The Diversity of Pistillate Flowers and Its Taxonomic Value to the Classification of Daphniphyllum (Daphniphyllaceae)

Daphniphyllum is the sole genus of the family Daphniphyllaceae consisting of dioecious species with inconspicuous reduced unisexual mostly caducous flowers. The paucity of helpful taxonomic characters from vegetative and reduced reproductive organs has led to difficulties in intrageneric classification and species identification. The pistillate flowers have characters of higher taxonomic value than those of the vegetative organs, staminate flowers and fruits, but pistillate flower information is rarely reported. Here pistillate flowers of 19 taxa were studied to reveal pistillate floral diversity and major developmental features with a view to intrageneric classification. Four types of stigma shape were recognized: punctiform, reniform, linear and oblong. Daphniphyllum stigmas, except for the punctiform type, elongate variously after an early stage of anthesis. The pistillate flowers of three taxa are asepalus. The calyces of other taxa were categorized into three types, free, cleft and parted, which are consistent within taxa. The existence and persistence of staminodes are diagnostic characters. This study shows that the characteristics of pistillate flowers provide helpful information for identification at the species and even the variety level. Our results do not support the currently accepted two sections, Daphniphyllum and Lunata. Instead, Huang's original intrageneric classification into three sections, Daphniphyllum, Lunata and Staminodia, is supported, but with two species previously in Daphniphyllum reassigned to Staminodia.