Biosystematic studies of selected Texas species of Dichanthelium (Poaceae)

Abstract

A taxonomic study was made of two genera, Dichanthelium and Panicum, in order to justify the elevation of Dichanthelium to generic rank. A comparison of all published characters, all new character differences found by the author, and ecological (including phenological) differences support the rank of genus for Dichanthelium. Dichanthelium and Panicum have as many, if not more, differences than do other closely related genera, i.e., Brachiaria, Paspalum, Eriochloa, and Leptoloma. Although closely related, Dichanthelium and Panicum are distinct genera. Diagnostic characters of selected Texas species of Dichanthelium compared include ligules, leaf blade epidermis, lemma and palea apices, leaf and culm anatomy, and cytology. The selected species include Dichanthelium dichotomum (L.) Gould, D. lindheimeri (Nash) Gould, D. angustifolium (E ll.) Gould, D. lanuginosum (E ll.) Gould, D. oligosanthes (Schult.) Gould, and D. sphaerocarpon (E ll.) Gould. These species were chosen because they are apparently closely related and representative of their respective groups. All are in the subgenus Dichanthelium, but all are in different groups (Brown & Smith, 1975): Dichanthelium dichotomum in group Dichotoma, D. lindheimeri in Spreta, D. angustifolium in Angustifolia, D. lanuginosum in Lanuginosa, D. oligosanthes in Oligosanthia, and D. sphaerocarpon in Sphaerocarpa..