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SELAGINELLACEAE (Spikemoss Family)

A family of a single genus and about 700-750 species.

Selaginella Beauvois (Spikemoss)

References: Valdespino in FNA (1993b); Tryon (1955); Lellinger (1985); Buck (1977); Somers & Buck (1975). Key adapted in part from Valdespino in FNA (1993b).

A genus of about 700-750 species, cosmopolitan, but mostly tropical.

1. Sterile leaves dimorphic, in 4 ranks, the ventral pair spreading laterally, the dorsal pair ascending; leaves acute, mucronate, lacking a white or translucent apical hair-tip; fertile branch tips strongly differentiated (into strobili) from the sterile portions of the stem......2

1. Sterile leaves monomorphic, spirally arranged around the stems; leaves acuminate and with a white or translucent apical hair-tip (the hair-tip rarely lost); fertile branch tip only slightly differentiated from the sterile portions of the stems......4

3. Lateral leaves of the main stems 2.5-4 mm long, elliptic; lateral stems ascending or erect, 2-6 cm long; rhizophores (modified, leafless, root-producing shoots) borne on the upper side of the stem......S. kraussiana

3. Lateral leaves of the main stem 1-2.5 mm long, ovate; lateral stems creeping (or the tips sometimes slightly ascending), 0.2-1 cm long; rhizophores axillary......S. apoda

5. Stems mostly creeping or turned up at the apex, forming mats 1.5-4 cm high; rhizome or rhizomatous stem absent; aerial roots present all along the stems; budlike arrested branches absent......S. rupestris

5. Stems mostly erect or ascending, forming compact clumps usually more than 4 cm high; rhizome or rhizomatous stem present; aerial roots present only at or near the base of the erect stems; budlike arrested branches present......6

7. Leaves mostly tightly appressed; base conspicuously pubescent; strobili distinctly larger in diameter than the subtending stem; sporophyll apex often recurved......[S. arenicola ssp. arenicola]

7. Leaves mostly loosely appressed; base usually glabrescent; strobili not distinctly larger in diameter than the subtending stem; sporophyll apex usually straight ......[S. arenicola ssp. riddellii]

Selaginella acanthonota Underwood, Spiny Spikemoss, Sand Spikemoss. Cp (NC, SC): sandhills; uncommon. June-August. S. acanthonota ranges from se. NC south to s. FL, west to panhandle FL. The complex comprising S. acanthonota, S. arenicola, and S. riddellii has been controversial. The complex ranges from se. NC south to s. FL and west to c. TX. S. arenicola Underwood ssp. arenicola is more southern, from n. GA south to s. FL and west to e. panhandle FL. S. arenicola ssp. riddellii (Van Eseltine) R. Tryon occurs in TX, OK, AR, LA, AL, and GA. See Tryon (1955) and Valdespino in FNA (1993b) for additional information on the complex. [= FNA, S; S. arenicola-- RAB (infraspecific taxa not distinguished); S. arenicola Underwood ssp. acanthonota (Underwood) R. Tryon -- K]

Selaginella apoda (Linnaeus) Spring, Meadow Spikemoss. Cp, Pd, Mt (NC, SC, VA): seepages, bogs, spray cliffs, stream margins, other moist habitats; common. June-October. Ranging from s. ME, NY, OH, s. IN, AR, and e. OK south to FL, GA, AL, MS, LA, and e. TX. Often overlooked by vascular plant botanists as a moss or liverwort. See the discussion below of two other species closely related to and only rather cryptically differentiable from S. apoda. [= RAB, C, F, FNA, G, K, W; Diplostachyum apodum (Linnaeus) Beauvois -- S]

*Selaginella braunii Baker, Treelet Spikemoss, Braun's Spikemoss. Cp (NC): naturalized around graveyards or gardens; rare, introduced, native of China. [= FNA, K]

*Selaginella kraussiana (Kunze) A. Braun, Krauss's Spikemoss, Mat Spikemoss. Cp (NC, SC, VA?): naturalized around gardens or lawns; rare, introduced. [= FNA, K]

Selaginella rupestris (Linnaeus) Spring, Rock Spikemoss. Pd, Mt (NC, SC, VA): granite flatrocks, other, mostly acidic, rock outcrops, occasionally on greenstone or calcareous shales; common. June-September. Ranging from s. Greenland and Nova Scotia west to Alberta, south to GA, AL, AR, OK, and NE. Valdespino in FNA (1993b) suggests that two or more cryptic or semicryptic species are present within what is currently called S. rupestris. Additional study is needed. [= RAB, C, F, FNA, G, K, S, W]

Selaginella tortipila A. Braun, Twisted-hair Spikemoss. Mt, Pd (NC, SC): rock outcrops, mostly at high elevations; common. July-September. Endemic to the Southern Appalachians (rarely into the Piedmont) of NC, TN, SC, and GA. Occurring close to the VA border; it should be sought there. [= RAB, FNA, K, S, W]

S. arenicola Underwood ssp. arenicola, Sand Spikemoss, ranges from e. GA south to s. FL, se. GA, and Panhandle FL.

S. arenicola Underwood ssp. riddellii (Van Eseltine) R.M. Tryon, Riddell Spikemoss, ranges from e. and c. GA west to TX and OK. It occurs in the Coastal Plain and Piedmont of GA, not far from our area.

S. eclipes W.R. Buck, Hidden Meadow Spikemoss, from NY and the Great Lakes region south and west to the Ozarks, differs from S. apoda in having the dorsal leaves with long attenuate apices with a well-developed midrib (vs. with acute apices, or if attenuate, then usually keeled and without a well-developed midrib), and the mature megaspores shiny, the reticulation lax (observed at 40H) (vs. dull and closely reticulate). Given its semi-cryptic separation from S. apoda, it could easily be present in our area.

S. ludoviciana (A. Braun) A. Braun, Gulf Spikemoss, Louisiana Spikemoss, occurs on the Gulf Coastal Plain from n. FL west to e. LA; it differs from S. apoda in having leaves with margins of 3-5 rows of transparent (hyaline) cells (vs. margins undifferentiated or with 1-2 rows of slightly paler cells) and stomates of lateral leaves confined to near the midrib on the upper surface (vs. stomates distributed over entire upper surface).

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Flora of the Carolinas and Virginia, Working Draft of 27 October 1997 -- KEY TO PTERIDOPHYTE GENERA. Alan S. Weakley. The Nature Conservancy, Southeast Regional Office, Southern Conservation Science Department.