Dicēcious

Dicēcious (Gr. dis, 'twice;' and oikos, 'a habitation'), a term applied by Linnæus to plants in which separate individuals exclusively produce male and female flowers respectively. Great importance was attached to this in the artificial system of classification; but dicacious species occur in all groups of plants indifferently, however commonly hermaphrodite; and similarly, hermaphrodite forms occur in groups usually dicacious. This is probably explained by regarding the complete separation of the sexes as a phase of evolution beyond hermaphroditism which tends to arise in plants as in animals, and from which reversion to hermaphroditism may also readily occur, probably in conditions favourable to vegetativeness (see SEX, REPRODUCTION). Familiar examples of dicacious plants may be seen in most species of willow, or in the pink or white Lychnis (L. diurna and L. vespertina), or the Common Nettle (Urtica dioica). Amongst cultivated plants, hemp, spinach, and the date-palm may be instanced.