Selaginella densa

Rydberg

Mem. New York Bot. Gard. 1: 7. 1900.

Common names: Prairie club-moss Rocky Mountains spike-moss
IllustratedEndemic
Synonyms: Selaginella rupestris var. densa (Rydberg) Clute
Treatment appears in FNA Volume 2.

Plants terrestrial or on rock, forming cushionlike or loose mats. Stems decumbent or creeping, not readily fragmenting, irregularly forked, without budlike arrested branches, tips straight; main-stem upperside and underside structurally slightly different, conspicuously indeterminate, lateral branches radially symmetric, conspicuously or inconspicuously determinate, strongly ascending, 2–3-forked. Rhizophores borne on upperside of stems, throughout stem length, 0.2–0.35 mm diam. Leaves essentially monomorphic, in poorly defined pseudowhorls of 5 or 6, tightly appressed, ascending, green, linear to linear-lanceolate, (2.7–) 3–5 × 0.4–0.7 mm (upperside leaves smaller than underside ones, also smaller on ascending buds); abaxial ridges present; base long-decurrent, oblique, and glabrous on underside leaves, slightly decurrent, oblique, and sometimes pubescent on upperside leaves; margins long-ciliate, cilia transparent, mostly ascending or spreading on proximal 1/2, ascending on distal 1/2, 0.07–0.17 (–0.2) mm; apex slightly keeled to plane, rather obtuse, abruptly long-bristled; bristle white or transparent, puberulent, (1–) 1.25–1.9 mm. Strobili solitary, (0.5–) 1–3 (–4) cm; sporophylls ovatelanceolate, seldom ovate, abaxial ridges well defined, base glabrous, margins ciliate entire length or dentate near tip, apex usually long-bristled.


Habitat: Prairies, alpine meadows, dry rocky slopes, rock crevices, sandstone, quartzite or granite rock, and dry gravelly, clayey or sandy soil
Elevation: 1100–4000 m

Distribution

V2 656-distribution-map.gif

Alta., B.C., Man., Ont., Sask., Ariz., Colo., Idaho, Mont., Nebr., N.Mex., N.Dak., S.Dak., Utah, Wyo.

Discussion

Selaginella densa has been treated as including three varieties: var. densa, var. scopulorum (Maxon) R. M. Tryon, and var. standleyi (Maxon) R. M. Tryon (R. M. Tryon 1955), which are recognized here at the species level. Intermediates between S. densa and the other two species of the group may represent ecological variations of the species, hybrids between species within the complex, or hybrids with other closely related species, such as S. watsonii. This group is in need of detailed systematic studies. Megasporangia with only two well-developed megaspores have been observed, which may indicate apogamy and the presence of different races as found in S. rupestris.

Selected References

None.

Lower Taxa

None.

"entire" is not a number.

... more about "Selaginella densa"
long-bristled +, obtuse +, slightly keeled +  and plane +
Iván A. Valdespino +
Rydberg +
glabrous +  and pubescent +
decurrent +  and long-decurrent +
0.1 cm1 mm <br />0.001 m <br /> (0.125 cm1.25 mm <br />0.00125 m <br />) +
transparent;white +
0.125 cm1.25 mm <br />0.00125 m <br /> (0.19 cm1.9 mm <br />0.0019 m <br />) +
0.017 cm0.17 mm <br />1.7e-4 m <br /> (0.02 cm0.2 mm <br />2.0e-4 m <br />) +
transparent +
0.007 cm0.07 mm <br />7.0e-5 m <br /> (0.017 cm0.17 mm <br />1.7e-4 m <br />) +
Prairie club-moss +  and Rocky Mountains spike-moss +
Alta. +, B.C. +, Man. +, Ont. +, Sask. +, Ariz. +, Colo. +, Idaho +, Mont. +, Nebr. +, N.Mex. +, N.Dak. +, S.Dak. +, Utah +  and Wyo. +
1100–4000 m +
Prairies, alpine meadows, dry rocky slopes, rock crevices, sandstone, quartzite or granite rock, and dry gravelly, clayey or sandy soil +
monomorphic +
0.27 cm2.7 mm <br />0.0027 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
fertile +  and vegetative +
linear;linear-lanceolate +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.07 cm0.7 mm <br />7.0e-4 m <br />) +
ciliate +  and serrate +
cushionlike +
globose +, ovoid +  and tetrahedral +
tetrahedral +
Mem. New York Bot. Gard. +
alternating +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.035 cm0.35 mm <br />3.5e-4 m <br />) +
Illustrated +  and Endemic +
adjacently +  and monomorphic +
fertile +  and vegetative +
branched +, not +  and articulate +
dimorphic +, climbing +  and cespitose +
3 cm30 mm <br />0.03 m <br /> (4 cm40 mm <br />0.04 m <br />) +
quadrangular +
1 cm10 mm <br />0.01 m <br /> (3 cm30 mm <br />0.03 m <br />) +
Selaginella rupestris var. densa +
Selaginella densa +
Selaginella subg. Tetragonostachys +
species +
straight +
branched +  and not articulate +
erect +  and creeping +
branched +  and not articulate +
erect +  and creeping +
differentiated +
perennial +  and annual +
on rock +  and terrestrial +
epiphytic +  and hemiepiphytic +
12 +, 11 +, 10 +, 9 +, 8 +  and 7 +