Selaginella apoda
Selaginella kraussiana
meadow spike-moss, sélaginelle apode
Krauss' spikemoss, mat spike-moss
prostrate to short-creeping, sparsely branched, branches mostly simple or 1-forked, flat, not articulate, glabrous.
long-creeping, branched, branches 3-forked, flat, articulate, glabrous.
delicate, papery.
delicate, papery.
paired or solitary, lax, flattened, 1–2 cm;
sporophylls ovate to ovate-deltate, strongly keeled, keel dentate, base slightly cordate to rounded, margins with scattered teeth, apex acuminate;
megasporophylls larger and wider than microsporophylls, usually on underside of strobili.
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.
axillary, throughout stem length or restricted to proximal 1/3 of stem, 0.05–0.1 mm diam.
borne on upperside of stems throughout stem length, 1–3 mm diam.
leaves distant, green, ovate to ovate-lanceolate, 1.35–2.25 × 0.75–1.35 mm;
base slightly cordate;
margins green or with 1 row of transparent cells, serrate;
apex acute, ending in teeth.
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 ovate-lanceolate, 1–1.6 × 0.45–0.7 mm;
base oblique on inner side, rounded and prominent on outer side;
margins green or with row of transparent cells, serrate;
apex straight, acuminate to long-acuminate.
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 apoda
Selaginella kraussiana
Selaginella apoda is the central component of a taxonomically difficult species complex of eastern North America. It is closely related to S. eclipes (see discussion) and S. ludoviciana. Naturally occurring and experimental hybrids between S. apoda and S. ludoviciana have been reported (P. Somers and W. R. Buck 1975; T. R. Webster 1990). Also, some evidence indicates that hybrids may occur between S. apoda and S. eclipes. More studies are needed in this complex.
The species in the S. apoda complex may be best classified under subg. Homostachys of J. G. Baker (1883, 1887), with which they share flattened strobili and larger sporophylls (megasporophylls) that are usually in the same plane as the vegetative lateral leaves. They are, however, treated here with the other heterophyllous species of subg. Stachygynandrum until a reassessment of the classification of the genus Selaginella can be made.
(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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