Tridax

Linnaeus

Sp. Pl. 2: 900. 1753.

,

Gen. Pl. ed. 5, 382. 1754.

Etymology: Etymology recondite perhaps alluding to 3-lobed leaf blades characteristic of original species
Treatment appears in FNA Volume 21. Treatment on page 179. Mentioned on page 176, 177.
 TaxonIllustrator 
FNA21 P28 Tetragonotheca helian.jpegTetragonotheca helianthoides
Tridax procumbens
Galinsoga quadriradiata
Yevonn Wilson-Ramsey
Yevonn Wilson-Ramsey
Yevonn Wilson-Ramsey

Perennials [annuals], 10–40 [–80+] cm. Stems procumbent to ascending. Leaves basal and/or cauline; opposite; petiolate [sessile]; blades deltate, lanceolate, lanceovate, or ovate, often pinnately or palmately lobed, ultimate margins coarsely toothed to subentire, faces glabrate, hirsute, scabrellous, or strigillose. Heads radiate [discoid], borne singly [in ± cymiform arrays]. Involucres cylindric to hemispheric, 4–8 mm diam. Phyllaries persistent, 11–15+ in 2–3+ series (outer usually shorter, more herbaceous, the inner often scarious). Receptacles convex to conic, paleate (paleae ± persistent, lance-linear, scarious, weakly conduplicate, often apically toothed). Ray-florets [0–] 3–8 [–13], pistillate, fertile; corollas pale-yellow [white or purplish]. Disc-florets [20–] 40–80+, bisexual, fertile; corollas yellowish [whitish or purplish], tubes shorter than cylindric or funnelform throats, lobes 5, usually deltate [sometimes rays 0 and corollas of peripheral florets ± bilabiate]. Cypselae obconic to obpyramidal, 3-angled, 4-angled, or 5-angled, densely piloso-sericeous [glabrous, villous]; pappi [sometimes wanting in rays] persistent, of [10–] 20 [–40], plumose [ciliate], setiform scales. x = 10.

Distribution

Introduced; mostly tropical, mostly New World

Discussion

Species ca. 26 (1 in the flora).

Lower Taxa

... more about "Tridax"
not tailed +, rounded +  and obtuse +
darkened +  and pale +
connate +  and distinct +
subequal +
scarious +
usually ovate +  and lanceolate +
usually deltate +  and lanceolate +
spiciform +, racemiform +, paniculiform +  and corymbiform +
indeterminate +  and determinate +
John L. Strother +
Linnaeus +
decurrent +
compound +  and simple +
lobed;ovate;lanceovate;ovate;lanceovate;lanceolate;deltate +
winged;ribbed;winged;ribbed +
tuberculate +  and rugose +
barbellulate +  and barbellate +
yellowish +  and pale-yellow +
piloso-sericeous +
obconic +  and obpyramidal 3-angled 4-angled or 5-angled +
fertile +  and bisexual +
fertile +  and bisexual +
mostly tropical +  and mostly New World +
Etymology recondite +  and perhaps alluding to 3-lobed leaf blades characteristic of original species +
strigillose +, hirsute +  and glabrate +
scabrellous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
cymiform +, corymbiform +, discoid +  and radiate +
indeterminate +
homogamous +  and heterogamous +
each +  and sessile +
0.4 cm4 mm <br />0.004 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
cylindric;hemispheric +
cauline +  and basal +
deltate +
dentate to pinnatifid or palmatifid +  and entire +
2-carpellate +
entire +  and erose +
persistent +
aristate +, laciniate +, fimbriate +  and spatulate +
11 +  and 15 +
unequal +  and subequal +
Sp. Pl. +  and Gen. Pl. ed. +
1753 +  and 1754 +
bearing subulate enations +, hairy +  and bristly +
convex;conic +
powell1965a +
setiform +  and plumose +
exalbuminous +
appendaged +  and truncate +
hirsutulous +  and glabrous +
papillate +
Compositae +
Asteraceae (tribe Heliantheae) subtribe Galinsoginae +
cylindric +
coarsely toothed +  and subentire +
40 cm400 mm <br />0.4 m <br /> (80 cm800 mm <br />0.8 m <br />) +
10 cm100 mm <br />0.1 m <br /> (40 cm400 mm <br />0.4 m <br />) +
150 cm1,500 mm <br />1.5 m <br /> (300 cm3,000 mm <br />3 m <br />) +
shrub +  and subshrub +