2,112 articles
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.
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.
Rhizome
Rhizome: a horizontally growing modified plant stem at or just below the soil surface, bearing buds and roots at nodes; examples include iris, bamboo, and ginger; distinct from bulbs, corms, tubers, and stolons.
Rhizophora
Rhizophora is a genus of six accepted mangrove tree species in Rhizophoraceae, including the red mangrove R. mangle, defined by prop roots, over 90% root salt exclusion, and buoyant viviparous propagules that disperse by floating.
Rhizophora apiculata
Rhizophora apiculata (kongkang) is an Indo-West Pacific mangrove tree of Rhizophoraceae, dominant on estuarine mud from South Asia to Queensland, parent of two hybrids, used for charcoal and wood, IUCN Least Concern.
Rhizophora mangle
Rhizophora mangle, the red mangrove, is a viviparous stilt-rooted evergreen tree of tropical intertidal coasts of America and West Africa, tolerating 0-90 ppt salinity, IUCN Least Concern, invasive in Hawaii and Queensland.
Rhizophora mucronata
Rhizophora mucronata, Asiatic or loop-root mangrove (Rhizophoraceae), is a viviparous Indo-Pacific mangrove tree to 25 m with stilt roots and pointed leaves; bark yields tannin, parts serve traditional medicine, and it is IUCN Least Concern.
Rhizophoraceae
Rhizophoraceae, the red mangrove family, is a mainly Old World tropical family of 15–16 genera and about 145 species in Malpighiales, including about half of the world's true mangrove species.
Rhodiola rosea
Rhodiola rosea (rosenroot, arctic root, golden root), Crassulaceae succulent perennial of the subarctic Northern Hemisphere; root used traditionally as an adaptogen for stress and fatigue; EU traditional-use monograph; clinical evidence inconclusive; wild stocks overharvested.
Rhododendron
Rhododendron, including azaleas, is a large Ericaceae genus of 850+ woody species native from the temperate Northern Hemisphere to tropical Asian mountains and NE Australia, with leathery leaves, showy bell-shaped flowers, and winged seeds.
Rhododendron ferrugineum
Rhododendron ferrugineum, the alpenrose or alpine rose, is a dwarf evergreen Ericaceae shrub of the European Alps and Pyrenees, the type species of Rhododendron, flowering rosy scarlet at 1,700–2,500 m on acid, non-limestone soils.
Rhododendron ponticum
Rhododendron ponticum, an evergreen Ericaceae shrub native to the Black Sea region and Iberia, introduced to Britain in 1763, now one of the most destructive invasive plants of the British Isles, forming dense thickets and hosting Phytophthora ramorum.
Rhus typhina
Rhus typhina (staghorn sumac, Rhus hirta) is a suckering North American shrub or small tree of Anacardiaceae, 15-25 ft tall with velvety branches and red hairy fruit; harmless, unlike poison sumac (Toxicodendron vernix), and a 17th-century European introduction.
Ribes
Ribes (currants and gooseberries) is a genus of about 195 accepted shrub species in Grossulariaceae, native from subarctic to tropical American mountains, cultivated for black, red, and white currants and gooseberries, and alternate host of white pine blister rust.
Richardia brasiliensis
Richardia brasiliensis (tropical Mexican clover, Brazil pusley), a prostrate Rubiaceae herb native from Ecuador to northern Argentina, naturalized as a weed of turf, soybean, and corn across Florida, Australia, Asia, and Africa.
Ricinus
Ricinus, castor bean or castor oil plant (Ricinus communis L.), sole species of its Euphorbiaceae genus, native to NE tropical Africa, domesticated ~3200 years ago; seeds yield ricinoleic-acid-rich castor oil and the toxin ricin.
Ripening
Ripening, also known as fruit ripening, is the final phase of fruit maturation, a hormonally regulated process of pigment accumulation, softening, and aroma development; climacteric fruits like bananas ripen after harvest, while strawberries do not.
Robinia pseudoacacia
Robinia pseudoacacia, black locust or false acacia, is a fast-growing, nitrogen-fixing North American tree introduced to Europe in the early 17th century, widely planted for durable wood and honey yet ranked among Europe's 100 most invasive alien species.
Root
Root (botany): the plant organ that anchors the plant and absorbs water and minerals. Also called taproot or fibrous root systems; evolved independently in at least two vascular plant lineages in the Early Devonian, c. 410-395 million years ago.
Root vegetable
Root vegetable: culinary category of edible underground storage organs, including taproots (carrot, beet), tuberous roots (sweet potato), stem tubers (potato), corms, rhizomes, and bulbs; starchy staple crops central to food security.
Rorippa
Rorippa is a genus of 88 accepted species of often aquatic herbs in the mustard family, known as yellowcresses, first described by Scopoli in 1760.
Rosa bella
Rosa bella (美蔷薇, mei qiang wei) is a Chinese rose species, Rosaceae, described by Rehder & Wilson in 1915; a 1–3 m shrub of north and east China with pink flowers, red hips, and uses in oils, jam, and medicine.