Plants

Nightshade (Solanaceae): overview, chemistry, uses and risks Nightshade Nightshades (Solanaceae) are a diverse family of flowering plants that include important crops, ornamentals and toxic species. They are notable for alkaloids, varied fruits, and cu…

Noble orchid (Cymbidium goeringii): description, history and cultivation Noble orchid Cymbidium goeringii, the noble orchid, is a small cold-hardy East Asian orchid grown for spring flowers and fragrance. This article covers its features, range, cultural history, an…

Non-vascular plants: characteristics, groups, and ecological roles Non-vascular plant Plants that lack xylem and phloem; chiefly bryophytes (mosses, liverworts, hornworts). Overview of traits, life cycle, habitats, ecological importance, and differences from vascula…

Nothofagus (southern beech): overview, distribution, and significance Nothofagus Nothofagus, the southern beech, is a genus of about 34 species of trees and shrubs found across southern continents; notable for Gondwanan distribution, ecological dominance in tem…

Nuclear power plant: operation, components, history and global role Nuclear power plant Comprehensive overview of nuclear power plants: how they generate electricity, main components, fuel and waste management, safety, notable accidents, and their economic and environ…

Plant Nurseries: Types, Practices, and Role in Horticulture Nursery (horticulture) An overview of horticultural nurseries: their types, propagation methods, history, uses in landscaping and conservation, and regulatory and commercial distinctions.

Nut (fruit): botanical definition, culinary uses, and distinctions Nut (fruit) A nut is a hard, indehiscent fruit with a single seed enclosed in a woody shell. The word 'nut' is also used in cooking for many seeds and kernels. This article explains definition…

Nutmeg: the spice, the tree, and its uses Nutmeg Nutmeg (Myristica fragrans) is an aromatic seed and spice from an evergreen tropical tree valued in cooking, perfumery, and traditional medicine; it also carries allergy and toxici…

Nyctaginaceae — the four-o'clock family Nyctaginaceae Nyctaginaceae is a family of about 33 genera and 290 species of mainly tropical and subtropical flowering plants, known for bougainvillea, four-o'clocks and the distinctive anthoca…

Nymphaea — water-lilies: description, ecology, cultivation, and cultural role Nymphaea Nymphaea is a genus of floating aquatic plants (water-lilies) in the family Nymphaeaceae, grown in ponds and lakes worldwide for ornament, ecology, and cultural importance.

Nymphaea nouchali (blue star water-lily) Nymphaea nouchali A freshwater water-lily native to southern and eastern Asia, valued for star-shaped blue flowers, edible rhizomes, cultural significance, and use in ponds and aquaria.

Nymphaea pubescens — hairy water lily (pink water-lily) Nymphaea pubescens A tropical water-lily (Nymphaea pubescens) with pink to white flowers and hairy petioles, found in South and Southeast Asian ponds and wetlands; used ornamentally and in cultural s…

Nymphaeaceae (water-lily family) Nymphaeaceae Nymphaeaceae, the water-lily family, is an aquatic group of basal flowering plants known for floating leaves and showy flowers; widespread in freshwater habitats and placed near th…

Nymphaeales (water lilies and related aquatic plants) Nymphaeales An order of mostly aquatic flowering plants including water lilies and fanworts; an early-diverging lineage of angiosperms with floating leaves, radial flowers, and a fossil record…

Oak (Quercus): characteristics, uses, ecology and cultural role Oak Overview of the oak (genus Quercus): species, appearance, life cycle, wood and uses, ecological importance, history, and notable distinctions including live oaks and acorns.

Ocimum tenuiflorum (Tulsi) — holy basil plant Ocimum tenuiflorum Ocimum tenuiflorum, commonly called Tulsi or holy basil, is a sacred aromatic plant in the mint family used in Hindu worship, traditional medicine, and as a culinary herb in South…

Oenothera (evening primrose): overview, characteristics, history and uses Oenothera Oenothera, commonly called evening primrose, is a genus of about 125 species in the family Onagraceae. Native to the Americas, it has horticultural, ecological, medicinal and histo…

Oklahoma Rose: the hybrid tea rose of Oklahoma Oklahoma Rose A hybrid tea rose developed at Oklahoma State University in 1964 by Herbert C. Swim and O. L. Weeks; designated Oklahoma's state flower in 2004. Known for well-formed blooms and ho…

Okra (Abelmoschus esculentus): description, cultivation, culinary and cultural uses Okra Okra, or lady's fingers/gumbo, is a warm-season flowering plant grown for edible seed pods used worldwide in soups, stews and fried dishes; valued for its mucilage, fiber and adapt…

Olea capensis — African black ironwood Olea capensis Olea capensis (black ironwood) is a widespread African olive-family tree known for exceptionally dense, hard timber used for turnery, carving and durable small wooden objects.

Oleaceae (Olive Family): Taxonomy, Characteristics, and Uses Oleaceae Overview of Oleaceae (olive family): taxonomy, key traits, global distribution, notable genera (olive, ash, lilac, privet), and their economic, ornamental and ecological uses.

