Flora of North America species comparison

procumbent to erect, infrequently prostrate, green, often becoming red or purple, especially at apex of segments, around flowers, and at sepal tips, simple or with primary and secondary branches, rarely with tertiary branches except when damaged, 5–26 cm, ultimate branches usually short;

leaf and bract apices obtuse to subacute, not mucronate.

erect, green sometimes becoming red, simple or with primary and secondary branches, 5–60 cm, ultimate branches short or long;

leaf and bract apices acute, sharply mucronate.

± torulose, 0.7–5 cm, with (3–)5–10(–14) fertile segments;

bracts covering only base of cymes.

cylindric and slightly torulose, 2–10 cm, with 5–25 fertile segments;

bracts almost obscuring cymes.

segments (2d–4th in main spikes) 2.9–5.2 × 2.4–4(–4.3) mm, usually slightly longer than wide, widest distally, margins 0.2–0.3 mm wide, scarious.

segments 4–5 × 4.5–6.2 mm, wider than long, widest distally, margins ca. 0.5 mm wide, scarious.

flowers semicircular distally, 1.5–2.6 × 1.4–2.4 mm, usually longer than wide, usually larger than lateral flowers and not reaching top of segment;

anthers commonly not exserted, (0.1–)0.2–0.3 mm, usually dehiscing within flowers.

flower semicircular distally, 2.2–2.8 × 2–2.8 mm, about as long as wide, usually reaching top of segment, only slightly larger than lateral flowers;

anthers exserted, dehiscing after exsertion.

= 18.

= 36.