Flora of North America species comparison

green to brown, glabrous or puberulent, without long, jointed hairs;

thorns 1 or 2 per node, 6–15 × 0.5–1.2 mm.

blades lanceolate, 3–10 × 1–2 cm, base attenuate to acute, margins entire or serrulate, surfaces glabrous.

axillary, fasciculate, 1–10-flowered, or on short, leafy branches.

sepals broadly lanceolate to ovate, 5–8 × 1.5–4 mm, glabrous or puberulent, without glandular trichomes;

corolla blue, occasionally white, petals 7–11 × 4–6 mm;

ovary glabrous;

styles 2, 3.5–5 mm, glabrous.

globose, 4–6 mm wide, glabrous.

ovoid, 0.5–0.6 × 0.2–0.3 mm.

= 20.