Takakia
Takakia | ||||||||||||
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Systematics | ||||||||||||
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Scientific name of the subdivision | ||||||||||||
Takakiophytina | ||||||||||||
Stech & W. Frey | ||||||||||||
Scientific name of the class | ||||||||||||
Takakiopsida | ||||||||||||
Stech & W. Frey | ||||||||||||
Scientific name of the order | ||||||||||||
Takakiales | ||||||||||||
Stech & W. Frey | ||||||||||||
Scientific name of the family | ||||||||||||
Takakiaceae | ||||||||||||
Stech & W. Frey | ||||||||||||
Scientific name of the genus | ||||||||||||
Takakia | ||||||||||||
S. Hatt. & Inoue |
The moss genus Takakia comprises two species with mainly Asian distribution and alone forms the subdivision Takakiophytina . Due to the unique combination of characteristics of the liverwort in the gametophyte and those of the deciduous moss in the sporophyte , the genus is systematically very isolated.
features
These mosses have underground stolons, trunks without rhizoids and with a central strand. The leaflets are divided into four rows of cells and stand in three rows. The plants have mucous hairs. One species does not grow with a vertex cell , but with an apical meristem .
The number of chromosomes is n = 4.
The genus has characteristics of both the mosses and the liverworts .
Liverwort characteristics
- Central strand in the Seta
- Hydroids in the stem
- The leaflets are split into single rows
- Rhizoids are absent
- Presence of stolons
- Mucous papillae
So most liverwort features appear in the gametophyte .
Deciduous moss characteristics
- Poorly developed Columella
- Cap-shaped kalyptra
- The spores are formed according to the seta
- The sporophyte is persistent
- Ultrastructure of the spermatozoids
- Development of the Antheridia
- Development of the Sporophyte
- Cell network of the lamina of the leaflets
- Oil drops instead of oil bodies
- Gametophyte-Sporophyte Connection
Most of the deciduous moss traits appear in the sporophyte.
Systematics
The genus consists of two types:
- Takakia ceratophylla (middle) Grolle - area from the Himalayas and Borneo via Japan to British Columbia
- Takakia lepidizoides S. Hatt. & Inoue - Japan
The systematic position of the genus has not yet been conclusively clarified. One reason is that the genus was first described in 1951 using a sterile gametophyte. Only the discovery of Archegonium cleared the position as moss. First, the genus was placed among the Calobryales within the liverwort. Antheridia have only been known since 1988; the first sporophyte was found in 1990. Due to the fact that the capsule opens with a longitudinal slit, Takakia was then placed as a subclass to the Andreaeopsida . Today it is considered a separate subdivision Takakiophytina.
literature
- Jan-Peter Frahm : Biology of Mosses. Spectrum Akademischer Verlag, Heidelberg et al. 2001, ISBN 3-8274-0164-X .
Individual evidence
- ↑ Wolfgang Frey, Michael Stech, Eberhard Fischer: Bryophytes and Seedless Vascular Plants (= Syllabus of Plant Families. 3). 13th edition. Borntraeger, Berlin et al. 2009, ISBN 978-3-443-01063-8 , pp. 124-127.
Web links
- Takakiaceae at the Missouri Botanical Garden