Tetragonotheca

Linnaeus

Sp. Pl. 2: 903. 1753.

,

Gen. Pl. ed. 5, 384. 1754.

Etymology: Greek tetra, four, gonio, angle, and theca, container, alluding to quadrangular involucres
Treatment appears in FNA Volume 21. Treatment on page 178. Mentioned on page 176.
 TaxonIllustrator 
FNA21 P28 Tetragonotheca helian.jpegTetragonotheca helianthoides
Tridax procumbens
Galinsoga quadriradiata
Yevonn Wilson-Ramsey
Yevonn Wilson-Ramsey
Yevonn Wilson-Ramsey

Perennials, mostly 30–120 cm. Stems erect. Leaves basal and/or cauline; mostly opposite; petiolate, subpetiolate, or sessile (bases sometimes connate-perfoliate); blades lanceolate, ovate, rhombic, or rounded-deltate, sometimes pinnatifid, ultimate margins usually toothed, faces glabrate, sparsely hispidulous, or puberulent, glanddotted. Heads radiate, borne singly or in loose, corymbiform arrays. Involucres obpyramidal to hemispheric, 12–25+ mm diam. Phyllaries persistent, 10–25+ in ± 2 series (outer 4 broadly lanceolate, foliaceous, the inner ovate to lanceolate, smaller, more scarious, each subtending a ray-floret). Receptacles conic, paleate (paleae persistent, lanceolate to lanceovate, flat or weakly conduplicate, apices acute). Ray-florets 6–21+, pistillate, fertile; corollas yellow (often with reddish nerves). Disc-florets 25–150+, bisexual, fertile; corollas yellow, tubes (basally dilated) much shorter than ampliate, cylindric throats, lobes 5, deltate. Cypselae ± ovoid or plumply 4-angled or 5-angled, finely 32–40-ribbed, sparsely strigose or glabrous; pappi 0, or of 1–10+ subulate to acerose scales (to 0.5 mm), or of 16–30, ± spatulate scales (0.5–2 mm). x = 17.

Distribution

s United States, n Mexico

Discussion

Species 4 (4 in the flora).

Key

1 Pappi of 16–30, ± obovate to spatulate scales 0.5–2 mm > 2
1 Pappi 0, or of 1–10+ subulate to acerose scales to 0.5 mm > 3
2 Leaves mostly cauline (distal connate-perfoliate); ray florets 12–13, laminae 8–18 mm Tetragonotheca ludoviciana
2 Leaves mostly basal (cauline much smaller, none connate-perfoliate); ray florets 16–21+, laminae 20–30+ mm Tetragonotheca repanda
3 Stems sparsely tomentulose or glabrous (nodes usually auriculate-appendaged); ray laminae 10–18 mm; cypselae ± quadrate, 2.5–4 mm Tetragonotheca texana
3 Stems patently to retrorsely ± villous; ray laminae 20–40+ mm; cypselae ± ovoid, 4–6 mm Tetragonotheca helianthoides
... more about "Tetragonotheca"
not tailed +, rounded +  and obtuse +
darkened +  and pale +
connate +  and distinct +
subequal +
scarious +
usually ovate +  and lanceolate +
usually deltate +  and lanceolate +
indeterminate +  and determinate +
John L. Strother +
Linnaeus +
decurrent +
compound +  and simple +
pinnatifid;rounded-deltate;rhombic;rounded-deltate;rhombic;ovate;lanceolate +
winged;ribbed;winged;ribbed +
tuberculate +  and rugose +
barbellulate +  and barbellate +
glabrous +  and strigose +
5-angled +, 4-angled +  and ovoid +
fertile +  and bisexual +
fertile +  and bisexual +
s United States +  and n Mexico +
Greek tetra, four, gonio, angle, and theca, container, alluding to quadrangular involucres +
puberulent +, hispidulous +  and glabrate +
scabrellous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
cymiform +, corymbiform +, discoid +  and radiate +
in loose , corymbiform arrays +  and singly +
indeterminate +
homogamous +  and heterogamous +
each +  and sessile +
1.2 cm12 mm <br />0.012 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
obpyramidal;hemispheric +
sessile +, subpetiolate +  and petiolate +
cauline +  and basal +
deltate +
dentate to pinnatifid or palmatifid +  and entire +
2-carpellate +
entire +  and erose +
persistent +
1 +  and 10 +
subulate +  and acerose +
10 +  and 25 +
unequal +  and subequal +
Sp. Pl. +  and Gen. Pl. ed. +
1753 +  and 1754 +
bearing subulate enations +, hairy +  and bristly +
turner1980a +
16 +  and 30 +
spatulate +
exalbuminous +
appendaged +  and truncate +
hirsutulous +  and glabrous +
papillate +
Compositae +
Tetragonotheca +
Asteraceae (tribe Heliantheae) subtribe Galinsoginae +
cylindric +
ampliate +
30 cm300 mm <br />0.3 m <br /> (120 cm1,200 mm <br />1.2 m <br />) +
150 cm1,500 mm <br />1.5 m <br /> (300 cm3,000 mm <br />3 m <br />) +
shrub +  and subshrub +