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1. The protective cap or hood covering the spore case of a moss or related plant.
2. A similar hoodlike or caplike structure, such as a root cap.

[Medieval Latin, from Greek kaluptra, veil, from kaluptein, to cover; see kel- in Indo-European roots.]

ca·lyp′trate′ (-trāt′) adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


1. (Botany) a membranous hood covering the spore-bearing capsule of mosses and liverworts
2. (Botany) any hoodlike structure, such as a root cap
[C18: from New Latin, from Greek kaluptra hood, from kaluptein to cover]
calyptrate adj
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(kəˈlɪp trə)

n., pl. -tras.
1. a hood or hoodlike part, as the lid of the capsule in mosses.
2. a root cap.
[1745–55; < New Latin < Greek kalýptra veil, covering]
ca•lyp′trate (-treɪt) adj.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.calyptra - the hood or cap covering the calyx of certain plants: e.g., the California poppycalyptra - the hood or cap covering the calyx of certain plants: e.g., the California poppy
plant part, plant structure - any part of a plant or fungus
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
62 Calyptra derived from the last one or two bracteate organs below the flower (0) absent, (1) present.
Skin-piercing blood-sucking moths III: Feeding act and piercing mechanism of Calyptra eustrigata (Hmps.) (Lepidoptera: Noctuidae).
The fact that the stigmata were receptive and the opening of anthers occurred before the calyptra fall shows cleistogamy, a form of self-pollination reported in other species (MULLINS et al., 1992).
calyptra In mosses, a thin membrane protecting the developing sporophyte and forming a hood over the sporangium (structure containing spores).
A typical tissue organization was observed in the root apex of both adventitious and embryonic roots with a meristematic zone covered by a well-developed calyptra, followed in basipetal direction by elongation zone in which stele, cortex, and epidermis were clearly distinguishable (Figures 4(a) and 4(b)).
This is often around 50-60 days after flowering (when at least 75% of the florets in the cluster have shed the little caps known as "calyptra"), depending on variety and location.