Flora of North America species comparison

alternate or whorled, rigid, angle of divergence about 30°.

opposite or whorled, rigid, angle of divergence about 30°.

pale green, becoming yellow, then gray with age, glaucous, with numerous very fine longitudinal grooves;

internodes 3–10 cm.

pale to dark green, becoming yellow with age, not viscid, slightly to strongly scabrous, with numerous longitudinal grooves;

internodes 1–6 cm.

in whorls of 3, 5–15 mm, connate to 1/2–3/4 their length;

bases becoming gray and shredded with age;

apex spinose.

opposite (rarely in whorls of 3), 1–3(–5) mm, connate to 1/2–7/8 their length;

bases thickened, brown, shredding with age, ± persistent;

apex obtuse.

1–several at node, obovoid, 6–10 mm, on short, scaly peduncles;

bracts in 8–12 whorls of 3, reddish brown, obovate, slightly clawed, 3–4 × 2–3 mm, membranous;

bracteoles nearly equaling bracts;

sporangiophores 4–5 mm, exserted to 1/4 their length, with 4–5 short-stalked microsporangia.

2 (rarely 1 or whorled) at node, obovoid, 4–7 mm, sessile or rarely on short peduncles;

bracts opposite, 6–10 pairs, yellow to red-brown, obovate, 3–4 × 2–3 mm, membranous;

bracteoles slightly exceeding bracts;

sporangiophores 4–5 mm, 1/2 exserted, with 4–6 sessile to short-stalked (less than 1 mm) microsporangia.

cones 1–several at node, obovoid, 10–15 mm, on short, scaly peduncles (rarely sessile);

bracts in 6–9 whorls of 3, circular, 8–12 × 8–12 mm, papery, translucent with reddish brown center and base, base clawed, margins entire.

cones usually 2 at node, ovoid, 6–10 mm, sessile or on short, scaly peduncles;

bracts opposite, 5–7 pairs, circular, 4–7 × 2–4 mm, membranous, with red-brown thickened center and base, margins entire.;

seed 1, ellipsoid, 5–8 × 2–4 mm, light brown to brown, smooth to slightly scabrous.

buds spinelike, to 10 mm.

buds conic, 1–2 mm, apex obtuse.