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See list of 4 species in this genus

Reference: Lamont (2006).

  • 1a. Capitula with (8–) 9–22 flowers; capitulescence or its divisions flat-topped [Fig. 411]; 
stems typically green with anthocyanic spots or streaks
  • 1b. Capitula with (4–) 5–9 (–10) flowers; capitulescence or its divisions slightly to strongly convex [Fig. 410]; stems spotted with anthocyanin or anthocyanic only in bands at the nodes or uniformly anthocyanic throughout the stem
    • 2a. Leaf blades triple-veined, with the lowest pair of lateral veins more conspicuous and more prolonged than the other lateral veins, abruptly contracted to the petiole; stems spotted or streaked with anthocyanin
    • 2b. Leaf blades pinnately veined or gradually tapered to the petiole or both; stems usually with anthocynin concentrated in nodal bands or uniformly distributed throughout the stem
      • 3a. Stems usually with anthocyanin concentrated in nodal bands 1–2 cm long, not or only scarcely glaucous, solid or developing a slender central cavity near the base; plants typically occurring in upland, deciduous woodlands and in open, well-drained habitats
      • 3b. Stems usually anthocyanic throughout (though often green in deep shade and sometimes spotted when young), prominently glaucous, developing a large central cavity; plants typically occurring in wetlands, riparian communities, and other low, 
hydric habitats

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