Tridax

Annual or perennial herbs. Leaves opposite. Capitula solitary on long peduncles, radiate, heterogamous. Ray florets female, fertile; disk bisexual and fertile. Involucre ± hemispheric. Phyllaries in 2 series, the outer shorter than or equal to the inner. Rays present, 3-lobed or dentate; disk florets cylindric, 5-lobed. Receptacular scales linear, ± keeled. Achenes silky-villous. Pappus of numerous densely plumose bristles.

Tridax is a genus of flowering plants in the family Asteraceae.

Tridax is native primarily to the tropical regions of North and South America. Tridax procumbens has become naturalized in the southern United States and is considered a noxious weed in some places.

Species Tridax angustifolia Spruce ex Benth. & Hook.f. - Ecuador, Peru Tridax balbisioides (Kunth) A.Gray - Guanajuato Tridax bicolor A.Gray - Chihuahua Tridax bilabiata A.M.Powell - Guerrero Tridax boliviensis (Wedd.) R.E.Fr. - Bolivia Tridax brachylepis Hemsl. - Oaxaca Tridax cajamarcensis H.Rob. - Peru Tridax candidissima A.Gray - San Luis Potosí Tridax coronopifolia (Kunth) Hemsl. - widespread from Tamaulipas to Chiapas Tridax dubia Rose - Colima Tridax erecta A.Gray Tridax hintonii (B.L.Turner & A.M.Powell) D.J.Keil, Luckow & Pinkava - Michoacán Tridax hintoniorum B.L.Turner - Nuevo León Tridax luisana Brandegee - Puebla, Oaxaca Tridax mexicana A.M.Powell - Guerrero, Oaxaca, Jalisco, México State, Veracruz, Nayarit, Michoacán Tridax moorei B.L.Rob. - Hidalgo Tridax oaxacana B.L.Turner - Oaxaca Tridax obovata Turcz. - Oaxaca Tridax oligantha C.E.Anderson & Beaman Tridax palmeri A.Gray - San Luis Potosí Tridax platyphylla B.L.Rob. - Jalisco Tridax procumbens (L.) L. - Veracruz; widespread invasive Tridax purpurea S.F.Blake - Guatemala, Chiapas Tridax rosea Sch.Bip. ex B.L.Rob. & Greenm. - Hidalgo, D.F. Tridax tambensis Hieron. - Peru, Ecuador Tridax tenuifolia Rose - Chihuahua Tridax trilobata (Cav.) Hemsl. - Michoacán, México State Tridax venezuelensis Aristeg. & Cuatrec. - Venezuela Tridax yecorana B.L.Turner - eastern Sonora in Sierra Madre Occidental formerly included

see Calea Layia Sabazia

Tridax accedens - Calea verticillata Tridax ehrenbergii - Sabazia sarmentosa Tridax gaillardioides - Layia gaillardioides Tridax verticillata - Calea verticillata