbuilding, high salt tolerance, and G5/LC conservation status.
Rafflesia
Rafflesia, the corpse flower genus (Rafflesiaceae), is a Southeast Asian holoparasite on Tetrastigma vines with no leaves, stems, or roots; R. arnoldii bears the world's largest single flower, up to 1 m and 7 kg, smelling of rotting meat.
Rafflesia arnoldii
Rafflesia arnoldii (corpse flower, padma raksasa) is a holoparasitic Sumatran and Bornean plant on Tetrastigma vines, producing the world's largest single flower, up to 1 m across, smelling of rotting meat and pollinated by carrion flies.
Ragweed
Ragweed (Ambrosia, Asteraceae), including common ragweed Ambrosia artemisiifolia, is a North American wind-pollinated weed whose highly allergenic pollen causes hay fever; it invaded Europe via multiple introductions and contaminated grain, costing billions annually.
Rambutan
Rambutan (Nephelium lappaceum, Vietnamese Chom Chom, Thai Ngo) is a Sapindaceae tropical tree from southern China to Malesia with hairy red fruit, sweet aril, 1.4 Mt annual Southeast Asian production, Indonesia largest producer.
Ranunculaceae
Ranunculaceae, the buttercup family, is an early-diverging eudicot family in Ranunculales with about 49 accepted genera including Ranunculus, Clematis, Aconitum, Delphinium, and Pulsatilla, mostly temperate northern hemisphere herbs used in horticulture and medicine.
Ranunculales
Ranunculales, an order of flowering plants and the sister lineage to all other eudicots, with about 4,500 mainly temperate species in seven APG IV families including Ranunculaceae, the buttercup family.
Ranunculus
Ranunculus (buttercups), largest genus of Ranunculaceae, first published by Linnaeus in 1753; Kew lists 1788 species distributed on all continents, with yellow or white flowers, achenes, and ranunculin-derived protoanemonin toxicity.
Ranunculus bulbosus
Ranunculus bulbosus, the bulbous buttercup, is a perennial herb in the buttercup family that regrows from a bulbous stem base and is native from Morocco across Europe to Central Asia.
Rapeseed
Rapeseed (Brassica napus, B. rapa, B. juncea), also called colza or canola when low-erucic, is a major oilseed: ~42% oil, second most produced edible oil, meal 36-38% protein, industrial erucic-acid uses.
Rapeseed oil
Rapeseed oil (canola oil, from Canadian oil, low acid) is oil from Brassica napus and related seeds, bred below 2% erucic acid; global production about 37 million metric tons, used for food, feed, and biofuel.
Raphanus
Raphanus (radish genus), Brassicaceae tribe Brassiceae; includes Raphanus sativus (radish) and R. raphanistrum (wild radish); shown polyphyletic, with sect. Hesperidopsis proposed as genus Quidproquo.
Raphanus raphanistrum
Raphanus raphanistrum (wild radish, jointed charlock), a Brassicaceae annual native to Europe through Central Asia and ancestor of the cultivated radish; a major Australian crop weed with widespread multiple herbicide resistance and seeds viable up to 20 years.
Raspberry
Raspberry (Rubus idaeus, European red raspberry) is a Rosaceae shrub whose fruit is an aggregate of drupelets, hollow when picked. Native to temperate Eurasia and North America; bee-pollinated; Russia led 2024 production with 213,818 tonnes.
Ratibida columnifera
Ratibida columnifera, upright prairie coneflower or Mexican hat, is a native Great Plains perennial forb in Asteraceae with a columnar flower disk, yellow to maroon rays, used in prairie restoration.
Rauvolfia serpentina
Rauvolfia serpentina (Indian snakeroot, sarpagandha), an Apocynaceae shrub of South Asia whose reserpine-rich roots were major antihypertensive and sedative drugs; endangered by over-exploitation.
Redcurrant
Redcurrant (Ribes rubrum L.) is a western European Grossulariaceae shrub bearing translucent red berries in clusters; white and pink currants are its variants. Domesticated from the 1400s, Dutch-bred, grown for juice, jam, and wine.
Rehmannia glutinosa
Rehmannia glutinosa (地黄, dihuang, Chinese foxglove) is a Chinese perennial herb whose tuberous root, used fresh, dried, or steamed, is a major traditional medicine; over 310 constituents including catalpol are documented.