a. [mod. f. Gr. τρίμορφ-ος (f. τρι-, TRI- + μορφή form) + -IC.] Having, or existing in, three forms: spec. a. Bot. Having flowers with pistils and stamens of three different relative lengths. b. Zool. Exhibiting three different forms (colorations, etc.) in different individuals of a species, or of a colony of polyps. c. Cryst. Of a substance: Occurring in crystals of three fundamentally different forms with the same chemical composition.
1866. Darwin, Orig. Spec., iv. (ed. 4), 111. The reciprocally dimorphic and trimorphic plants.
1870. Nicholson, Man. Zool., 19. When two such distinct forms exist the species is said to be ‘dimorphic,’ and when three are present it is called trimorphic.
1870. Hooker, Stud. Flora, 147. Lythrum Salicaria … Flowers trimorphic in respect of length of style and filaments in 3 sets of individuals.
1888. Rolleston & Jackson, Anim. Life, 238. The worker bee is a dimorphic female; the soldiers and workers among the Termites are trimorphic with the fully formed male and female.
So Trimorph, Cryst. a trimorphic substance, or each of its three different forms; Trimorphism, trimorphic condition, occurrence in three different forms (of a plant, animal, or crystalline substance); Trimorphous a. = trimorphic.
1860. Worcester, *Trimorphism, the property of crystallizing in three different forms. Dana.
1862. Darwin, in Life & Lett. (1887), III. 301. If I can only prove … it [Lythrum] is a grand case of trimorphism, with three different pollens and three stigmas. Ibid. (1866), Orig. Spec., ii. (ed. 4), 50. There are, however, other cases, namely of dimorphism and trimorphism,… which certain animals of either sex, and certain hermaphrodite plants, habitually present. Thus … the females of certain species of butterflies … appear under two or even three conspicuously distinct forms.
1875. Lubbock, Wild Flowers, iii. 77. Of the foreign species of Oxalis some are dimorphous, some *trimorphous.
1878. Gurney, Crystallogr., 83. Titanium dioxide is trimorphous, for it not only crystallises as Anatase and Rutile, but also as Brookite.
1909. Cent. Dict., Suppl., Trimorph.
