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 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 Peñaloza-Bojacá & Maciel-Silva 2019
  • * D. cichoraceus Stephani 1916
  • Subgenus Nees 1846
  • * D. acutilobus Stephani 1909
  • * D. adglutinatus Gottsche, Lindenberg & Nees 1846
  • * D. allionii Stephani 1917
  • * D. breutelii Nees 1846
  • * D. crassinervis Stephani 1917
  • * D. crispus Nees 1846
  • * D. foliicola Hasegawa 1980
  • * D. herasii Infante 2010
  • * D. javanicus 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 Peñaloza-Bojacá & Maciel-Silva 2019
  • * D. africanus Stephani 1917
  • * D. borbonicus Stephani 1892
  • * D. crispatus Nees 1917
  • * D. granulatus Mitten 1871
  • * D. japonicus Stephani 1909
  • Subgenus 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".