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Related to trimerous: tetramerous


1. Having three similar segments or parts.
2. Botany Having flower parts, such as petals, sepals, and stamens, in sets of three.

trim′er·y n.
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) (of plants) having parts arranged in groups of three
2. (Zoology) consisting of or having three parts
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈtrɪm ər əs)

1. (of flowers) having members in each whorl in groups of three.
2. (of arthropods) having three segments or parts.
[1820–30; < New Latin trimerus; see trimer, -ous]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
References in periodicals archive ?
Because the perianth is trimerous in Hedyosmum and the reconstructed common ancestor of mesangiosperms (Doyle & Endress, 2011; Sauquet et al., 2017).
As an evolutionary old family the Annonaceae exhibit floral morphological characters which they partly share with other representatives of the order Magnoliales and further basal angiosperms, such as hermaphrodititic flowers, a usually trimerous perianth, and numerous stamens and carpels with a helical arrangement along an elongated, mostly convex receptacle.
The pistillate flowers are cream in color, pyramidal, asymmetrical and trimerous, 4.92 to 7.24 mm in length and 4.44 to 6.09 mm in width (Table 2).
Staminate flower symmetrical, trimerous, from barely to widely open at anthesis; sepals 3 short, [+ or -]triangular, sometimes basally connate; petals 3, much exceeding the sepals, valvate, boat-shaped, straight or reflexed, basally connate; stamens 3-12, anthers small, [+ or -]oval-linear, versatile, latrorse; pistillode present, minute, trifid, or absent.
Abbe (1935, 1974) studied floral vasculatures of all genera of Betulaceae and concluded that the ancestral inflorescences of Betulaceae were compound spikes consisting of cymes each with three flowers and the most primitive flowers are bisexual and trimerous with tricarpellary ovaries.