Selaginella hansenii
Selaginella weatherbiana
Hansen's spike-moss
Weatherby's spike-moss
not readily fragmenting, prostrate, upperside and underside structurally different, irregularly forked, branches determinate, tips upturned.
radially symmetric, underground (rhizomatous) and aerial, not readily fragmenting, irregularly forked; rhizomatous and aerial stems often with 1 branch arrested, budlike, tips straight;
aerial stems erect, less often ascending, cespitose, stout, branches not conspicuously arrested, budlike branches mostly near base.
with underside leaves slightly longer and narrower than upperside leaves, otherwise monomorphic, not clearly ranked, tightly appressed, ascending, green or green with red spots, or reddish, linear-lanceolate (underside) to linear-triangular (upperside), (2–)3–4.5 × 0.5–0.6 mm;
abaxial ridges present;
base abruptly adnate, pubescent (sometimes glabrous);
margins ciliate, cilia white to white opaque, strongly appressed and ascending, 0.03–0.1 mm;
apex with bristle white to white-opaque, 0.5–1.4 mm (those on underside leaves sometimes 1/4–1/2 longer than those on upperside leaves).
dimorphic, not clearly ranked.
solitary, 5–7 mm;
sporophylls ovate-deltate to ovate-triangular, abaxial ridges not prominent, base glabrous, margins short-ciliate, apex bristled.
solitary, (0.7–)1–3 cm;
sporophylls narrowly ovate-lanceolate to lanceolate, abaxial ridges prominent, base glabrous, margins denticulate to short-ciliate, apex keeled, bristled.
borne on upperside of stems, throughout stem length, 0.25–0.45 mm diam.
borne on upperside of stems, mostly restricted to rhizomatous stems or to lower 1/2 of aerial stems, 0.16–0.26(–3) mm diam.
stem leaves persistent, loosely appressed, ascending, often incurved, scalelike.
stem leaves tightly appressed, ascending, green, linear-lanceolate to narrowly lanceolate, 1.7–2.4 × 0.36–0.43 mm;
abaxial ridges prominent;
base cuneate and decurrent on main stem or rounded and abruptly adnate on apical branch portions, glabrous or pubescent;
margins short-ciliate at base, cilia transparent, spreading, denticulate, and ascending toward apex, 0.03–0.06 mm;
apex keeled;
bristle transparent to opaque or yellowish to brownish (on old leaves), puberulent to smooth, 0.3–0.6(–0.7) mm.
= 18.
Selaginella hansenii
Selaginella weatherbiana
Leaf dimorphism in Selaginella hansenii is only slightly and inconsistently expressed; the upperside leaves tend to be more lanceolate, short, and slightly thick, whereas the underside leaves tend to be more linear, longer, and thinner, but in some specimens the leaves are monomorphic. Red leaves are rare within Selaginella subg. Tetragonostachys, otherwise found in the flora only occasionally in S. rupestris. Such leaves are more common in S. steyermarkii Alston from southern Mexico and Guatemala and S. sartorii Hieronymus from Mexico.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
One of the most striking features of Selaginella weatherbiana is that at branch forks the larger branch continues to grow as a vegetative shoot, and the smaller one usually forms a strobilus. Therefore, the strobili appear to be lateral rather than terminal. Selaginella weatherbiana grows in close association with S. underwoodii (R. M. Tryon 1955). The two species (as well as S. mutica var. mutica) are very often mixed on herbarium specimens.
Of conservation concern.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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