Flora of North America species comparison

emerging near origin, or growing through cortex and emergent some distance from origin.

on substrate surface.

present or absent, mainly protostelic, in some species becoming actino- or plectostelic, on substrate surface or subterranean, or forming stolons.

present or absent, simple or branched, branching pattern dichotomous and sometimes pseudomonopodial;

leaves uniform or dimorphic or trimorphic.

clustered, 0.6–1.2 cm diam., dominant main shoot with 3–6 branches mostly in lower 1/2.

simple or branched, usually conspicuously leafy at least at base; abscising gemmae formed by reduced lateral shoots.

round or flat in cross section;

leaves on subterranean parts flat, appressed, nonphotosynthetic, and scalelike;

leaves on aerial parts appressed, ascending, or spreading, with 1 central unbranched vein, needlelike to lanceolate to ovate, remote to dense and imbricate, with or without basal and/or mucilage canals.

few and like upright shoots;

annual bud constrictions abrupt, branchlets mostly spreading.

spreading, often somewhat ascending in distal 1/3 of branches, medium green, linear, 4–6 × 0.4–0.8 mm;

margins entire;

apex with narrow hair tip 2.5–4 mm.

3.5–12.5 cm, with remote pseudowhorls of appressed leaves, loosely branched into 2–5 alternate stalks, 0.5–0.8 cm.

2–5 on alternate stalks (if double, usually with stalks 5–8 mm), 15–25 × 3–6 mm.

sessile or stalked, upright, nodding, or pendent.

solitary, adaxial near leaf base or axillary; subtending leaves (sporophylls) unmodified and photosynthetic to much modified, nonphotosynthetic, reduced, and aggregated in strobili;

sporangia reniform to globose, thick-walled with hundreds of spores, outer walls variously modified.

all 1 kind, trilete, thick-walled, surfaces pitted to small-grooved, rugulate, or reticulate.

1.5–2.5 mm, apex abruptly reduced to hair tip.

subterranean and nonphotosynthetic or surficial and photosynthetic.

= 68.