Asteraceae

Tridax L.

First published in Sp. Pl.: 900 (1753)
This genus is accepted
The native range of this genus is Mexico to Tropical America.

Descriptions

M. Thulin. Flora of Somalia, Vol. 1–4 [updated 2008] https://plants.jstor.org/collection/FLOS

Distribution
Some 30 species in tropical America, one a pantropical weed.
Morphology General Habit
Annual or perennial herbs
Morphology Leaves
Leaves opposite, rarely alternate near inflorescence
Morphology Reproductive morphology Inflorescences Capitulum
Capitula solitary or in panicles, discoid or radiate, heterogamous; phyllaries 1–5‑seriate
Morphology Reproductive morphology Flowers Receptacle
Receptacle paleate
Morphology Reproductive morphology Flowers Florets
Ray florets pistillate, fertile, ± 2-lipped, paleae partly enclosing achene
Morphology Reproductive morphology Flowers Disc
Disk florets bisexual, fertile
Morphology Reproductive morphology Flowers Corolla
Corolla cylindric, 5‑lobed
Morphology Reproductive morphology Flowers Androecium Stamens Anthers
Anthers sagittate at base
Morphology Reproductive morphology Flowers Gynoecium Style
Style bifurcate
Morphology Reproductive morphology Fruits
Achenes black, often recurved near edge of heads
Morphology Reproductive morphology Seeds Pappus
Pappus of scales and/or slender bristles, rarely absent.
[FSOM]

Compositae, H. Beentje, C. Jeffrey & D.J.N. Hind. Flora of Tropical East Africa. 2005

Morphology General Habit
Annual or perennial herbs
Morphology Leaves
Leaves opposite (or alternate in non-weedy species)
Morphology Reproductive morphology Inflorescences Capitulum
Capitula terminal, solitary on long stalks (or paniculate in non-weedy species), radiate or discoid; involucre 1–5-seriate; paleae linear and keeled
Morphology Reproductive morphology Flowers Florets
Ray florets female; disc florets hermaphrodite, cylindric; anthers with sagittate base and terminal appendage; style arms linear, pubescent, style-base with globose swelling
Morphology Reproductive morphology Fruits
Achenes with pappus of many plumose bristles.
[FTEA]

George R. Proctor (2012). Flora of the Cayman Isands (Second Edition). Royal Botanic Gardens, Kew

Morphology General Habit
Perennial herbs with decumbent stems; leaves opposite and toothed or incised
Morphology Reproductive morphology Flowers
Heads radiate, solitary on long terminal or axillary peduncles; involucre ovoid or hemispheric, its bracts subequal in 2–3 series; receptacle flat or convex, bearing chaffy scales subtending the disc-florets
Ray
Ray-florets pistillate, with 3-lobed or -toothed ligules
Disc
Disc- florets perfect and fertile, tubular and 5-lobed; anthers auricled or sagittate at the base; style-arms subulate-appendaged
Morphology Reproductive morphology Fruits
Achenes compressed, silky-hairy; pappus of many plumose bristles or scales.
Distribution
A tropical American genus of more than 25 species.
[Cayman]

Sources

  • Flora of Somalia

    • Flora of Somalia
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Flora of Tropical East Africa

    • Flora of Tropical East Africa
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Flora of the Cayman Islands

    • Flora of the Cayman Islands
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0

  • World Checklist of Vascular plants (WCVP)

    • The International Plant Names Index and World Checklist of Vascular Plants 2024. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0