Digitaria Effusa (Gramineae), a new species from Vietnam

During an agrostological survey in the Lam Dong Province, Vietnam, Mr. J.B. Hacker (St. Lucia, Queensland, Australia) collected a remarkable undescribed species of Digitaria. Among the Asian taxa it is peculiar because of its montane provenance coupled with a combination of an inflorescence with well-developed common axis with alternate racemes, the presence of a small lower glume, and the absence of any indument on the spikelet. Somewhat similar is D. wallichiana (Steud.) Stapf, also a montane species occurring with one subspecies in Sri Lanka and Madras, and another in Java and Bali. It differs by the whorled lowermost branches of the inflorescence, the absent lower glume, and a longer upper glume (1.6-2 mm long, 0.8-0.95 times as long as the spikelet), and a usually presence of an indument on the spikelet. The spikelets are surprisingly similar to those of the rare Vietnamese species Panicum amoenum Balansa and P. smithii M.M. Rahman, but these have a much larger habit with larger inflorescences, long-pedicelled spikelets, large and nerved lower glumes, and an indurated fertile lemma in fruit. Hacker’s specimens do not have mature fruits, but the paired spikelets with short and somewhat longer pedicels are typical for binate Digitaria species and not for a Panicum.