Riella americana M. Howe & Underw.

Riella americana Howe & Underw. Bull. Torrey
Club 30: 218. 1903.
Erect or ascending, 10-30 mm. high, simple or more commonly 1-4 times furcate; axis elliptic in section, 0.2-0.8 mm. wide, mostly 6-10 cells thick, with root-hairs borne only on the basal parts and usually few; wing 2-5 mm. broad, rounded-falciform at apex, slightly undulate-crisped, subentire or erose, tapering towards the base and commonly deficient below the first dichotomy; cells near the axis about 60 jtt in greatest diameter, those near the margin about 40 ix scales few, small, 0.2-0.6 mm. long, linguiform and obtuse or irregularly lanceolate and subacute, those near the growing apex usually intermingled with multicellular gemmae; gemmae trichomic in origin, soon oblpng or orbicular-oblong in outline, showing later a median constriction and becoming finally pandur if orm and subspatulate. Dioicous; antheridia about 0.36 X 0.16 mm., sometimes as many as 75 (including empty locelli) in a single elongated marginal series ; archegonial gametophyte, or each of its branches, maturing for the most part 3-12 sporogonia in acropetal order; involucres smooth, ellipsoid-ovoid or at full maturity subgloboseovoid, 1.4-1.8 X 0.8-1.2 mm., narrowed rather gradually to the truncate or slightly pointed subpapillose orifice; capsule globose, 0.8-1 mm. in diameter, the seta about 0.2 mm. long, mostly a trifle shorter than the ovoid-conic foot; spores dark-brown, 100-130 m in maximum diameter (spines included), the outer face bearing numerous sometimes curved spines 10-24 ti long, with dilated apices, these spines more or less connected by radiating basal membranes
4
fornfeg irregular reticulations, the inner faces bearing conic, non-capitate spines, 3-6 /* long, with basal membranes obsolescent or entirely wanting.
Type I/OCAIvITy: Limpia Canon, Texas. Distribution: Western Texas (to South Dakota ?). IlIvUSTrations : Bull. Torrey Club 30: pi. 11; pi, 12. f. 21, 22.