The Genus Bolboschoenus PALLA in Japan

Abstract

Nomenclatural identity has been established for the three Far Eastern species of Bolboschoenus that I recognize as valid. They are B. fluviatilis ssp. yagara (n. comb.), B. maritimus and B. planiculmis, which may be differentiated by the following key. A) Achenes truly trigonous, rhombic-obovate, subacute at apex; stigmas 3; inflorescence an open anthela bearing several to 20 spikelets on several elongated rays. 1. B. fluviatilis ssp. yagara. A) Achenes lenticular (or rarely obcompressed-trigonous with obscurely angular dorsal side), obovate, rounded to mucronate apex; stigmas 2 (rarely 3) ; inflorescence frequently capitate bearing 1 to several spikelets, occasionally developing 1 to few rays. B) Leaf blades dorsi-ventrally flattened ; inflorescence truly terminal, bearing few to several spikelets ; leafy bracts spreading ; hypogynous bristles 2 to 4 (rarely to 6). 2. B. maritimus. B) Leaf blades 3-sided ; inflorescence quasi-lateral, mostly of a single spikelet, rarely with few digitate spikelets ; the lowest bract culm-like, erect ; hypogynous bristles 5 to 6. 3. B. planiculmis.