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|Jepson eFlora: Taxon page
Key to families | Table of families and genera
Index to accepted names and synonyms:
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|Family: Asteraceae (Compositae)||View Description||Dichotomous Key|
|Genus:||View Description||Dichotomous Key|
|Species:||View Description||Dichotomous Key|
Habit: Annual, coarse, 10--200+ cm. Stem: erect, branched; nodal spines present or 0. Leaf: generally alternate (proximal 2--6 occasionally opposite), petioled or distal sessile, linear to nearly round, often +- palmately or pinnately lobed, ultimate margins entire or +- toothed, faces minutely coarse-hairy or +- strigose, generally gland-dotted. Inflorescence: heads unisexual, 1, axillary or in raceme- to spike-like clusters, pistillate generally proximal, staminate generally distal. Staminate Head: 3--5 mm diam; involucre +- saucer-shaped, phyllaries 6--16+ in 1--2+ series, free, +- 1 mm; receptacle conic to columnar, paleae spoon-shaped to wedge-shaped or linear, membranous, distally +- soft-hairy or minutely coarse-hairy. Pistillate Head: 2--5+ mm diam at flower, 6--20+ mm diam in fruit, +- ellipsoid; bracts 30--75+ in 6--12+ series, all proximally fused or outer 5--8 free, tips free, mostly +- hooked except distal 1--3 (generally longer, stouter), together becoming a hard, prickly bur. Staminate Flower: 20--150+; corolla +- funnel-shaped, +- white, lobes 4--5, erect or reflexed, filaments fused, anthers free or weakly fused; style tip undivided. Pistillate Flower: 2: corolla 0, style tips linear, exserted. Fruit: fusiform, black, enclosed in obovoid to ellipsoid, 2-chambered bur; pappus 0.
Species In Genus: 2--3 species: +- worldwide; native to New World. Etymology: (Greek: yellow, from fruit-extract dye)
eFlora Treatment Author: Bruce G. Baldwin, adapted from Strother (2006)
Jepson Online Interchange
Key to XanthiumPrevious taxon: Xanthisma spinulosum var. gooddingii
Next taxon: Xanthium spinosum
Citation for this treatment: Bruce G. Baldwin, adapted from Strother (2006) 2016. Xanthium, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=661, accessed on August 31, 2016.
Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on August 31, 2016.