from The American Heritage® Dictionary of the English Language, 5th Edition.
- adjective Having or consisting of four similar parts.
- adjective Having flower parts, such as sepals, petals, and stamens, in sets of four.
from The Century Dictionary.
- Consisting of or divided into four parts; characterized by having four parts.
from the GNU version of the Collaborative International Dictionary of English.
- adjective (Bot.) Having the parts arranged in sets of four.
- adjective (Zoöl.) Having four joints in each of the tarsi; -- said of certain insects.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- adjective botany in four parts: in a flower each whorl (of flower parts) has four flower parts.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- adjective having or consisting of four similar parts; tetramerous flowers
from Wiktionary, Creative Commons Attribution/Share-Alike License
= -- An increased number of stamens frequently accompanies the corresponding alterations in other whorls, and seems, if anything, to be more frequent among monocotyledonous plants than among dicotyledonous ones; thus, we occasionally find tetramerous flowers in _Crocus_, _Hyacinthus_, _Tulipa_, _Iris_,
Thus trimerous fuchsias and tetramerous jasmines may frequently be met with, and Turpin describes a tetramerous flower of _Cobæa scandens_.
It is so common to observe on the same plant, flowers indifferently tetramerous, pentamerous, &c., that I need not give examples; but as numerical variations are comparatively rare when the parts are few, I may mention that, according to De Candolle, the flowers of Papaver bracteatum offer either two sepals with four petals (which is the common type with poppies), or three sepals with six petals.
In the common rue and some other plants, one flower, usually the central or terminal one, opens first, and has five sepals and petals, and five divisions to the ovarium; whilst all the other flowers on the plant are tetramerous.
In the British Adoxa the uppermost flower generally has two calyx-lobes with the other organs tetramerous, whilst the surrounding flowers generally have three calyx-lobes with the other organs pentamerous.
Would you not consider as a morphological difference the trimerous, tetramerous, etc., divisions of flowers, the ovules being erect or suspended, their attachment being parietal or placental, and even the shape of the seed when of no service to the plant.
This botanist observed and figured a flower of _Orchis palustris_ with tetramerous arrangement of parts, that is to say there were four outer segments to the perianth, four petals, of which two were lip-like, four stamens, three of which were rudimentary, and an ovary with four parietal placentæ. [