Reproductive ecology of Allmania nodiflora, Celosia argentea var. margaritacea, and Digera muricata (Amaranthaceae)

Allmania nodiflora, Celosia argentea var. margaritacea, and Digera muricata are annual herbaceous weeds which reproduce exclusively by seed. The plants appear in June, while flowering time is August-February in agricultural fields and August-October/November in other habitats. The synflorescence is an elongated erect spike in A. nodiflora and C. argentea, while it is a long pedunculate spicate raceme in D. muricata. The flowers anthese acropetally in A. nodiflora and C. argentea var. margaritacea, while there is no such clear-cut anthesis pattern in D. muricata. Allmania nodiflora is functionally hermaphroditic. Digera muricata is partially hermaphroditic because the central flower in three-flowered groups is fertile, while the lateral flowers are sterile. Celosia argentea var. margaritacea is functionally gynodioecious. In A. nodiflora and D. muricata, the flowers facilitate autonomous selfing due to synchrony in maturation of the male and female sex. In C. argentea var. margaritacea also, the flowers facilitate autonomous selfing, but it is precluded by strong protandry. All three species are anemophilous and entomophilous. Allmania nodiflora and D. muricata produce one-seeded fruits, while C. argentea var. margaritacea produces multi-seeded fruits. Allmania nodiflora and C. argentea var. margaritacea dehisce by means of a circumscissile lid and disperse seeds, while D. muricata produces indehiscent fruits. All three species are anemochorous, but A. nodiflora is also myrmecochorous.