from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The protective cap or hood covering the spore case of a moss or related plant.
- n. A similar hoodlike, lidlike, or caplike structure, such as a root cap.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. In bryophytes, a thin, hood-like tissue that forms from the archegonium and covers the developing sporophyte.
from the GNU version of the Collaborative International Dictionary of English
- n. A little hood or veil, resembling an extinguisher in form and position, covering each of the small flasklike capsules which contain the spores of mosses; also, any similar covering body.
from The Century Dictionary and Cyclopedia
- n. A hood; a covering; a lid.
- n. [capitalized] In zoology: Same as Calyptræa.
- n. A genus of lepidopterous insects.
- n. A genus of cœlenterates.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the hood or cap covering the calyx of certain plants: e.g., the California poppy
A case in which the future organs of reproduction are developed; and here is a most curious circumstance, namely, that though the calyptra, which is a genuine pistillum containing an _ovulum_, becomes torn up from its base, yet it remains in contact with that part of the seta in which the sporules are developed until these make their appearance, or even later!! so that one might as well deny a pistillum to a Reseda, or Leontice, as deny it to these plants on the strength of its being torn from its attachments.
The spore-bearing generation consists of a long stalk, closely held below by the cells of the base of the archegonium; this supports a broadened portion which contains the spores, and the top is covered with the remains of the neck of the archegonium forming the calyptra.
_C_, young capsule of hairy-cap moss (_Polytrichum_), covered by the large, hairy calyptra.
_D_, capsules of _Bartramia_: i, with; ii, without the calyptra.
The terminal cell is always solitary, very often attached to the one next it, which is generally single, obliquely placed, occasionally looking like the dimidiate calyptra capping a young seta.
The sporogonium when nearly mature bursts the calyptra irregularly.
It remains for long enclosed within the calyptra formed by the further development of the archegonial wall and surmounted by the neck of the archegonium.
The upper portion of the archegonial wall is carried up as a calyptra on the sporogonium, which, as in _Sphagnum_, has no seta and is raised on a pseudopodium.
_ Longitudinal section of the summit of a shoot bearing a nearly mature sporogonium, sg, still enclosed in the calyptra; ar ', archegonia which have remained unfertilized; st, stem; b, leaf; p, perianth.
The young sporogonium is protected by a thick calyptra derived from the tissue of the thallus around the archegonium.