Pak. J. Bot., 47(3): 959-965, 2015.

FLORAL ONTOGENY OF TWO JATROPHA SPECIES (EUPHORBIACEAE S.S) AND ITS SYSTEMATIC IMPLICATIONS

HUANFANG LIU1*, SHULING LIN2 AND JINGPING LIAO1

Abstract: Floral ontogeny of Jatropha multifida L. and Jatropha integerrima Jacq. (Euphorbiaceae) was studied using scanning electron microscopy (SEM). These two species possess unisexual male flowers and bisexual (with unfunctional staminodes) female flowers. In both male and female flowers, five sepal primordia arise in a 2/5 sequence on the periphery of the floral apex and initiate anticlockwise or clockwise in different floral buds. Five petal primordia initiate simultaneously alternate to sepals. Dicyclic stamens (obdiplostemony) arise in both male and female flowers. In J. multifida, five outer stamen primordia arise first simultaneously and then three inner stamens initiate simultaneously. However, in J. integerrima, ten stamen primordia arranged in two whorls initiate simultaneously. While the ovary is absent in the male flowers, in the female flowers, three carpel primordia appear simultaneously. With further development of the ovary the stamens degenerate in the female flowers, whereas in the male flowers, the stamens grow normally. Ancestral state reconstruction using MacClade indicates that stamen simultaneous vs. non-simultaneous initiation supports the phylogenetic analysis based on nuclear ribosomal DNA ITS sequence.

Key words: Floral ontogeny, Jatropha multifida, Jatropha integerrima, Systematic implications.

1 Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China

2 School of Geographical Sciences, Guangzhou University, Guangzhou 510006, China

Corresponding author’s e-mail: hfliu@scbg.ac.cn