Plants small to medium-sized, green or yellow-green, often with pinkish or reddish tinge. Stems evenly foliate, innovations and fertile stem-leaves similar, innovations not julaceous; rhizoids brown, red, or violet, sometimes hyaline or yellowish-brown. Leaves imbricate to loosely set, slightly twisted when dry, broadly lanceolate to narrowly ovate, flat to weakly concave; base not or weakly decurrent; margins entire to serrulate distally, limbidium usually absent; costa percurrent to long-excurrent; inflated group of pinkish subalar cells absent; medial and distal laminal cells elongate-hexagonal. Specialized asexual reproduction by rhizoidal tubers. Sexual condition dioicous or rarely synoicous. Capsule inclined or nutant, pyriform, 1–3 (–5) mm; hypophysis slender, gradually tapered to seta, never inflated or rugose; peristome usually well developed (occasionally somewhat reduced in G. valparaisense); endostome not adherent to exostome, basal membrane high, segments usually well developed, cilia long, appendiculate (sometimes short or poorly developed in G. valparaisense).

Distribution

Nearly worldwide, except Antarctica, temperate regions, occasionally subtropical regions, absent from arctic-alpine climates

Discussion

Species ca. 50 (9 in the flora).

Despite the early work of A. C. Crundwell and E. Nyholm (1964), the species of sect. Tuberibryum are still not recognized by many North American workers, thus the distributions of many remain poorly known. Many species are weedy and often occur in agricultural fields. Several are likely to have been introduced to North America. Plants of sect. Tuberibryum have red-brown capsules.

Selected References

None.

Lower Taxa

Gemmabryum apiculatum, Gemmabryum demaretianum, Gemmabryum klinggraeffii, Gemmabryum radiculosum, Gemmabryum ruderale, Gemmabryum subapiculatum, Gemmabryum tenuisetum, Gemmabryum valparaisense, Gemmabryum violaceum

Key

1	Rhizoidal tubers usually 120-200(-300) µm, purple-red, orange, yellow, red, or red-brown	> 2
1	Rhizoidal tubers usually smaller than 100(-120) µm, brown, red, crimson, purple-red, yellow, orange-brown, or orange	> 5
2	Rhizoids red-violet to deep red; tubers purple-red or rarely orange.	Gemmabryum ruderale
2	Rhizoids yellow, yellow-red, brown, or red-brown; tubers yellow, orange, red-brown, or red	> 3
3	Rhizoids yellow; tubers yellow to rarely orange.	Gemmabryum tenuisetum
3	Rhizoids yellow-red, brown, or red-brown; tubers red to red-brown	> 4
4	Costae short- to long-excurrent, awns yellow to red; proximal laminal cells quadrate to occasionally short-rectangular; calcareous substrates.	Gemmabryum radiculosum
4	Costae short-excurrent, awns red-brown; proximal laminal cells short- rectangular; siliceous substrates.	Gemmabryum subapiculatum
5	Medial and distal laminal cells (4-)6-8:1, longer than 60 µm; alar cells sometimes differentiated; tubers pyriform, brown; rhizoids brown to red-brown; limbidium absent or present	> 6
5	Medial and distal laminal cells 3-4:1, usually shorter than 60 µm; alar cells similar to adjacent juxtacostal cells; tubers usually irregularly spheric, sometimes pyriform, purple-red, red, crimson, yellow, orange-brown, or orange; rhizoids hyaline, pale yellowish brown, red-brown, pale tan, brown, violet, purple, or rarely red-purple; limbidium absent or rarely indistinct	> 7
6	Medial and distal laminal cells 6-8:1, 60-100(-120) µm; alar cells quadrate; bulbils occasionally present; limbidium absent.	Gemmabryum apiculatum
6	Medial and distal laminal cells usually 4-6:1, 60-80 µm; alar cells rectangular; bulbils absent; limbidium often present.	Gemmabryum valparaisense
7	Rhizoids violet, purple, or rarely red-purple; tubers irregularly spheric, purple-red or rarely orange.	Gemmabryum violaceum
7	Rhizoids hyaline, pale yellowish brown, pale tan, brown, or red-brown; tubers irregularly spheric or pyriform, yellow, orange-brown, red, or crimson	> 8
8	Tubers pyriform, yellow to orange-brown, in clusters of 2-5 on short lateral rhizoids of main rhizoids at stem base.	Gemmabryum demaretianum
8	Tubers irregularly spheric, red to crimson, on long rhizoids in soil.	Gemmabryum klinggraeffii

"narrower" is not a number."narrow" is not a number.