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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 to small tree; monoecious. Leaf: simple, opposite or alternate, generally petioled, entire to 1--4-pinnately lobed or divided, distal-most often reduced, bract-like. Inflorescence: staminate heads and pistillate heads together in distal leaf axils or in terminal, spike-like clusters, or staminate heads in spike- or raceme-like clusters distal to pistillate heads; staminate involucre +- cup-shaped, phyllaries in 1 series, +- fused, receptacle flat or rounded, paleate; pistillate phyllaries 0 or few, in 1 series, free, +- thin, receptacle paleate, palea bases fused, becoming a hard bur with each pistillate flower in a separate chamber, tips (occasionally not evident in flower heads) becoming hard knobs, spines, or scarious wings. Staminate Flower: 3--many; corolla translucent to yellow or red-purple; filaments fused, anthers free; style unbranched, ovary vestigial, pappus 0. Pistillate Flower: 1--5; corolla 0; style branches elongated. Fruit: inside bur with beak(s) surrounding style(s); pappus 0.
Species In Genus: 45--50 species: native to America, especially southwestern United States, northern Mexico. Etymology: (Greek: early name for aromatic plants; mythic food of the gods) Note: Wind-blown pollen often allergenic.
Unabridged Note: Spines of bur derived from paleas, not phyllaries.
eFlora Treatment Author: David J. Keil
Jepson Online Interchange
Key to AmbrosiaPrevious taxon: Amblyopappus pusillus
Next taxon: Ambrosia acanthicarpa
Citation for this treatment: David J. Keil 2016. Ambrosia, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=306, accessed on February 12, 2016.
Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on February 12, 2016.