Xanthium

Linnaeus

Sp. Pl. 2: 987. 1753.

,

Gen. Pl. ed. 5, 424. 1754.

Common names: Lampourde
Etymology: Greek xanthos, yellow, evidently alluding to an ancient name for a plant that produced a yellow dye
Treatment appears in FNA Volume 21. Treatment on page 19. Mentioned on page 9.

Annuals (coarse), 10–200+ cm. Stems erect, branched. Leaves cauline; mostly alternate (proximal 2–6 sometimes opposite); petiolate; blades lanceolate, linear, ovate, rounded-deltate, or suborbiculate, often ± palmately or pinnately lobed, ultimate margins entire or ± toothed, faces hirtellous or ± strigose, usually glanddotted as well. Heads discoid, either pistillate (proximal) or functionally staminate (distal), in racemiform to spiciform arrays or borne singly (in axils). Pistillate heads: involucres ± ellipsoid, 2–5+ mm diam. at anthesis (6–20+ mm diam. at maturity); phyllaries 30–75+ in 6–12+ series, outer 5–8 distinct, the rest (sometimes interpreted as paleae) proximally connate, their distinct tips mostly ± hooked (the distal 1–3 usually longer, stouter, and not hooked), the whole becoming a hard, prickly perigynium (a bur); florets 2, corollas 0. Staminate heads: involucres ± saucer-shaped, 3–5 mm diam.; phyllaries 6–16+ in 1–2+ series, distinct to bases; receptacles conic to columnar; paleae spatulate to cuneiform or linear, membranous, distally ± villous or hirtellous; florets 20–50+, corollas whitish, ± funnelform, lobes 5, erect or reflexed (filaments connate, anthers distinct or weakly coherent). Cypselae (black) ± fusiform, enclosed in obovoid to ellipsoid, hard, prickly, 2-chambered burs; pappi 0. x = 18.

Distribution

New World, nearly worldwide

Discussion

Species 2–3 (2 in the flora).

Selected References

None.

Key

1 Nodal spines 0; leaf blades suborbiculate to ± pentagonal or deltate Xanthium strumarium
1 Nodal spines (1–)3-lobed, 15–30+ mm; leaf blades ± lanceolate to ovate or lance-linear Xanthium spinosum
... more about "Xanthium"
not tailed +, rounded +  and obtuse +
connate +  and distinct +
subequal +
scarious +
usually ovate +  and lanceolate +
usually deltate +  and lanceolate +
spiciform +, racemiform +, paniculiform +, glomerate +  and corymbiform +
indeterminate +  and determinate +
John L. Strother +
Linnaeus +
decurrent +
compound +  and simple +
lobed;suborbiculate;rounded-deltate;suborbiculate;rounded-deltate;ovate;linear;lanceolate +
winged;ribbed;winged;ribbed +
tuberculate +  and rugose +
barbellulate +  and barbellate +
2-chambered +  and prickly +
Lampourde +
villous +, strigillose +, hispidulous +, glabrous +  and warty +
scabrellous +  and tuberculate +
fertile +  and bisexual +
New World +  and nearly worldwide +
Greek xanthos, yellow, evidently alluding to an ancient name for a plant that produced a yellow dye +
strigose +  and hirtellous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
staminate +, pistillate +, racemiform +  and spiciform +
indeterminate +
homogamous +  and heterogamous +
each +  and sessile +
membranous +  and scarious +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
saucer--shaped;ellipsoid +
conspicuous +
reflexed;erect +
deltate +
dentate to pinnatifid or palmatifid +  and entire +
connate +  and distinct +
2-carpellate +
hirtellous +  and villous +
spatulate;cuneiform or linear +
membranous +
persistent +
6 +  and 16 +
unequal +  and subequal +
Sp. Pl. +  and Gen. Pl. ed. +
1753 +  and 1754 +
bearing subulate enations +, hairy +  and bristly +
conic;columnar +
exalbuminous +
appendaged +  and truncate +
hirsutulous +  and glabrous +
papillate +
Undefined (tribe Undefined) subtribe Ambrosieae +  and Undefined (tribe Undefined) subtribe Iveae +
Xanthium +
Asteraceae (tribe Heliantheae) subtribe Ambrosiinae +
campanulate +  and cylindric +
distinct +
hooked +
toothed +  and entire +
10 cm100 mm <br />0.1 m <br /> (200 cm2,000 mm <br />2 m <br />) +
shrub +  and subshrub +