Endocarps of menispermaceous plants in Taiwan

Abstract

Background: The fruits of the family Menispermaceae are drupes, and because the drupe endocarps are morphologically diverse, they are generally used to classify members of this family. There is a lack of detailed knowledge of Menispermaceae endocarps in Taiwan. Therefore, in this study, the endocarps of seven genera and 14 species were dissected, and their morphological characters were photographed and described. Furthermore, a key for the 14 species based on the endocarps features, as well as a key of the studied genera, is proposed. Results: The endocarp types comprise a straight shape in Tinospora dentata Diels and a horseshoe shape in the other 13 species. In general, the genus Cyclea bears two dorsal crests with 16 small spines, although there are about 25 spines in Cyclea insularis (Makino) Hatusima. The genus Cocculus has a dorsal convex endocarp with a subannular. In Taiwan, the endocarp of Sinomenium acutum (Thunb.) Rehder & E. H. Wilson has up to 26 transverse ridges, without spines on the crest and might be categorized under the genus Menispermum. Transverse endocarp ridges are found in Stephania cephalantha Hayata and Stephania tetrandra S. Moore, whereas transverse endocarp strips are found in Stephania japonica (Thunb.) Miers, Stephania longa Lour. and Stephania merrillii Diels. Conclusion: We believe that the descriptions and photographs of the endocarp traits of T. dentata, which is endemic to Taiwan, will provide more evidence for further studies on extant and fossil species.