''Dendroceros'' is a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
hornwort
Hornworts are a group of non-vascular Embryophytes (land plants) constituting the division Anthocerotophyta (). The common name refers to the elongated horn-like structure, which is the sporophyte. As in mosses and liverworts, hornworts have a ...
s in the
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Dendrocerotaceae
The Dendrocerotaceae is the only family of hornwort
Hornworts are a group of non-vascular Embryophytes (land plants) constituting the division Anthocerotophyta (). The common name refers to the elongated horn-like structure, which is the spor ...
.
[Renzaglia, Karen S. & Kevin C. Vaughn. (2000) "Anatomy, development and classification of hornworts", pages 1-20 ''in'' A. Jonathan Shaw & Bernard Goffinet (Eds.), ''Bryophyte Biology''. (Cambridge: Cambridge University Press). ] 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
A gametophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has on ...
is yellowish-green and usually less than one-half cm wide. The
thallus
Thallus (plural: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. Many of these organisms wer ...
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
''Nostoc'', also known as star jelly, troll’s butter, spit of moon, fallen star, witch's butter (not to be confused with the fungi commonly known as witches' butter), and witch’s jelly, is the most common genus of cyanobacteria found in vari ...
'') growing among the cells. Under a microscope, the epidermal cells have
trigones.
The
sporophyte
A sporophyte () is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.
Life cycle
The sporophyte develops from the zygote pr ...
is erect when mature, growing up to 5 cm tall. Like other hornworts, its surface has
stomata
In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bor ...
. The interior of the sporophyte differentiates into a central column and a surrounding mass of
spore
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
s and
elater
An elater is a cell (or structure attached to a cell) that is hygroscopic, and therefore will change shape in response to changes in moisture in the environment. Elaters come in a variety of forms, but are always associated with plant spores. In m ...
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".
References
External links
{{Plant classification
Hornworts
Taxa named by Christian Gottfried Daniel Nees von Esenbeck
Bryophyte genera