Oleander (Nerium oleander) — ornamental, toxic Mediterranean shrub Oleander Oleander is an evergreen ornamental shrub (Nerium oleander) valued for showy flowers and drought tolerance. Native to the Mediterranean region, it is highly toxic and has been stud…

Olive (Olea europaea): fruit, tree, oil, and cultural importance Olive Overview of the olive (Olea europaea): botany, cultivation, harvest and processing for table olives and olive oil, common uses, varieties, pests, sustainability and cultural signif…

Olive tree (Olea europaea) Olive tree Olea europaea, the olive tree, is an evergreen Mediterranean tree valued for its fruit, oil, wood and cultural significance. It is drought‑tolerant, long‑lived, and adapted to rock…

Olmedilla Photovoltaic Park Large ground-mounted photovoltaic power plant near Olmedilla de Alarcón, Spain. Commissioned in 2008 with about 60 MWp and over 160,000 panels; an early example of utility-scale so…

Onagraceae — the Evening-Primrose and Willowherb Family Onagraceae Onagraceae is a family of flowering plants (order Myrtales) that includes evening-primroses, willowherbs, fuchsias and water-primroses. Characteristic features include mostly four-…

Onion — Allium cepa: overview, characteristics, uses and history Onion Onion (Allium cepa) is a widely cultivated edible bulb known for its pungent flavor. This article covers its biology, varieties, history, culinary uses, nutrition and practical han…

Opium: composition, history, uses, and social impacts Opium Opium is the dried latex from Papaver somniferum poppies. This article explains its chemistry, historical use, medical role, health risks, production and the social/legal issues su…

Opium poppy (Papaver somniferum): biology, history, and uses Opium poppy An overview of the opium poppy (Papaver somniferum): its botanical features, alkaloids, cultivation, historical and cultural roles, industrial and ornamental uses, and legal distin…

Orchard: cultivation and uses of fruit- and nut-bearing trees Orchard An orchard is a planned planting of trees or shrubs cultivated for fruit, nuts or other edible produce. This article outlines types, history, management, uses, and distinctions of…

Orchid (Orchidaceae): overview, biology, uses and conservation Orchid Orchids (Orchidaceae) are a diverse family of flowering plants noted for complex flowers, varied growth habits, intricate pollination, and importance in horticulture and vanilla pr…

Orchid (color) Orchid is a bright, floral purple named after orchid flowers. It ranges from grayish-purple to purplish-pink and reddish-purple. First recorded in 1915 and standardized among X11/w…

Oregano (Origanum vulgare) Oregano A perennial herb of the genus Origanum, native to the Mediterranean and Eurasia, widely used in cooking, traditional remedies, and horticulture; known for aromatic leaves and small…

Origanum: the genus of oregano and marjoram — overview, traits, and uses Origanum Origanum is a genus of aromatic herbs in the mint family, native to the Mediterranean and parts of Asia, best known for culinary oregano and sweet marjoram and valued for fragrance…

Ornamental plant: decorative horticulture, uses and cultivation Ornamental plant Plants grown primarily for visual appeal—flowers, foliage, scent, bark or form—used in gardens, containers and interiors. Covers characteristics, cultivation, history and uses in l…

Orto botanico di Pisa — University of Pisa Botanical Garden Orto botanico di Pisa Historic university botanical garden in Pisa, established 1544 under Cosimo I de' Medici and cared for by botanist Luca Ghini; features historic greenhouses, arboretum, herb beds a…

Ovule (plant structure that gives rise to seeds) Ovule An ovule is the structure in seed plants that develops into a seed after fertilization; it contains the megagametophyte (embryo sac), the egg cell, and protective tissues.

Oxalidaceae — the wood-sorrel family of flowering plants Oxalidaceae Oxalidaceae is a plant family of about 900 species, mostly herbaceous, known for sour-tasting leaves (oxalates), compound leaves, five-petaled flowers and tropical-subtropical dist…

Oxalidales — an order of flowering plants Oxalidales Oxalidales is an order of flowering plants of about 1,300 species in six families, including herbs, shrubs and trees such as wood sorrels and the pitcher plant Cephalotus; varied e…

Paleobotany: the study of fossil plants and ancient vegetation Paleobotany Paleobotany (palaeobotany) studies plant fossils and ancient environments. It reconstructs past vegetation, climate and plant evolution using leaves, wood, seeds, pollen, spores an…

Palisade cell Specialized photosynthetic cells in the upper leaf mesophyll that contain many chloroplasts and are adapted for light capture; distinct from spongy mesophyll and common in broad-le…

Palm: hand anatomy, palms (Arecaceae), measures and cultural meanings Palm Comprehensive overview of 'palm' covering the palmar surface of the hand, palms (Arecaceae) as plants, historical units of measure, cultural symbolism, palmistry and common uses.

Palm tree: overview, biology, uses, and cultural importance Palm tree Palms (family Arecaceae) are monocot flowering plants including trees, shrubs and climbers. This article covers their characteristics, distribution, major species, uses, and ecolog…

Palmeral of Elche (Palm Grove of Elche) Palmeral of Elche Historic irrigated date‑palm orchards surrounding Elche, Spain; a Mediterranean cultural landscape notable for its size, traditional irrigation, UNESCO status, and role in local li…

Pandanales (order of tropical monocot flowering plants) Pandanales Pandanales is an order of mostly tropical monocots including palm-like trees, shrubs, lianas and herbs. Members play roles in coastal ecology, traditional uses, and include green a…

Pando (the trembling giant): a clonal aspen colony in Utah Pando (tree) Pando is a single clonal colony of quaking aspen in Utah, notable for its huge connected root system, many identical stems, great age, and current conservation concerns.

Papaver bracteatum (Iranian or Persian poppy) Papaver bracteatum Papaver bracteatum, the Iranian or Persian poppy, is a large scarlet-flowered species cultivated for the alkaloid thebaine used in semi‑synthetic opioid manufacture; it lacks signi…

Papaveraceae — the poppy family: description, traits, and uses Papaveraceae Papaveraceae, the poppy family, comprises mostly herbaceous flowering plants noted for showy flowers, latex or alkaloids, and capsules that release tiny seeds; includes ornamental…