Definition of "calyptra" []

• The protective cap or hood covering the spore case of a moss or related plant. (noun)
• A similar hoodlike, lidlike, or caplike structure, such as a root cap. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "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."