What’s a dichotomous key? Get HelpSee list of 4 species in this genus
- Group 1Lycophytes, Monilophytes
- Group 2Gymnosperms
- Group 3Monocots
- Group 4Woody angiosperms with opposite or whorled leaves
- Group 5Woody angiosperms with alternate leaves
- Group 6Herbaceous angiosperms with inferior ovaries
- Group 7Herbaceous angiosperms with superior ovaries and zygomorphic flowers
- Group 8Herbaceous angiosperms with superior ovaries, actinomorphic flowers, and 2 or more distinct carpels
- Group 9Herbaceous angiosperms with superior ovaries, actinomorphic flowers, connate petals, and a solitary carpel or 2 or more connate carpels
- Group 10Herbaceous angiosperms with superior ovaries, actinomorphic flowers, distinct petals or the petals lacking, and 2 or more connate carpels
Reference: Strother (2006a).
1a. Staminate capitula sessile or subsessile, in a solitary, spike-like capitulescence; staminate involucres prolonged into a long, retrorse, lanceolate to triangular-ovate, hooded, bristly tooth; leaf blades lanceolate to narrow-lanceolate, entire to lobed, when lobed with 1 or 2 pairs of pinnately arranged lobes that are confined to the base of the blade
1b. Staminate capitula peduncled, borne in 1 or more raceme-like capitulescences; staminate involucres without a prolonged, retrorse lobe, actinomorphic or nearly so; leaf blades lanceolate or elliptic to ovate or triangular, 1- or 2-times pinnately lobed, or entire to palmately lobed in A. trifida, but that species with some broad-lanceolate to ovate, unlobed blades on the plant
2b. Plants annual or perennial, 0.2–1 (–2.5) m high; leaves usually opposite below and alternate above, once- or twice-pinnatifid; receptacle with chaff; staminate involucre inconspicuously nerved (i.e., the faint nerves of ± equal prominence in all directions); carpellate involucre mostly 3–5 mm long in fruit
Show photos of: Each photo represents one species in this genus.