2,112 articles
Osmanthus fragrans
Osmanthus fragrans (桂花, guìhuā), sweet osmanthus or tea olive, is an Oleaceae tree native from the Himalaya to southern Japan, cultivated in China for 2,500 years for fragrant flowers used in tea, sweets, medicine, and perfumery.
Osteospermum
Osteospermum, the daisybushes or African daisies, is a genus of 74 accepted species in Asteraceae tribe Calenduleae, native from St. Helena and Egypt to South Africa and Arabia, with hard, winged, pappus-less achenes and popular ornamental hybrids.
Osyris
Osyris (African sandalwood, Osyris lanceolata) is a genus of hemiparasitic shrubs in Santalaceae, tribe Osyrideae, published by Linnaeus in 1753; five accepted species ranging from the Mediterranean and Africa to southern Asia, distinct from Colpoon and Rhoiacarpos.
Oval Office Swedish ivy
Oval Office Swedish ivy: Plectranthus verticillatus, a South African mint-family trailer displayed on the White House Oval Office mantel from the Kennedy era until February 2025, now surviving through staffer cuttings.
Oxalidaceae
Oxalidaceae, the wood sorrel family (Oxalidales), is a nearly cosmopolitan flowering-plant family of 5 genera, Averrhoa, Biophytum, Dapania, Oxalis, and Sarcotheca, and roughly 570-800 species, including star fruit, bilimbi, and oca.
Oxalidales
Oxalidales (Bercht. & J.Presl 1820) is a rosid order of flowering plants in the COM clade, containing Oxalidaceae, Connaraceae, Brunelliaceae, Cephalotaceae, Cunoniaceae, and Elaeocarpaceae, with Huaceae now excluded by phylogenomic work.
Oxalis
Oxalis, commonly known as wood sorrel, is a large genus of flowering plants with clover-like leaves, five-petaled flowers twisted in the bud, and tissues rich in oxalic acid.
Oxalis acetosella
Oxalis acetosella, wood sorrel (Wald-Sauerklee, Alléluia), a small perennial Oxalidaceae herb of shady Eurasian woods, with white purple-veined flowers, sour oxalic-acid leaves, and a Europe-to-Japan native range.
Oxalis triangularis
Oxalis triangularis (purple shamrock, false shamrock; synonym Oxalis regnellii) is a tuberous South American wood sorrel grown as a houseplant, with triangular purple leaves that fold at night via nyctinastic pulvinus movement and tart edible foliage.
Oxydendrum
Oxydendrum, sourwood (Oxydendrum arboreum), a monotypic genus of Ericaceae; deciduous southeastern US tree with lily-of-the-valley-like white summer flowers, prized honey, red fall color, acid soil needs, IUCN Least Concern.
Oxyrhynchus
Oxyrhynchus (Oxyrhynchus Brandegee), a genus of twining Fabaceae legumes published in 1912; species include O. volubilis (twining bluehood) and O. papuanus, native from Mexico to Colombia, the Bahamas to Cuba, and Maluku to Papuasia.
Oxytropis
Oxytropis (locoweed genus) is a Fabaceae legume genus of about 400 species across subarctic and temperate Northern Hemisphere, distinguished from Astragalus by a pointed keel petal; some species carry swainsonine-producing endophytic fungi toxic to livestock.
Pachira aquatica
Pachira aquatica, the Guiana-chestnut or money tree, is a wetland Bombacoideae tree from Mexico to South America; type of its genus, edible seeds, braided houseplant form, Least Concern.
Pachycereus
Pachycereus, Mexican columnar cactus genus (Britton & Rose 1909) with five accepted species including the giant cardón Pachycereus pringlei, up to 20 m tall, bat-pollinated, native only to Mexico.
Pachyrhizus
Pachyrhizus is a genus of five Neotropical legume species known as yam beans, three cultivated for their edible tuberous roots, including the Mexican species jicama.
Paeonia lactiflora
Paeonia lactiflora (芍药, shaoyao), the Chinese or common herbaceous peony, is a temperate perennial native to SE Siberia and N & E China, grown as an ornamental and cut flower and used in TCM as Bai Shao root, source of paeoniflorin.
