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See list of 5 species in this genus
  • 1a. Plants scapose, both the leafless peduncle arising from near ground level and the single leaf arising from a very short, woody stem at the surface of the ground
  • 1b. Plants with evident, leafy stems, the peduncles arising from well above the surface of 
the ground
    • 2a. Plants shrubs or small trees, up to 10 m tall, armed with stout prickles; styles distinct (sometimes connate to near the middle in A. elata)
      • 3a. Leafules (or leafulets on tripinnately compound leaves) ± glabrous abaxially, with veins anastomosing before reaching the marginal teeth, with petiolules longer than 2 mm; branchlets light brown
      • 3b. Leafules (or leafulets on tripinnately compound leaves) pubescent abaxially, with veins essentially running into the marginal teeth, subsessile; branchlets light gray
    • 2b. Plants herbaceous, up to 2 m tall, unarmed or armed with slender bristles near the base of the plant; styles connate about half their length
      • 4a. Inflorescence composed of a few to several umbels in a cluster resembling a corymb; stems armed near the base with slender bristles; plants commonly of dry, sandy, and/or sterile soils; ultimate leaf segments rounded to cuneate at the base
      • 4b. Inflorescence composed of numerous umbels in a cluster resembling a panicle; stems unarmed; plants of rich, mesic soils; ultimate leaf segments cordate at the base

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 Show photos of:   Each photo represents one species in this genus.