Plants and algae

Roselle (plant)

Roselle (Hibiscus sabdariffa, karkade, red sorrel, Florida cranberry) is a Malvaceae shrub grown for its red calyces used in tea, jam, and coloring; major producers China, Sudan, Thailand; lowers blood pressure in trials.

Rosemary

Rosemary (Salvia rosmarinus, formerly Rosmarinus officinalis) is an aromatic evergreen shrub of the mint family native to the Mediterranean, grown worldwide as a culinary herb and source of essential oil.

Rosids

Rosids: a major eudicot clade of flowering plants with about 140 families and one-third of angiosperm species, split into fabids and malvids, crown age 115-93 Mya, recircumscribed in APG V.

Rosin

Rosin (colophony) is the glassy solid left after turpentine is distilled from pine oleoresin; gum, wood, and tall oil grades; used for bow friction, soldering flux, paper sizing, and drug delivery.

Rotala

Rotala (rotala, dwarf rotala, roundleaf toothcup) is a genus of about 71–75 aquatic herbs in Lythraceae, established by Linnaeus in 1771; R. rotundifolia is a Category II invasive weed in south Florida and a popular aquarium plant.

Rowan

Rowan, also called mountain ash, is a small deciduous tree of the rose family, native to Europe and temperate Asia, known for its bright red autumn berries.

Roystonea regia

Roystonea regia, the Cuban royal palm (palma real), is a large Arecaceae palm native to southern Florida, Mexico, Central America, and the Caribbean, Cuba's national tree, reaching 34.5 m, IUCN Least Concern, widely planted ornamentally and used for oil, feed, and thatch.

Rubia

Rubia (madder), Old World Rubiaceae genus of about 80-87 species including R. tinctorum and R. cordifolia; roots yield alizarin and purpurin red dyes used since antiquity and in traditional medicine.

Rubia tinctorum

Rubia tinctorum (dyer's madder), a Rubiaceae perennial native from SE Europe to Xinjiang, whose alizarin- and purpurin-rich roots have dyed textiles red since 2000 BC; synthetic alizarin (1868) largely replaced it.

Rubiaceae

Rubiaceae, the coffee or madder family (Gentianales), is the fourth-largest angiosperm family with about 586 accepted genera and over 14,000 species, defined by interpetiolar stipules and inferior ovaries; includes Coffea, Cinchona, Gardenia, and Psychotria.

Rubus

Rubus is the rose-family genus of blackberries, raspberries, and brambles, with roughly 700 to over 1400 species, biennial prickly canes, aggregate drupelet fruits, apomixis, and polyploid, hybrid-driven taxonomy revised into 10 subgenera in 2023.

Rubus caesius

Rubus caesius L., the European dewberry, is a scrambling Rosaceae shrub native from Europe to Xinjiang and the W. Himalaya, with trailing glaucous stems, white flowers, and bluish-black few-drupelet fruit.

Rubus chamaemorus

Rubus chamaemorus, the cloudberry (hjortron, bakeapple, aqpik), is a dioecious circumboreal bog herb of Rosaceae with amber aggregate fruits, rich in vitamin C and ellagitannins, harvested wild across Scandinavia and North America.

Rubus fruticosus

Rubus fruticosus L. (blackberry, bramble, Rubus fruticosus agg.) is a European Rosaceae scrambling shrub published by Linnaeus in 1753; an apomictic aggregate of over 2,000 microspecies, cultivated for its black drupelet fruit and used in food and herbal medicine.

Rubus idaeus

Rubus idaeus, red raspberry or wild raspberry, a Rosaceae shrub of the temperate Northern Hemisphere to Mexico; diploid 2n=14, two subspecies (idaeus, strigosus), two-year cane cycle, grown for fruit and herbal medicine.

Rubus leucodermis

Rubus leucodermis, whitebark or western black raspberry, is a western North American Rosaceae shrub with whitish waxy canes, black raspberries, two varieties, and use in black raspberry breeding for RBDV resistance.

Rubus occidentalis

Rubus occidentalis, black raspberry or blackcap, a North American Rosaceae bramble (subgenus Idaeobatus, 2n=14) grown mainly in Oregon, with anthocyanin-rich fruit distinct from red raspberry and blackberry.

Rubus phoenicolasius

Rubus phoenicolasius (wineberry, Japanese wineberry) is an East Asian Rosaceae shrub introduced to the US in 1890 for breeding, now invasive in the eastern US, with red-hairy canes, edible fruit, tip-rooting, and higher competitive ability than native blackberries.

Rudbeckia

Rudbeckia, commonly called coneflowers or black-eyed Susans, is a genus of about 30 daisy-family flowering plants native to North America, with yellow or orange rays around a raised dark central cone.

Rudbeckia hirta

Rudbeckia hirta, black-eyed Susan or gloriosa daisy, is a North American Asteraceae forb, annual to short-lived perennial, with yellow ray flowers and a dark cone; Maryland's state flower since 1918, with four varieties and many cultivars.

Rudbeckia laciniata

Rudbeckia laciniata, cutleaf coneflower or sochan, a North American perennial Asteraceae with cut leaves, edible young leaves, livestock toxicity, and invasive status in Europe and Japan.

Ruellia

Ruellia (wild petunia), a large genus of Acanthaceae flowering plants published by Linnaeus in 1753, with about 375-388 species native to tropics, subtropics, and North America; type species Ruellia tuberosa.

Rumex

Rumex (docks and sorrels) is a genus of about 200 Polygonaceae herbs with six-part flowers, accrescent inner perianth valves, and trigonous nuts; some dioecious species have heteromorphic sex chromosomes.

Rumex crispus

Rumex crispus (curly dock, yellow dock) is a perennial Polygonaceae herb native to temperate Eurasia and now a global weed; about 224 phytochemicals, traditional laxative and astringent uses, oxalate and emodin toxicity.

Rumex obtusifolius

Rumex obtusifolius, broad-leaved dock or bitter dock, a perennial Polygonaceae weed native to Europe to Central Siberia and Iran, invasive in pastures worldwide; up to 60,000 seeds yearly, oxalic acid, controlled via Pyropteron biocontrol.

Runcaria

Runcaria, scientifically Runcaria heinzelinii, is a fossil plant reproductive structure from Middle Devonian Belgium, about 385 million years old, and the earliest known evidence of the seed habit.

Ruppia

Ruppia (widgeon grass, ditch-grass) is the sole genus of Ruppiaceae, submerged brackish-water monocots with hydrophilous pollination, cosmopolitan distribution, salinity tolerance from freshwater to hypersaline, and disputed species limits (4-12 species).