Notes on the Genus Paspalum (Poaceae) in the Ryukyu Islands, Japan

Abstract

A new variety, Paspalum scrobiculatum subsp. scrobiculatum var. iriomotense Ibaragi, Yokota & Akai (Poaceae), is described from Iriomotejima Island, the Ryukyu Islands in Okinawa Prefecture, Japan. This new variety has apparently larger spikelets than the other varieties, and resembles P. thunbergii Kunth ex Steud. in having hairy leaf blades and sheaths. However, it differs in its habitat, and also by having two sub-conjugate racemes, being conspicuously rugose on the lemma of the lower floret, and by having fewer tufted culms. Although P. scrobiculatum var. commersonii (Lam.) Stapf is similar to this new variety, var. commersonii differs in some characteristics, e.g., the latter has two or more racemes with small spikelets about 2 mm long. Photo plates of this new taxon and a key to Japanese species of this genus are provided to facilitate its proper identification.