3,306 articles
Orchid ecology and biogeography
Orchid ecology and biogeography is the study of where the orchid family grows and what threatens it; most of its 30,000 species are tropical epiphytes.
Orchid fleck dichorhavirus
Orchid fleck dichorhavirus (orchid fleck virus, OFV, Dichorhavirus orchidaceae) is a bipartite negative-sense RNA rhabdovirus causing chlorotic or necrotic spots in orchids worldwide, transmitted and replicated in Brevipalpus false spider mites.
Orchid mycorrhiza
Orchid mycorrhiza is the symbiosis between orchids and orchid mycorrhizal fungi (OMF), mainly rhizoctonias such as Tulasnella and Ceratobasidium, required by all orchids for seed germination, forming pelotons, and supporting autotrophic, mycoheterotrophic, and mixotrophic adult nutrition.
Orchid nothogenera and intergeneric hybrid genera
Orchid nothogenera are single-word names for hybrids between two or more orchid genera, such as × Doritaenopsis, governed by the ICN and registered with the RHS.
Orchid phytochemistry
Orchid phytochemistry is the study of the chemical compounds produced by orchids, including phenanthrenes, alkaloids, and vanillin; orchids are the plant kingdom's richest source of phenanthrenes.
Orchid pollination
Orchid pollination is the study of how the more than 29,000 orchid species transfer pollen in packaged pollinia, often deceiving pollinators instead of offering nectar rewards.
Orchid propagation
Orchid propagation is the human-managed reproduction of orchids by sterile seed culture, clonal micropropagation, and vegetative division, back-bulbs, and keikis, replacing natural germination that depends on mycorrhizal fungi.
Orchidaceae
Orchidaceae (orchids), one of the two largest flowering plant families with about 760 genera and 26,000 species, cosmopolitan except Antarctica, over 75% epiphytic, defined by resupinate zygomorphic flowers, a labellum, fused column, pollinia, and fungus-dependent microseeds.
Orchids of Africa
The orchids of Africa are the orchid species of continental sub-Saharan Africa and Madagascar, totaling over 2,000 species, with Central Africa richest and the chikanda tuber trade threatening many.
Orchids of Australia
The orchids of Australia are a native flora of roughly 1,700 to 2,000 species in about 116 genera, with 90 to 95% endemic and richest in the country's south-west.
Orchids of Europe
The orchids of Europe comprise about 1,000 species, subspecies, and varieties of Orchidaceae, concentrated in the Mediterranean, with high endemism, recent rapid speciation, and a quarter of assessed species threatened.
Orchids of Madagascar
The orchids of Madagascar are a highly endemic flora of about 1,000 species in 53 genera, famous for Darwin's 1862 prediction of a long-tongued hawkmoth pollinator.
Orchids of New Zealand
The orchids of New Zealand comprise about 117 species in 24 to 27 genera, mostly small terrestrial ground orchids, with greenhoods (Pterostylis) the largest genus.
Orchids of North America
The orchids of North America are the roughly 210 orchid species native north of Mexico plus about 2,670 Mesoamerican species, with richness rising steeply toward the tropics.
Orchids of South America
Orchids of South America covers the continent's orchid diversity: Colombia, Ecuador, and Brazil lead with thousands of species each, concentrated in the Andes and Atlantic Forest.
Orchids of subantarctic and oceanic islands
The orchids of subantarctic and oceanic islands are the exceptionally sparse orchid floras of remote islands, with Macquarie Island at 55°S marking the family's southernmost limit.
Orchids of the Caribbean
The orchids of the Caribbean are the roughly 600 to 728 orchid species native to the West Indies, where 42 to 72 percent of species grow nowhere else.
Orchids of the Pacific Islands
The orchids of the Pacific Islands are the orchid floras of Melanesia, Micronesia, and Polynesia in Oceania, where a survey of 63 islands found 552 species in 110 genera.
Orchis
Orchis (Tourn. ex L., 1753) is a genus of about 20 terrestrial Eurasian orchids in Orchidaceae, subtribe Orchidinae, type species O. militaris; formerly broader, now excluding Anacamptis and Neotinea, growing on calcareous soils.
Oregano
Oregano, chiefly Origanum vulgare (wild marjoram), a Lamiaceae perennial herb of the Mediterranean; flavor from carvacrol and thymol; Mexican oregano is Lippia graveolens; world trade exceeds 15,000 tonnes.
Origanum
Origanum is a Lamiaceae genus of about 40-44 aromatic species native from Macaronesia and Europe to Central China, 90% Mediterranean. Includes oregano (O. vulgare, cymyl/carvacrol chemotype) and sweet marjoram (O. majorana, sabinyl chemotype).
Ornamental alliums
Ornamental alliums are bulbous members of the genus Allium, grown in gardens for their spherical flower heads in late spring and early summer, with about 250 ornamental species and 240 cultivars in the trade.
Ornithogalum
Ornithogalum is a genus of bulbous flowering plants in the asparagus family, native from Europe to Afghanistan and southern Africa, known in gardens as star of Bethlehem.
Ornithopus
Ornithopus (bird's-foot, serradella) is a genus of six annual legume species in Fabaceae, tribe Loteae, native from Macaronesia and Europe to Iran and disjunctly to South America; O. sativus is a widely sown forage legume on acidic sandy soils.
Ornithopus sativus
Ornithopus sativus, known as French serradella or pink serradella, is an annual legume in the pea family, native to southwestern Europe and northwestern Africa and grown as forage.
Orobanchaceae
Orobanchaceae (broomrape family), Ventenat 1799, is the largest family of parasitic flowering plants in Lamiales, with over 2,000 species in about 90-115 genera, spanning non-parasitic, hemiparasitic, and holoparasitic members including Striga and Orobanche crop pests.
Orobanche
Orobanche (broomrapes), holoparasitic Orobanchaceae genus published 1753; chlorophyll-free root parasites on Asteraceae and other hosts; 174 species in 2025 broad circumscription; crop pests like O. crenata and O. cumana.
Orris root
Orris root: dried, aged rhizomes of Iris germanica, I. pallida, and I. florentina, source of violet-scented irones for perfume (orris butter) and gin flavoring; irones form only after 3–5 years of curing.
Orthosiphon
Orthosiphon (syn. Clerodendranthus) is a genus of 45 accepted Lamiaceae species native from Colombia and Africa to northeast Australia; its best-known species, O. aristatus or O. stamineus (cat's whiskers, misai kucing), is a Southeast Asian medicinal plant used as a diuretic and studied for antidiabetic effects.
Oryza
Oryza is a genus of grasses containing the two domesticated rices, Asian rice and African rice, plus wild relatives, native to the tropics and subtropics.