Theca
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217313989
2008-06-05T14:24:08Z
Dumelow
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remove link to dab page (filament is covered in the anther article)
{{Unreferenced|date=January 2008}}
[[Image:Anther01.jpg|thumb|right|[[Strawberry]] anther with parallel thecae]]
A '''theca''' (plural thecae) refers to any case, covering, or sheath.
In '''[[botany]]''', the theca of an [[angiosperm]] is half of the [[anther]]. An anther and its filament form together a typical (or filantherous) [[stamen]], part of the male [[flower|floral]] organ.
Each anther is bilocular, i.e. it consists of two thecae. Each theca contains two [[pollen]] sacs (the male [[sporangium]] with the microspores).
The tissue between the locules and the cells is called the [[connective]] and the [[parenchyma]]. Both pollen sacs are separated by the [[stomium]]. When the anther is dehiscing, it opens at the stomium.
The outer cells of the theca form the [[Epidermis (botany)|epidermis]]. Below the epidermis, the [[somatic]] cells form the [[tapetum (botany)|tapetum]]. These support the development of [[microspore]]s into mature pollen grains. However, little is known about the underlying genetic mechanisms, which play a role in male sporo- and gametogenesis.
The thecal arrangement of a typical stamen can be as follows :
* divergent : both thecae in line, and forming an acute angle with the filament
* transverse (or explanate) : both thecae exactly in line, at right angles with the filament
* oblique: the thecae fixed to each other in an oblique way
* parallel : the thecae fixed to each other in a parallel way
[[Category:Plant physiology]]
[[Category:Plant anatomy]]
[[Category:Pollination]]
In '''[[biology]]''', the [[theca of follicle]] can also refer to the site of [[androgen]] production in females.
[[de:Theca]]
[[es:Teca (protista)]]
[[pl:Pylnik]]