from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun The inner tissue of an anther or a moss capsule.
from The Century Dictionary.
- noun In botany: The inner lining of an anther-cell.
- noun In mosses, the central mass of cells in the rudimentary capsule, from which the archespore is generally developed.
from the GNU version of the Collaborative International Dictionary of English.
- noun (Bot.) The inner lining of an anther cell.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun biology The
tissuefound in the walls of anthers, and in moss capsules
from The American Heritage® Dictionary of the English Language, 4th Edition
In _Sphagnum_, as in _Anthoceros_, the archesporium is derived from the amphithecium; in all other mosses it is the outermost layer of the endothecium.
In all other Bryales there is a definite columella extending from the base to the apex of the capsule, the archesporium is derived from the outermost layer of cells of the endothecium, and an air space is formed between the spore-sac and the wall.
The layer of cells immediately around the endothecium becomes the spore-sac, and an air-space forms between this and the wall of the capsule.
The first periclinal division in the region forming the capsule separates an inner group of cells (the endothecium) form the peripheral layer (amphithecium).
The spores are derived from the endothecium, but no distinction of a sterile columella and an archesporium is established in this, a variable number of its cells becoming spore-mother-cells while the rest serve to nourish the spores.