Thuidium delicatulum
in P. Bruch and W. P. Schimper, Bryol. Europ. 5: 164. 1852.
Plants green or yellowish brown. Stems 3–8 cm, 2- or 3-pinnate, ± frondose; paraphyllia usually papillose at cell ends. Stem leaves ± erect, appressed when dry, erect-spreading when moist, triangular-ovate, not plicate, 0.6–1.5 mm; margins revolute throughout, papillose-serrulate; apex acuminate; costa ending well before apex; distal laminal cells irregularly oblong-hexagonal or rhombic, 6–10 × 8–12 µm, papillae sometimes 2-fid, not appearing multipapillose. Branch leaves apical cell truncate, multipapillose. Primary branch leaves to 0.5 mm; costa 1/2–2/3 leaf length. Secondary branch leaves 0.3 mm; apex acute; costa to 1/2 leaf length. Perichaetial leaves to 5 mm, margins not ciliate to ciliate proximally, often denticulate distally. Seta 1.5–4.5 cm. Capsule 1.8–4 mm; operculum 0.7–2 mm, long-rostrate; endostome cilia in groups of 2 or 3. Spores 12–24 µm, smooth.
Distribution
North America, Mexico, Central America, n South America, Europe, Asia.
Discussion
Varieties 10 (2 in the flora).
Thuidium delicatulum, if confused with T. recognitum, can be recognized by the stem leaves erect or erect-spreading when moist, not plicate and rather gradually acuminate, with margins recurved to the base of the acumen and costa ending well before the apex. The paraphyllia have small papillae along the cell midpoints. The laminal cells are stoutly 1-papillose, but often, especially in the South, the papillae are 2-fid. The branch leaf laminal cells are rhombic, 6–8 × 8–12 µm, with curved papillae. The operculum is long-rostrate.
Selected References
None.
Key
| 1 | Stem leaf apices not ending in hyaline point of 1-seriate cells; perichaetial leaf margins ciliate proximally. | Thuidium delicatulum var. delicatulum |
| 1 | Stem leaf apices ending in hyaline point of 1-seriate cells; perichaetial leaf margins usually not ciliate, sometimes sparsely so. | Thuidium delicatulum var. radicans |