Marie L. Hicks
Jungermannia subg. Jamesoniella Spruce
Plants prostrate or forming thick mats or caespitose turfs, green to reddish brown or purplish black in exposed sites. Stems ascending to erect or prostrate, with few terminal or intercalary branches, either lateral or ventral; sub floral innovations common; rhizoids scattered on ventral stem surface, colorless. Leaves alternate, succubous oblique, ovate to quadrate rotundate, entire, rarely with retuse apices; leaf cell walls moderately thickened; trigones present; oil bodies finely granular, more than 5 per cell. Underleaves absent, or vestigial, occasional and very small, hidden among rhizoids. Specialized asexual reproduction absent. Sexual condition dioicous. Androecia terminal, becoming intercalary; bracts saccate at base with an infolded dorsal tooth; antheridia 1 2 per bract, stalk 2 or 4 seriate. Gynoecia terminal on main shoot; bracts entire to dentate, laciniate or ciliate on lateral margins; bracteole present, dentate to laciniate ciliate; perianth exerted 1/2 or more above bracts, inflated, oblong to fusiform, smooth cylindrical below, 4 5 plicate distally, narrowed to a ciliate or dentate crenulate mouth; perigynium absent. Sporophyte seta massive, of numerous cell rows; capsule ovoid, 4 valved, walls 4 5-stratose; epidermal cells with nodular thickenings, inner cells with semi annular bands; elaters 150 200 × 8 µm, 2 spiral; spores 10 15 µm, finely granular papillose.
Species 14 (2 in the flora): tropical and temperate areas of North America, Mexico, Central America, South America, Europe, Asia; s Africa, Australia, Pacific Islands (New Zealand).
This genus is easily recognized when fruiting by the dentate to laciniate bracts and bracteole, not found in other entire leaved genera in the flora. Sterile material may be separated from Odontoschisma by the larger number of smaller oil bodies in leaf cells of Jamesoniella.
Schuster, R.M., 1983, New Manual of Bryology 1: 605. Nichinan.