Monographs Details: Siparuna petasiformis Jangoux
Authority: Renner, Susanne S. & Hausner, Gerlinde. 2005. Siparunaceae. Fl. Neotrop. Monogr. 95: 1--247 pp. (Published by NYBG Press)
Description:Species Description - Monoecious tree, 30 m tall, reaching a dbh of 60 cm; young branchlets tetrangular, sparsely covered with minute appressed stellate hairs. Leaves opposite; petioles about 1 cm long; lamina chartaceous, drying brownish, 20-26 X 10-13 cm, the base attenuate, the apex rounded or emarginate, above glabrous, below with sparse minute appressed stellate hairs, with 813 pairs of secondary veins, slightly raised above and below, the margin entire. Cymes 10-12 cm long, with ca. 25 flowers, the indumentum as on the branchlets and lower leaf surfaces, the pedicels with about 12 ridges. Fresh flowers greenish yellow; male flowers urceolate with a flat circular rim, 2-3 mm broad, formed by the fused tepals, adaxially densely pubescent, the floral cup ca. 3 mm high, the indumentum as on the cymes, the flower center depressed, the floral roof forming a rim around the floral pore; stamens 7-9; female flowers similar to the male flowers, the roof raised and closely sheathing the stylar column; styles 3. Mature fruit unknown.

Discussion:Siparuna petasiformis differs from all other species in broad-rimmed flowers (Fig. 31). In habit and leaf shape, S. petasiformis resembles S. pachyantha. However, the leaves are opposite rather than in whorls of 4 to 6 and the indumentum consists of minute ap-pressed stellate hairs while the indumentum of S. pachyantha consists predominantly of peltate scales.
Distribution:Amazonas Brazil South America| Rondônia Brazil South America|