Pump mechanism, secondary pollen presentation, psychophily and anemochory in Emilia sonchifolia (L.) DC. (Asteraceae)

Pump mechanism, Psychophily and Anemochory in Emilia sonchifolia.

Abstract

Emilia sonchifolia flowers profusely during August-November. The plant produces capitulum inflorescence with only disc florets presenting nectar and pollen as rewards.  It is temporally dioecious with strong protandry which prevents autonomous autogamy, minimizes geitonogamy and maximizes xenogamy. The florets exhibit secondary pollen presentation using pump mechanism. The florets produce minute amount of sucrose-rich nectar, and essential and non-essential amino acids. The floral characters typify psychophily but other insects also pollinate the florets. Thrips use this plant as breeding and feeding sites; they largely contribute to geitonogamy.  The high natural fruit and seed set rates recorded indicate that geitonogamy and xenogamy are functional but both modes are essentially vector-mediated. The function of dual modes of breeding suggests that the plant is self-compatible, self- as well as cross-pollinating.  The fruit is typically an achene and is anemochorous.  Seeds germinate only during rainy season and produce new plants within a short time to reproduce sexually. The study suggests that this plant grows in open well drained areas, important as a pioneer species and hence is useful for the restoration of ecologically degraded, damaged and deteriorated habitats.