1A.	Flowers arranged in spikes; receptacle 1 cm or longer; fruit dehiscent only through ventral suture, valves woody, rigid, not flexible	P. lanceolatum
1B.	Flowers arranged in spherical capitula or compact spikes; receptacle 1 cm long or shorter; fruit dehiscent through both sutures, stiff and leathery but flexible when pressed	2
2A.	Peduncles 2–4, 1.5 cm long or shorter; ovary stipe 1.9 mm or shorter, body thinly minutely papillated-puberulent; flowers in dense capitula, perianth gray, silky, puberulent	P. dulce
2B.	Peduncles solitary, (1.5) 2–3 cm long; stipe of ovary variable, up to 3 mm long, when shorter than 2 mm, body glabrous or micro-papillate (under microscope at high magnification); flowers in spherical or spiked flower heads, if capitate, the ovary glabrous or slightly strigulous or if pubescent, the largest flower at least 2.5 mm long	P. unguis-cati