Floral abnormalities in Jatropha tanjorensis Ellis & Saroja (Euphorbiaceae): a natural interspecific sterile hybrid

Jatropha tanjorensis , an interspecific hybrid between Jatropha curcas and Jatropha gossypifolia , is reported to be a sterile hybrid, which has drastically limited its natural propagation. To determine the probability of existing sterility, floral biology was carried out in 30 trees of six accessions during 2007–2008. The results were explored in terms of morphological and anatomical details of floral abnormality. Although unisex flowers are a characteristic feature of the genus, unusual bisexual flowers with pseudostamens or staminodes were also present. Petalody of the stamen was frequently observed in most of the floral samples. Anther lobes were flat, cordate, fibrous, and some had one or more callus-like structures and contained a few sterile pollen grains. In polypistillody, pistils were irregular in shape and position or were fused with the staminodes. Frequently occurring forms of these floral abnormalities as well as unusual hermaphrodity were highly responsible for the sterility of J. tanjorensis .