Selaginella hansenii
Selaginella kraussiana
Hansen's spike-moss
Krauss' spikemoss, mat spike-moss
not readily fragmenting, prostrate, upperside and underside structurally different, irregularly forked, branches determinate, tips upturned.
long-creeping, branched, branches 3-forked, flat, articulate, glabrous.
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).
delicate, papery.
solitary, 5–7 mm;
sporophylls ovate-deltate to ovate-triangular, abaxial ridges not prominent, base glabrous, margins short-ciliate, apex bristled.
solitary, 0.2–2.5 cm, with only 1 megasporangium, megasporangium basal;
sporophylls keeled, dentate, strongly tapering toward apex, base glabrous, margins denticulate, apex acuminate;
megasporophylls larger than microsporophylls, in groups of 4, 2 like vegetative leaves, 2 like sporophylls, of the latter 1 large, lanceolate-elliptic, 1 smaller, falcate-lanceolate;
microsporophylls lanceolate to narrowly ovate-lanceolate.
borne on upperside of stems, throughout stem length, 0.25–0.45 mm diam.
borne on upperside of stems throughout stem length, 1–3 mm diam.
leaves nearly perpendicular to stem, well spaced, green, lanceolate, 2.5–3.6 × 0.8–1.2 mm;
base rounded;
margins slightly transparent to green, dentate;
apex acute.
leaves lanceolate to linear-lanceolate, 2–2.7 × 0.6–0.8 mm;
base with small outer auricle;
margins slightly transparent to green, dentate;
apex acuminate.
= 20.
Selaginella hansenii
Selaginella kraussiana
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.)
Selaginella kraussiana has escaped from cultivation and is naturalized in central Georgia, and probably farther south and west. It has been reported as far north as coastal central California and northern Virginia (D. B. Lellinger 1985), but I have not seen specimens from these areas. Selaginella kraussiana is frequently cultivated and has several cultivars. It is widely used in morphologic and anatomic research and for teaching purposes. This species belongs to the series Articulatae Spring, a very distinct group of heterophyllous selaginellas with rhizophores on the upper side of the stem, special microsporangium type and dehiscence (P. Somers 1982), basal megasporangia, the largest megaspores in the genus, mostly spiny microspores, and usually more than one meristele. These and other characteristics suggest that series Articulatae probably deserves subgeneric ranking.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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