Systematics of Ruscaceae/Convallariaceae: a combined morphological and molecular investigation

Abstract

This paper discusses the intrafamilial systematics of Ruscaccae sensu lata by means of a combined molecular-morphological analysis. Ruscaceae sensu lata (including former Con-vallariaceae. Dracaenaceae and Nolinaccac, as well as Comospermum and Eriospermum) represent a well-supported clade in other molecular analyses and are further linked by the absence of phytomclan in the seed coat. Within this clade there is an unusual lack of sequence divergence for such a morphologically varied group of taxa, but the combined morphological-molecular analysis indicates some groupings: (1) Eriospermum, (2) Comospermum, (3) nolinoids (former Nolinaceac) plus Ophiopogon and Liriope (Ophiopogonae, excluding Peliosanthes), (4) dracaenoids (former Dracaenaceae), (5; Polygonatae and (6) a clade comprising Convallarieac (including Aspidistra) and the ruscoids (Ruscaccae sensu stricto) plus Peliosanthes. In the morphological analysis Peliosanthes is embedded in Convallarieae, and in the molecular analysis it is sister to all other Ruscaceae except Eriospermum: in neither case does it fall with Ophiopogon and Liriope (Ophiopogonae), with which it was traditionally placed. Peliosanthes has several characters in common with some Convallarieae, e.g. filaments fused into a column surrounding the gynoecium, and a thick, fleshy corona with the stigma more or less filling the narrow floral opening. On the other hand, there arc also some notable differences, such as in karyotype, leaf anatomy, pollen morphology and nectaries. Since there is a considerable range of morphological variation in the taxon currently designated as Peliosanthes. more taxonomic work is needed to establish the monophyly of this genus before there can be confidence in its relationships within Ruscaccae sensu lata.