In: Phyton, 51 Fasc. 2 (2011), S. 315-327, with 3 figures

Key words: Anaxagorea dolichocarpa, Annonaceae. Colopterus, Nitidulidae. – Cantharophily, continuous flowering, dichogamy, thermogenesis. – Flora of N South America.

Summary

BRAUN M. & GOTTSBERGER G. 2011. Floral biology and breeding system of Anaxagorea dolichocarpa (Annonaceae), with observations on the interval between anthesis and fruit formation. – Phyton (Horn, Austria) 51(2): 315–327, with 3 figures.

Floral biology, phenology, and fruit set of Anaxagorea dolichocarpa SPRAGUE & SANDWITH (Annonaceae) was studied in the Atlantic forest in Northeast Brazil. Herein, the thick petals form a floral chamber, which is accessible only to small insects. Flowers are protogynous, without overlap between the carpellate and the staminate phase. The anthesis starts in the afternoon (14.00–15.00 h), and the carpellate phase lasts until late morning of the next day. Pollen is released in the early af-ternoon (12.00–13.00 h) on the second day of flowering. The staminate phase ends between 14.45 and 15.45 h with the opening and shedding of the petals, which overlapped with the beginning of the carpellate phase of the next days‘ flowers. Both the carpellate and the staminate phase are ac-companied by strong fruity scent and thermogenesis of up to 3.8 °C (carpellate) and 3.7 °C (stami-nate phase) above ambient temperature. Experiments showed that A. dolichocarpa is self-compatible, but pollinator-dependent for fruit set. Although stingless bees (Trigona sp.) regularly visit staminate phase flowers for pollen at the end of anthesis, only small nitidulid beetles (Colop-terus spp.) were recorded as pollinators. They enter the floral chamber during the first hours of anthesis, feed on pollen during the staminate phase, and stay until the petals shed. Flowering is con-tinuous and trees produce few flowers at a time. The beginning of visible fruit growth was delayed for a rather long period of up to nine months, varying strongly among single flowers. Seeds are dis-persed by an autochorous mechanism.