Bryol. Europ.3: 211, plates 288 – 290. 1844
Nearly worldwide, alpine, subalpine, and temperate to subarctic regions.
Species 10 (5 in the flora).
Species of Tetraplodon are entomophilous and coprophilous although apparently restricted to the dung of carnivores, bones, and owl pellets. The hypophysis is well developed, elongate, and usually wrinkled when dry; the exostome teeth are connate in 4’s when young but in 2’s as they age; and the seta is stout.
|1||Leaves long-lanceolate; margins with large teeth, occasionally entire.||Tetraplodon angustatus|
|1||Leaves ovate or oblong-ovate; margins entire or nearly so||> 2|
|2||Capsules cleistocarpous, clear pale yellow to stramineous; hypophysis conspicuously narrower than urn.||Tetraplodon paradoxus|
|2||Capsules not cleistocarpous, usually reddish to black, rarely yellow to stramineous; hypophysis usually as wide or wider than urn||> 3|
|3||Setae shorter than 1 cm; leaf apices broadly acute; costae ending before subula.||Tetraplodon urceolatus|
|3||Setae 1-5 cm; leaf apices subulate or acuminate; costae ending in subula||> 4|
|4||Leaf apices abruptly subulate; capsules red, dark red to black with age.||Tetraplodon mnioides|
|4||Leaf apices acuminate; capsules pale yellow to stramineous.||Tetraplodon pallidus|