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1 Plant a shrub or small tree, 3-6 (-10) m tall, definitely woody; stem armed throughout with prickles, those on the stem stout, broad-based, and distributed to the summit of the stem; leaves usually armed with prickles on the axes and the main veins; [section Dimorphanthus]
..2 Inflorescence 3-6 dm long, often broader than long, the main axis absent or to 15 cm long; main lateral veins of the leaflets running all the way to the teeth; petiolules 0-1 (-6) mm long; dry fruit 3.0-3.5 mm long; corolla white to off-white; leaves 2-pinnate, basal pair of pinnae subtended by pair of accessory leaflets; drupes 4-4.5 mm in diameter; [exotic spreading southward from ne. United States]
..2 Inflorescence 4-12 dm long, usually longer than broad, with a well-developed central axis 30-40 cm long; main lateral veins of the leaflets branching repeatedly and getting smaller before reaching the marginal teeth as small branching veinlets; petiolules 1-7 mm long; dry fruit 4.0-5.0 mm long; corolla creamy or buttery yellow; leaves 2-3-pinnate, basal pair of pinnae usually subtended by pair of accessory pinnae with 3--5 leaflets, sometimes by pair of accessory leaflets; drupes 5-8 mm in diameter; [widespread native]
1 Plant an acaulescent herb or stout, suffruticose herb or slightly woody shrub, not at all to somewhat woody at the base; stem unarmed (or in A. hispida bristly with thin prickles on the lower stem only); leaves unarmed.
....3 Plant an acaulescent herb, the solitary leaf and scapose inflorescence arising from a subterranean rhizome; inflorescence a raceme of (2-) 3 (-7) umbels; [section Nanae]
....3 Plant a caulescent herb, the leaves several and alternate, the inflorescence terminal on the leafy stem; inflorescence a raceme or panicle of (2-) 5-many umbels.
......4 Stem bristly toward its base; inflorescence a raceme or weak panicle of (2-) 5-25 umbels; [section Dimorphanthus]