Dendroceros

Dendroceros is a genus of hornworts in the family Dendrocerotaceae. The genus contains about 51 species native to tropical and sub-tropical regions of the world.

Description
The epiphytic and epiphyllous Dendroceros is the only desiccation-tolerant hornwort genus. The gametophyte is yellowish-green and usually less than one-half cm wide. The thallus branches in a bifurcating pattern. In the subgenus Apoceros, there are cavities in the central strand of the thallus. The edges of the thallus are only a single layer of cells thick and have an undulating margin. It is common to find symbiotic colonies of blue-green bacteria (usually Nostoc) growing among the cells. Under a microscope, the epidermal cells have trigones.

The sporophyte is erect when mature, growing up to 5 cm tall. Unlike many hornworts, the surface of the Dendroceros sporophyte lacks stomata, as do the sporophytes of the related genera Megaceros and Nothoceros.  The interior of the sporophyte differentiates into a central column and a surrounding mass of spores and elater cells, with a distinct spiral. The spores are green and multicellular with an ornamented surface.

Classification
Current classification by Söderström et al. 2016.

Genus Dendroceros Nees 1846
 * D. australis Stephani 1909
 * D. crassicostatus Stephani 1917
 * D. exalatus Stephani 1909c
 * D. gracilis Stephani 1917b
 * D. humboldtensis Hürlimann 1960
 * D. rarus Stephani 1917b
 * D. reticulus Herzog 1950b
 * D. subtropicus Wild 1893
 * D. tahitensis Ångström 1873
 * D. vesconianus Gottsche ex Bescherelle 1898
 * D. wattsianus Stephani 1909
 * Subgenus (Cichoraceus) Peñaloza-Bojacá & Maciel-Silva 2019
 * D. cichoraceus (Montagne 1845) Stephani 1916
 * Subgenus (Dendroceros) Nees 1846
 * D. acutilobus Stephani 1909
 * D. adglutinatus (Hooker & Taylor 1845) Gottsche, Lindenberg & Nees 1846
 * D. allionii Stephani 1917
 * D. breutelii Nees 1846
 * D. crassinervis (Nees 1846) Stephani 1917
 * D. crispus (Swartz 1788) Nees 1846
 * D. foliicola Hasegawa 1980
 * D. herasii Infante 2010
 * D. javanicus (Nees 1830) Nees 1846
 * D. paivae Garcia, Sérgio & Villarreal 2012
 * D. rigidus Stephani 1917
 * D. subplanus Stephani 1909
 * D. tubercularis Hattori 1944
 * D. validus Stephani 1917
 * Subgenus (Nodulosus) Peñaloza-Bojacá & Maciel-Silva 2019
 * D. africanus Stephani 1917
 * D. borbonicus Stephani 1892
 * D. crispatus (Hooker 1830) Nees 1917
 * D. granulatus Mitten 1871
 * D. japonicus Stephani 1909
 * Subgenus (Apoceros) Schuster 1987b
 * D. cavernosus Hasegawa 1980
 * D. cucullatus Stephani 1923
 * D. difficilis Stephani 1917
 * D. muelleri Stephani 1889
 * D. ogeramnangus Piippo 1993
 * D. pedunculatus Stephani 1909
 * D. seramensis Hasegawa 1986
 * D. subdifficilis Hattori 1951

Habitat
Dendroceros grows on humid ground, rocky outcrops, and on the sides of trees. Its name literally means "tree horn".