Plants

Tuber (plant organ): storage stems and related structures Tuber A tuber is a thickened plant organ—most often an underground stem—used to store nutrients and bear buds for vegetative reproduction; common examples include the potato and some aer…

Tulip (Tulipa): overview, description, history and cultivation Tulip Tulips (genus Tulipa) are bulbous spring-flowering plants prized for their colorful, cup-shaped blooms. This article explains their appearance, native range, history, garden uses a…

Tulipa clusiana (lady tulip) — description, habitat and cultivation Tulipa clusiana Tulipa clusiana, the lady tulip, is a slender wild tulip from parts of Central and Southwest Asia. This entry summarizes its appearance, native range, cultivation, history and dist…

Tulipa gesneriana — the garden tulip Tulipa gesneriana Tulipa gesneriana, commonly called the garden tulip, is a bulbous spring-flowering plant cultivated worldwide for its large showy blooms and many garden cultivars.

Tulipa sylvestris (wild tulip) Tulipa sylvestris Tulipa sylvestris is a scented, low-growing wild tulip that naturalizes in meadows and woodlands. Native to parts of Europe, North Africa and western Asia, it is valued for its but…

Tumbleweed: wind-driven seed and spore dispersal in arid landscapes Tumbleweed A tumbleweed is a detached plant or reproductive structure that rolls in the wind to disperse seeds or spores. Common in open, dry regions, it is an important ecological and cultur…

Tutsan (Hypericum androsaemum) — shrubby St John’s-wort Tutsan Tutsan (Hypericum androsaemum) is a woody Eurasian shrub with bright yellow flowers and red-to-black berries. Valued ornamentally and in traditional herbal use, it is closely relat…

Tutu (Coriaria): New Zealand shrubs and their poisonous honey risk Tutu (plant) Tutu is the Māori name for New Zealand species of Coriaria, shrubs and small trees that contain the neurotoxin tutin. They are notable for poisonous fruit, traditional uses, and oc…

Twig: small woody branch — structure, identification, uses, and significance Twig A twig is a small, thin woody branch. This article describes twig anatomy, winter identification features, ecological roles, practical uses, and how twigs differ from shoots and la…

Typha (cattails, bulrushes): wetland plants, description, uses, and ecology Typha Typha is a genus of tall, water-loving plants (cattails or bulrushes) with distinctive brown flower spikes; important in wetlands for habitat, traditional uses, and water filtratio…

Ugli fruit (Jamaican tangelo) Ugli fruit A citrus hybrid originally identified in Jamaica, the ugli fruit is prized for its sweet-tart flesh despite a rough, wrinkled rind; used fresh, juiced, and in cooking and preserves…

Ugni (genus of flowering plants) Ugni Ugni is a small genus of evergreen shrubs in the myrtle family (Myrtaceae), best known for the edible Chilean guava. Native to western parts of the Americas, its berries and orname…

Ulmaceae: the elm and zelkova family of flowering trees Ulmaceae Ulmaceae is a small family of deciduous and occasionally evergreen trees and shrubs, best known for elms (Ulmus) and zelkovas (Zelkova). They are temperate, wind- or insect-pollina…

Ulmus wallichiana (Himalayan or Kashmir Elm) Ulmus wallichiana Ulmus wallichiana, the Himalayan or Kashmir elm, is a deciduous tree native to the western Himalaya, recognized for its timber, landscape value, and role in elm-breeding and local…

Umbrella tree (common name for several plant species) Umbrella tree Umbrella tree is a vernacular name applied to unrelated plants whose leaves or crown resemble an open umbrella; commonly used for Schefflera species, Cyperus papyrus relatives, and…

United States Botanic Garden The national botanical garden on the National Mall in Washington, D.C., dedicated to plant conservation, exhibits, research, and public education since 1920.

United States National Arboretum A public arboretum in Washington, D.C., housing extensive tree and plant collections, research programs, the National Bonsai & Penjing Museum, and the historic National Capitol Col…

Urticaceae — the nettle family Urticaceae A concise overview of Urticaceae: plant traits, taxonomy, ecology, notable genera and human uses, including stinging hairs, fiber plants, ornamentals and their place in modern clas…

Vaccinium: the berry-producing shrub genus Vaccinium Vaccinium is a diverse genus of shrubs in the Ericaceae family, including blueberries, cranberries, bilberries and huckleberries; species occur mainly in temperate zones and are im…

Vaccinium vitis-idaea (lingonberry) — small evergreen berry shrub Vaccinium vitis-idaea Vaccinium vitis-idaea, commonly called lingonberry or cowberry, is a low evergreen shrub of the heath family producing tart red edible berries used in northern cuisines, preserves…

Valencia orange: a sweet orange cultivar prized for juice Valencia orange Valencia is a sweet orange cultivar developed in California, valued for high juice content and a late-season harvest (spring to early summer); historically important in the U.S. ci…

Valonia ventricosa — bubble algae, a giant single-celled green alga Valonia ventricosa Valonia ventricosa is a marine green alga known as bubble algae or sailors’ eyeballs; notable as one of the largest single cells, found in tropical and subtropical seas and studied…

Vanda (orchid): description, distribution, cultivation and significance Vanda Vanda is a genus of mainly epiphytic orchids prized for showy, long‑lasting flowers. This article summarizes appearance, natural range, cultivation, propagation and conservation co…

Vanilla: the orchid-derived spice and its uses Vanilla Vanilla is a spice and aromatic flavoring obtained from orchids of the genus Vanilla. The pods undergo curing to develop aroma; both natural extract and synthetic vanillin are used…

Variety (botany) A botanical variety is an infraspecific rank below species and subspecies used to name stable, naturally occurring plant differences with consistent morphological traits.

