Family: Poaceae |
Mary E. Barkworth Plants perennial, rarely annual; cespitose, loosely tufted, or mat-forming, sometimes rhizomatous or stoloniferous. Culms 7-300 cm, not woody, often decumbent at the base, erect to ascending. Sheaths open; ligules membranous, truncate, ciliate; blades flat or convolute, usually obtuse. Inflorescences terminal, sometimes also axillary, panicles of 2-many, digitately, subdigitately, or racemosely arranged spikelike branches; branches triquetrous, spikelets subsessile or sessile, solitary, in 2 rows, lower lemmas appressed to the branch axes; disarticulation below the glumes. Spikelets dorsally compressed, with 2 florets; lower florets sterile or staminate; upper florets sessile, bisexual. Lower glumes absent; upper glumes and lower lemmasequal, membranous; lower paleas absent; upper lemmas indurate, usually glabrous, sometimes with an apical tuft of hairs, margins slightly involute, clasping the palea, apices acute to obtuse; upper paleas similar to the upper lemmas in texture. Caryopses ellipsoid. x = 10. Name from the Greek axon, axis, and pes, foot. López & Morrone (2012) expanded Axonopus to include two small genera, Centrochloa and Ophiochloa. They commented that "The spikelet’s orientation [lower lemmas appressed to the branch axes]is the diagnostic character to group Axonopus, Centrochloa, and Ophiochloa in a single genus and differentiates them from other Paniceae". This statement also applies to their differentiation from other members of Paspaleae, a tribe is a segregate of Paniceae and the one to which Axonopus belongs. Black, G.A. 1963. Grasses of the genus Axonopus (a taxonomic treatment) (ed. L.B. Smith). Advancing Frontiers Pl. Sci. 5:1-186. López, A. & O. Morrone. 2012. Phylogenetic Studies in Axonopus (Poaceae, Panicoideae, Paniceae) and Related Genera: Morphology and Molecular (Nuclear and Plastid) Combined Analyses. Systematic Botany 37: 671-676. |