1 | Secondary ridges of fruit with a double row of spines; mericarps almost flattened dorsally; styles short and thick |
1' | Secondary ridges of fruit with a single row of spines; mericarps not strongly compressed dorsally; styles usually long and slender |
2 | Umbels sessile or subsessile, without obvious stalks |
2' | Umbels distinctly stalked |
3 | Stems decumbent or sprawling, 2-20(-35) cm high; leaves rather fleshy with blunt segments; umbels with few, conspicuously unequal rays; bracts and bracteoles entire or shortly 3-fid; fruit c. 7 mm long |
3' | Stems erect or ascending; leaves and umbels not as above; fruit 2-5 mm long |
4 | Stems usually less than 10 cm high, shorter than the long (6-16 cm) naked peduncles; umbels with few (3-5) rays; bracts pinnatisect, much exceeding umbellules at anthesis; petals small, subequal |
4' | Stems usually more than 10 cm high, longer than the peduncles; umbels 6-many-rayed; petals unequal, often radiant |
5 | Leaf-segments and bracts narrowly linear or filiform; flowers and fruits becoming yellow when dried; central fruit of each umbellule subsessile and tuberculate |
5' | Leaf-segments and bracts broader; flowers rarely yellowish when dried; fruits reddish-purple or pale brown, central fruit of each umbellule not as above |
6 | Spines of mature fruit distinctly confluent-winged at the base; plants generally 15-30(-50) cm high, usually branched; involucre not conspicuous |
6' | Spines of mature fruit not or very narrowly confluent-winged at base; involucre often conspicuous |
7 | Plants slender, usually 10-30 cm high; rays 6-12, not becoming very erect or crowded in fruit; fruit spines 2-3 mm long, distinctly glochidiate |
7' | Plants robust, up to 200 cm high; rays usually very numerous, becoming erect and crowded in fruit; fruit spines short, generally less than 2 mm long, obscurely glochidiate |
8 | Stems rather slender, usually less than 100 cm high, often distinctly flexuous, retrorse-hispid or subglabrous; ultimate segments of leaves up to 3 mm wide |
8' | Stems robust, usually more than 100 cm high, often erect and not distinctly flexuous, glabrous or thinly retrorse-hispid; ultimate segments of leaves 5-13 mm wide |