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adj. Botany
Growing straight, so that the micropyle is at the end opposite the stalk. Used of an ovule.
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.


(Botany) (of a plant ovule) growing straight during development so that the micropyle is at the apex. Compare anatropous
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ɔrˈθɒ trə pəs)

(of an ovule) straight and symmetrical, with the chalaza at the evident base and the micropyle at the opposite extremity.
[1820–30; < New Latin orthotropus]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Adj.1.orthotropous - (of a plant ovule) completely straight with the micropyle at the apex
plant life, flora, plant - (botany) a living organism lacking the power of locomotion
campylotropous - (of a plant ovule) curved with the micropyle near the base almost touching its stalk
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
When Endress and Doyle (2009) added Ceratophyllum to a revised version of this morphological data set, with other taxa constrained to an arrangement based mainly on Doyle and Endress (2000), Ceratophyllum and Chloranthaceae formed a clade supported by five synapomorphies: sessile flowers, one stamen, embedded pollen sacs, one carpel, and orthotropous ovule.
Gymnosperm ovules are always unitegmic and also orthotropous so that the podocarp ovule may be seen as anticipating the anatropous ovule of flowering plants, the second integument being responsible for the necessary asymmetric growth.
Xyridoideae (Xyris) were circumscribed with unifacial leaves; ellipsoid, sulcate pollen; orthotropous ovules; and ellipsoid seeds (Dahlgren et al., 1985; Kral, 1998).