Vascular cambium A vascular cambium is a lateral meristem that produces secondary xylem and phloem, allowing stems and roots to thicken and form wood and inner bark in many seed plants.

Vascular plant (Tracheophyte): structure, life cycle and significance Vascular plant Overview of vascular plants (tracheophytes): their conducting tissues (xylem, phloem), organs, major groups, life cycle dominance of the sporophyte, evolution, and ecological and e…

Vascular tissue (plants) Vascular tissue Specialized plant tissue that conducts water, minerals and sugars; composed mainly of xylem and phloem and organized into the vascular tissue system of vascular plants.

Vegetation: plant cover, communities, and ecological roles Vegetation An overview of vegetation as the assemblage of plant cover and communities: definition, components, scales, measurement, ecological functions, human impacts, classification and man…

Vegetative reproduction: asexual plant propagation and its methods Vegetative reproduction Vegetative reproduction is a form of asexual plant propagation in which new individuals arise from somatic parts. Methods include runners, bulbs, tubers, cuttings and tissue cultur…

Venus flytrap (Dionaea muscipula) Venus flytrap A carnivorous flowering plant native to the coastal plains of the southeastern United States, noted for its rapid snap-traps that capture insects to obtain nutrients in nutrient-po…

Verbena (vervain): description, characteristics, history and uses Verbena Verbena (vervain) is a genus of flowering plants in the Verbenaceae family. Species are grown as ornamentals, used in traditional remedies, and valued for attracting pollinators; s…

Verbenaceae — the verbena family Verbenaceae Verbenaceae is a family of flowering plants in Lamiales, including shrubs, trees and herbs. Members have opposite leaves, tubular flowers and variable fruit; many are ornamental or…

Vernonia gigantea (Tall ironweed): description, habitat, and uses Vernonia gigantea Vernonia gigantea, or tall ironweed, is a perennial North American wildflower in the aster family known for late-summer purple flowerheads, pollinator value, and presence in moist…

Vessel element (plant water-conducting cell) Vessel element A vessel element is a specialized cell in the xylem of flowering plants that forms part of vessels used for long-distance water transport, differing from tracheids of many gymnospe…

Vinca (Periwinkle): a temperate groundcover genus Vinca Vinca is a small genus of evergreen, trailing subshrubs in the Apocynaceae family, native to Europe, northwest Africa and southwest Asia, widely used as ornamental groundcover and…

Vine (climbing plant): growth habits, types, ecology and uses Vine Vines are plants with a climbing or trailing habit that use stems, tendrils, roots or runners to reach light. This article summarizes their structure, types, ecology, cultivation a…

Viola sororia (common blue violet) Viola sororia Viola sororia is a perennial North American violet with heart-shaped leaves and purple flowers; notable for cleistogamous blooms, moth and butterfly associations, edible parts, and…

Violaceae: the violet family of flowering plants Violaceae Violaceae is a cosmopolitan family of mostly herbaceous plants including violets and pansies; notable for distinctive zygomorphic flowers, cleistogamy, ornamental and ecological im…

Violet — the color and the flower Violet Violet: a spectral color at the blue end of visible light and the common name for flowering plants in the genus Viola, known for small purple blossoms and cultural symbolism.

Violet (Viola): genus of flowering plants, uses and cultivation Violet (plant) Violets (genus Viola) are small herbaceous plants with heart-shaped leaves and zygomorphic flowers. Widely grown as ornamentals and used in cuisine, perfumery and symbolism, they i…

Viridiplantae: the green plants (green algae and land plants) Viridiplantae Viridiplantae is the clade of green algae and land plants characterized by green chlorophyll, primary plastids, cellulose cell walls and starch storage; essential primary producers…

Vitaceae — the grape family of woody vines and lianas Vitaceae Vitaceae is a family of mostly woody climbing flowering plants that includes grapes and ornamental creepers; notable for economic importance, specialized climbing structures, and a…

Vitis (grapevines) Vitis Vitis is a genus of about 60 species of woody, climbing plants in the Vitaceae family. It supplies grapes for fresh use, drying and wine, and includes both wild relatives and widel…

Wahlenbergia: a widespread genus of bellflowers Wahlenbergia Wahlenbergia is a genus of herbaceous bellflowers (Campanulaceae) with about 150–270 species, native mainly to Africa and Australasia and notable for small blue bell-shaped flowers…

Walnut (Juglans) — trees, wood, and edible nuts Walnut Walnut (genus Juglans) are temperate trees grown for hardwood timber and edible nuts. This article covers their appearance, range, uses (wood, food, oil), ecological traits and cul…

Water chestnut (Chinese water chestnut, Eleocharis dulcis) Water chestnut An overview of the Chinese water chestnut (Eleocharis dulcis): its botany, edible corms, cultivation in flooded fields, culinary uses, storage and how it differs from other plants…

Water hyacinth (Eichhornia): biology, impacts and uses Water hyacinth Floating aquatic plants in the genus Eichhornia known for rapid growth, invasive mats, and varied uses from wastewater treatment to crafts; native to South America and widely intro…