Flora of North America species comparison

dark orange-brown, shallowly furrowed, ridges flat, often peeling into long, thin strips.

with axillary spines.

greenish yellow, becoming orange-brown;

thorns stout, straight, to 1.5 cm, usually lateral to spur branch, spur branches often paired.

often paired, larger one red-brown, globose, 1.5-2 mm;

scales ciliate;

leaf scars half round, bundle scars arranged in oval.

blade 4-12 × 2-6 cm, base rounded, apex acuminate;

surfaces abaxially pale, glabrate, midrib and veins pubescent, adaxially lustrous, glabrous, midrib somewhat pubescent.

blade ovate to lanceolate, not leathery, margins entire, never lobed;

venation pinnate.

flowers borne outside receptacle; staminate inflorescences loose short racemes; pistillate inflorescences dense heads.

staminate and pistillate on different plants.

sepals distinct, yellow-green, ca. 1 mm, apex acute, pubescent;

filaments ca. 2 mm, closely appressed to sepals, flattened.

calyx 4-lobed;

stamens 4, inflexed;

filaments filiform;

anthers introrse, with short connective.

sepals green, obovate, 3 mm, enclosing and closely appressed to ovary, hoodlike, ciliate near tip;

ovary ovoid, compressed, ca. 1 mm;

style base green, ca. 3 mm, branches 4-6 mm, glabrous;

stigma yellowish, papillose.

sepals 4, 2 outer sepals wider than inner ones;

ovary 1, superior, 1-locular;

style unbranched, filiform.

cream colored, oval to oblong, 8-12 × 5-6 mm, base truncate or rounded with 1-3 minute points, margins with narrow groove, apex rounded, mucronate;

surfaces minutely striated or pitted.

inflorescences clustered on lateral spur branches;

peduncle 1-1.5 cm, pubescent;

heads globose or cylindric, 1.3-2.3 cm;

pedicels 2-10 mm, glabrate.

inflorescences: peduncle 2-2.5 mm, glabrous or pubescent;

heads globose, sessile on obconic receptacle, to 1.5 cm diam.

yellow-green to green, spheric, surface irregular, exuding milky sap when broken, peduncle short, glabrous or pubescent;

achenes completely covered by accescent, thickened calyx lobes and deeply embedded in receptacle.

globose, 8-12 cm or more diam.; each achene completely enclosed by its enlarged, fleshy calyx.

buds surrounded by bud scales.