The present study is part of a comparative investigation on floral structure and development of basal orchids and potential sister groups. Based on molecular analyses Hypoxidaceae are among the proposed sister groups to orchids (Chase et al.). Floral structure and development of two species of Curculigo (C. capitulata and C. latifolia) were studied. Although anthetic flowers are polysymmetric, they have a monosymmetric phase in early development. Each flower forms in the axil of a large bract, which protects it during early development. Flower development begins with a transversally broadened bulge. The first visible organ primordia are the two lateral outer tepals, while the median outer tepal is delayed. However, the inner tepals are equal from the beginning. The stamens develop from common primordia with outer and inner tepals. In C. capitulata the anthers unite postgenitally before anthesis. Pollen is released from the tube of the united anthers through two apical openings of each anther. The nectar-less flowers are of the Solanum type and are probably buzz-pollinated. In C. latifolia the anthers remain free and pollen is released by two longitudinal slits from each anther. The gynoecium has an inferior trilocular ovary with numerous ovules; the stigma is dry and papillate. Flower structure and development considerably resembles that of basal orchids (Apostasioideae), and may support a close relationship between Hypoxidaceae and Orchidaceae (work in progress).

Key words: Apostasioideae, Curculigo, development, flowers, Hypoxidaceae, Orchidaceae