Paliurus
Paliurus (Jerusalem thorn) is a genus of five spiny shrub and tree species in Rhamnaceae, tribe Paliureae, native from southern Europe and southwest Asia to East Asia, recognized by dry orbicular-winged wind-dispersed fruits and a rich Northern Hemisphere fossil record.
Panax
Panax (人参属) is the ginseng genus of Araliaceae, published by Linnaeus in 1753 with 15 accepted species native from the Himalaya to Japan and eastern North America; it includes P. ginseng, P. quinquefolius, and P. notoginseng, key medicinal herbs containing ginsenosides.
Panax ginseng
Panax ginseng (인삼, Asian or Korean ginseng), a slow-growing Araliaceae herb native to Korea, northeastern China, and far-eastern Siberia; its ginsenoside-containing root is a widely used supplement with no conclusive clinical evidence for treating any disease.
Panax notoginseng
Panax notoginseng (三七, Sanqi, Tianqi, notoginseng) is a threatened perennial Araliaceae herb native to SE Yunnan and N. Vietnam, cultivated over 400 years in Wenshan; its saponins (ginsenosides R1, Rb1, Rd, Rg1, Re) are used in traditional Chinese medicine and tested for stroke, angina, and kidney disease.
Pando (tree)
Pando (Latin "I spread"), the trembling giant, is a single male quaking aspen clone in Fishlake National Forest, Utah: about 47,000 genetically identical stems across 106 acres, roughly 13 million pounds, and estimated 12,000–80,000 years old.
Papaver
Papaver (poppies) is a genus of 66 accepted species in Papaveraceae, order Ranunculales, native to temperate and subtropical Northern Hemisphere and southern Africa. Includes opium poppy P. somniferum, source of morphine and codeine, and common poppy P. rhoeas.
Papaver rhoeas
Papaver rhoeas, the common or corn poppy (Flanders poppy), is an annual Papaveraceae herb with scarlet 7–10 cm flowers, globose capsules, seeds dormant over 80 years, no opium alkaloids, and the World War I remembrance symbol.
Papaver somniferum
Papaver somniferum, the opium poppy or breadseed poppy, is an annual Papaveraceae herb from the western Mediterranean, sole source of opium alkaloids (morphine, codeine, thebaine) and grown for edible poppy seeds; 2n=22, IUCN Least Concern.
Papaveraceae
Papaveraceae, the poppy family (formerly including Fumariaceae), is a Ranunculales eudicot family of about 41-46 genera and roughly 700 species with milky latex, capsule fruits, and over 540 isoquinoline alkaloids, including the opium poppy Papaver somniferum.
Papaya
Papaya (Carica papaya, pawpaw, fruta bomba) is a tropical Caricaceae fruit tree from Mesoamerica with XY/XYh sex chromosomes, papain-rich fruit, and PRSV-resistant transgenic Rainbow cultivars in Hawaii.
Paprika
Paprika: ground spice from dried Capsicum annuum fruits; also called pimentón in Spain. Etymology from Slavic papar via Hungarian; key origins Szeged, Kalocsa, La Vera; quality set by carotenoid color and capsaicin heat.
Paraserianthes lophantha
Paraserianthes lophantha (crested wattle, plume albizia, stink bean) is the sole species of its mimosoid legume genus, native to SW Australia and Sumatra-Java-Lesser Sundas, with two subspecies, fire-stimulated hard seeds, and invasive status in South Africa, New Zealand and Australia.
Parasitic plant
Parasitic plants, also called hemiparasites and holoparasites, are flowering plants that steal water and nutrients from hosts via a haustorium; about 4,750 species, 12 independent origins, including Striga, Orobanche, Cuscuta, and Rafflesia.
Parietaria
Parietaria (pellitory, pellitory-of-the-wall) is a genus of about 26 Urticaceae herbs in Rosales that grows in old walls and cracks; its long-season, wind-dispersed pollen is a leading cause of allergic rhinitis and asthma in the Mediterranean.