3,306 articles
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.
Rattan
Rattan (Malay rotan): about 600 spiny climbing palm species of the Old World tropics, mainly Calamus, whose solid flexible stems (cane) supply furniture and basketry; Southeast Asia's top forest product after timber.
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.
Ravenala
Ravenala, the traveller's palm or ravinala, is a Madagascan genus of Strelitziaceae; once monotypic with R. madagascariensis, it gained five new species in 2021 and is lemur-pollinated with blue-seeded arils.
Red rice
Red rice: rice (Oryza sativa) with a red pericarp from proanthocyanidins, governed by the Rc gene; eaten as an unpolished food in Asia and Africa, and in the US a name for weedy rice descended from crop-wild hybrids.
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.
Reseda
Reseda (mignonette genus, Resedaceae), about 65 Old World species centered on the Mediterranean; includes weld (R. luteola), the historic luteolin yellow dye plant, and fragrant R. odorata.
Resedaceae
Resedaceae, the mignonette family (type genus Reseda), is a small Brassicales family of herbs and shrubs producing glucosinolates, centered on the Mediterranean, with 6 traditional genera and about 60 species, 11 genera in modern circumscriptions.
Resin acid
Resin acids are tricyclic C20 diterpene monocarboxylic acids (C19H29COOH, MW 302) of abietane and pimarane skeletons that make up rosin, conifers' stored chemical defense.
Restionaceae
Restionaceae (restios), family of wind-pollinated, mostly dioecious perennial herbs of the Southern Hemisphere; 51 genera, 572 species per Kew; dominant in Cape fynbos and Australian kwongan; flowers year-round with spring peak.
Retrophyllum
Retrophyllum is a genus of six (or five) dioecious podocarp conifers with twisted, comb-like flattened leaves and red drupe-like seed cones, disjunctly distributed in South America and Australasia, with fossils from the Late Cretaceous to Miocene.
Reynoutria
Reynoutria Houtt. (1777), knotweed genus of Polygonaceae, native Russian Far East to East Asia; includes Japanese knotweed (R. japonica); synonymy with Fallopia disputed, molecular data support separate status.
Reynoutria japonica (イタドリ)
Reynoutria japonica (イタドリ, itadori; syn. Fallopia japonica, Polygonum cuspidatum), Japanese knotweed: an East Asian Polygonaceae perennial, IUCN 100-worst invader abroad, single female clone in Europe, spring vegetable in Japan.
Rhamnaceae
Rhamnaceae, the buckthorn family, is a Rosales family of trees, shrubs, and vines with c. 50-60 genera and 900-1,200 species, cosmopolitan, including Ziziphus jujubes, Rhamnus buckthorns, and Ceanothus ornamentals.
Rhamnus (plant)
Rhamnus (buckthorn) is a genus of about 139 accepted species of shrubs and small trees in Rhamnaceae, native to temperate and subtropical to tropical mountains, with drupes bearing 2-4 stones; R. cathartica is invasive in eastern North America.
Rhamnus alaternus
Rhamnus alaternus (Italian buckthorn, evergreen buckthorn) is a Mediterranean evergreen Rhamnaceae shrub, dioecious, with black 3-stoned drupes; used in North African folk medicine and invasive in California, Australia, and New Zealand.
Rhamnus cathartica
Rhamnus cathartica (common, European, or purging buckthorn) is a dioecious Eurasian Rhamnaceae shrub introduced to North America in the early 1800s as an ornamental and medicinal plant, now an invasive forest understory tree, alternate host of oat crown rust and the soybean aphid, with no approved biocontrol agents.
Rhinanthus minor
Rhinanthus minor, yellow rattle, is a hemiparasitic annual of Orobanchaceae native from Europe to western Siberia, parasitizing grasses via haustoria and used to create wildflower meadows; seeds rattle in its papery calyx.
Rhipsalis
Rhipsalis, the mistletoe cacti, is a genus of about 45 species of spineless epiphytic cacti native to tropical America, with R. baccifera reaching Africa and Sri Lanka.