1A.	Inflorescences terminal to stems of current year, exerted from foliage, arranged in pseudoracemes or umbels	C. houstoniana ssp. houstoniana
1B.	Inflorescences lateral, axillar or from efoliate brachyblasts	2
2A.	Leaves with 1 pair of pinnae	3
2B.	Leaves with 2 or more pairs of pinnae	4
3A.	Each pinnae exactly trifoliolate	C. tergemina ssp. emarginata
3B.	Each pinnae with 3 or more pairs of pinnae	5
4A.	Peduncles 1–5 mm long; petals pubescent	C. conferta
4B.	Peduncles 10–20 mm long; petals glabrous or nearly so	C. isleyi
5A.	Capitula with 1–3 flowers, typically 2; leaves spirally arranged on stems; leaves with 2–3 pairs of pinnae, leaflets 7–10 pairs per pinna; stamens 14–20 filaments	C. biflora
5B.	Capitula with (3–) 5–18 flowers; leaves distichously arranged on stems; androecium with 16–50 filaments	6
5A.	Shrub with persistent stems in winter; androecium with 16–27 filaments	C. eriophylla ssp. eriophylla
5B.	Herbaceous, stems arising annually from a taproot or rhizome; androecium with 30–78 stamens	C. humilis ssp. humilis