Selaginella mutica

Selaginella mutica D.C. Eaton ex Underw.
(Latin: muticus, shortened, curtailed, = blunted, without a point)

Local names: blunt spike-moss

Plants mat-forming, the mats usually rather loose; stems prostrate-creeping with leaves without strongly upswept or upwardly curving appearance, the leaf-covered stems therefore appearing radially symmetrical; rhizophores scattered along entire length of stem; leaves tightly appressed, all of one kind, linear-lanceolate to lanceolate or lanceolate-elliptic, marginally ciliate to minutely denticulate, basally usually rounded and adnate, apically with bristle usually absent or less than 0.1 mm long, rarely to 0.45 mm; strobili solitary, quadrangular, (6–)10–30 mm long; sporophylls ovate-lanceolate to deltate-ovate, apically without bristle or bristle very short. On rock or terrestrial; rocky slopes, cliffs, ledges, canyons, often on igneous rocks, but sometimes on other substrates (e.g., limestone, sandstone); known in TX only from scattered localities in the w Trans-Pecos; AZ, CO, NM, UT, TX, WY; also state of Chihuahua in n Mexico. Sporulating Apr–Oct. [Bryodesma muticum (D.C. Eaton ex Underw.) Sojak] Selaginella mutica is often found growing with S. underwoodii and S. ×neomexicana (and has thus been hypothesized to be a parent of S. ×neomexicana). It is sometimes confused with S. viridissima because they both typically have leaves without bristles at the apex; however, the creeping habit distinguishes S. mutica from the erect S. viridissima. Velaspino (1993) noted that there are “two rather distinct, morphological extremes” within S. mutica which are often recognized as varieties (as done here); the two varieties are not distinguished on the county distribution map. Some specimens have leaves with long spreading cilia and a short often broken apical bristle (treated by Correll as var. texana); however, Velaspino (1993) noted that they belong in var. mutica. Mickel and Smith (2004) described S. mutica as “a very distinct taxon” with “tightly appress occurring in a narrow strip of territory along the Mexican border”). Differing from var. mutica as given in the key; leaves with apical bristle definitely present, the leaf and sporophyll margins mostly with very short, ascending cilia, but the cilia rarely longer in forms sometimes recognized as var. texana. The type description (Weatherby 1944) cites specimens from Mt. Franklin, El Paso Co. (Slater s.n., 1924, US [also Correll 15027, TEX-LL; Warnock 23890, SRSC]) and the Davis Mts., Jeff Davis Co. (Moore & Steyermark 2046, in part, G, E.J. Palmer 31951, US [also Correll 13514, TEX-LL]), and the type of the synonym S. mutica var. texana is from the Chicos Mts., Brewster Co. (Moore & Steyermark 3196, US, MO). Yarborough and Powell (2002) noted that TX collections of this variety are “mainly from the Mt. Livermore area of the Davis Mts., Jeff Davis Co. where the variety is often found in mixed mats with S. underwoodii”; AZ, NM, TX. [S. mutica var. texana Weath.] Weatherby (1944), who named S. mutica var. texana (which we are treating as a synonym of var. limitanea), noted that “This is a rather indefinite variety, combining the long, spreading cilia of typical S mutica and the terminal seta of var. limitanea, and known only from west Texas where the ranges of the two meet. Morphologically, it is little more than a series of intermediates between them….” Carr (2002a) listed var. limitanea as one of only two Selaginella taxa on his list of rare plants of TX; we thus consider it to be of conservation concern. (Carr 2002a: G4T3S3)

var. mutica. Scattered in the w Trans-Pecos (e.g., Culberson Co., J.L. Blassingame 3212, BRIT); AZ, CO, NM, UT, TX, WY; also n Mexico. [S. watsonii Underw. var. mutica (D.C. Eaton ex Underw.) Clute] Yarborough and Powell (2002) noted that two Sul Ross (SRSC) collections from the Chisos Mts., Brewster Co. “show intermixing with S. underwoodii.”

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