Seed plants

Tostada (tortilla)

Tostada (tortilla): a flat, crispy Mexican corn tortilla, fried or comal-toasted, eaten open-faced with refried beans, protein, cheese, and salsa; prehispanic origin, Aztec name totopochtli, distinct from tacos and chalupas.

Toxicodendron

Toxicodendron, the poison ivy, poison oak, and poison sumac genus of Anacardiaceae, comprises about 33 species disjunctly distributed in East Asia and North America; all contain urushiol, causing allergic dermatitis, and some yield lacquer.

Toxicodendron diversilobum

Toxicodendron diversilobum, western or Pacific poison oak, is a deciduous Anacardiaceae shrub or vine native from British Columbia to northern Mexico whose urushiol oil causes allergic contact dermatitis in 10 to 50 million Americans yearly.

Toxicodendron radicans

Toxicodendron radicans, eastern poison ivy (formerly Rhus radicans), is a North American Anacardiaceae vine or shrub with three leaflets whose urushiol causes allergic contact dermatitis in most people.

Toxicodendron vernix

Toxicodendron vernix (poison sumac, swamp sumac, thunderwood), basionym Rhus vernix, is a wetland Anacardiaceae shrub of eastern North America with 7-13 leaflets on red stalks and urushiol in all parts causing allergic contact dermatitis.

Trachelium

Trachelium (blue throatwort, throatwort) is a small Campanulaceae genus of Macaronesia and the western Mediterranean; Trachelium caeruleum is a violet-blue garden perennial and cut flower with a two-week vase life.

Trachelospermum jasminoides

Trachelospermum jasminoides (络石, teikakazura), star jasmine or confederate jasmine, is an evergreen Apocynaceae liana native from Japan to Vietnam, grown for fragrant white flowers and used in Chinese medicine as caulis trachelospermi.

Trachycarpus fortunei

Trachycarpus fortunei, the Chinese windmill palm or Chusan palm, is a cold-hardy dioecious fan palm native to south-central China and northern Myanmar, widely grown as an ornamental and invasive in southern Switzerland.

Trachyspermum

Trachyspermum (ajwain, Trachyspermum ammi) is a genus of Apiaceae herbs, published by Link in 1821, native from NE Africa to Central Asia; 15 accepted species, polyphyletic, seeds used as spice and medicine.

Tradescantia

Tradescantia (spiderworts), a New World genus of about 90 herbaceous species in Commelinaceae, order Commelinales; includes wandering Jew (T. zebrina), inch plant, and oyster plant (T. spathacea), with Rhoeo, Zebrina, and Setcreasea as synonyms.

Tradescantia ohiensis

Tradescantia ohiensis, Ohio spiderwort, smooth spiderwort, or bluejacket: a clump-forming Commelinaceae perennial native from Ontario to the central and eastern United States, with blue to rose three-petaled one-day flowers, 18 synonyms, and NatureServe rank G5.

Tradescantia pallida

Tradescantia pallida (purple heart, purple queen) is a Mexican trailing Commelinaceae perennial with deep purple leaves and pink morning-opening flowers, mildly irritant sap, easy stem-cutting propagation, and invasive status in parts of South Africa and Italy.

Tradescantia zebrina

Tradescantia zebrina, the zebra plant or inch plant (formerly Zebrina pendula), is a trailing Commelinaceae houseplant native from Mexico to Colombia, with silver-striped purple leaves, easy propagation, and invasive status in Florida, Brazil, and South Africa.

Tragopogon

Tragopogon is a genus of about 130 daisy-family herbs native to temperate Eurasia, the Canary Islands, and North Africa, known for salsify and dandelion-like wind-dispersed fruits.

Tragopogon porrifolius

Tragopogon porrifolius, salsify or oyster plant (Tragopogon sativus), a purple-flowered biennial Asteraceae native from the Canary Islands to the Arabian Peninsula, grown for its oyster-flavored taproot and naturalized widely as a mild weed.

Trapa

Trapa (water caltrop, water chestnut) is a genus of annual floating-leaved aquatic plants in Lythraceae, native to the Old World, with 8 accepted species, starchy edible horned fruits, and invasive populations in North America.

Tree line

Treeline (tree line): the elevation or latitude beyond which climate is too cold for trees, defined as the line connecting uppermost trees >3 m. Set by growing-season temperatures (6.4 °C mean, 94 days), it shifted upslope 0.40 m/yr from 1901–2021, lagging warming by 50+ years.

Trees of India

Trees of India: the country's tree species and tree cover, 827,357 sq km (25.17% of land) per ISFR 2023, in 16 forest type groups from Western Ghats evergreen to Himalayan pine and thorn forests.

Trema

Trema Lour. is a pantropical genus of pioneer trees and shrubs in Cannabaceae, published in 1790, with about 20 species (including Parasponia), 3-veined serrate leaves, and small hard-endocarp drupes.

Triadica

Triadica Lour. (Euphorbiaceae), a three-species Asian tree genus including Chinese tallow (Triadica sebifera), source of vegetable tallow and stillingia oil and invasive in the southeastern United States.

Tribulus cistoides

Tribulus cistoides, Jamaican feverplant or puncture vine, is a prostrate Zygophyllaceae herb native from Cape Verde and Eritrea to Mozambique and the Pacific, with large yellow flowers and spiny burr fruits, used as medicine and food.

Tribulus terrestris

Tribulus terrestris, or puncture vine, is a spiny-fruited herb used in traditional Chinese and Indian medicine and sold as a supplement, though trials show it does not raise testosterone.

Tridactyle

Tridactyle Schltr. is a genus of about 52 accepted African angraecoid orchids (Orchidaceae, Vandeae, Angraecinae), epiphytic monopodial herbs with three-lobed, spurred lips, native to tropical and southern Africa.

Tridax

Tridax (coat buttons, tridax daisy) is a genus of about 25-30 Asteraceae herbs native from Mexico to tropical America, published by Linnaeus in 1753; its type species Tridax procumbens is a pantropical weed used in traditional medicine.

Tridax procumbens

Tridax procumbens (coat buttons, tridax daisy, ghamra) is a creeping Asteraceae herb native to Mexico and tropical America, now a pantropical invasive weed of roadsides and waste ground, used traditionally as a hair tonic and wound remedy.

Trifoliate orange (枳)

Trifoliate orange (枳, karatachi), Citrus trifoliata, formerly Poncirus trifoliata, is a deciduous thorny Chinese citrus relative, the hardiest citrus, used worldwide as a cold-hardy, disease-tolerant semi-dwarfing rootstock and in citrus hybrid breeding.