GrassBase - The Online World Grass Flora


W.D. Clayton, M. Vorontsova, K.T. Harman & H. Williamson

© Copyright The Board of Trustees, Royal Botanic Gardens, Kew.

Panicum irregulare

HABIT Perennial. Culms decumbent, or prostrate; 20–50 cm long; 1–1.5 mm diam.; rooting from lower nodes. Leaf-sheaths glabrous on surface. Leaf-sheath oral hairs scanty. Leaf-sheath auricles erect. Ligule a fringe of hairs. Leaf-blade base asymmetrical; with a brief petiole-like connection to sheath; petiole 0.1 cm long; petiole pubescent. Leaf-blades lanceolate; 4.5–7 cm long; 9–15 mm wide.

INFLORESCENCE Inflorescence composed of racemes. Peduncle 5–15 cm long.

Racemes 10–15; borne along a central axis; drooping; unilateral; 1–2 cm long. Central inflorescence axis 16–24 cm long.

Spikelets in pairs. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 2 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; 1.7–2.2 mm long; falling entire; readily shedding fertile florets.

GLUMES Glumes dissimilar; reaching apex of florets; thinner than fertile lemma. Lower glume ovate; 1 mm long; 0.33–0.5 length of spikelet; membranous; without keels; 3 -veined. Lower glume apex acute. Upper glume ovate; 2 mm long; 1 length of spikelet; membranous; without keels; 5 -veined. Upper glume apex acute.

FLORETS Fertile florets with the lowest dissimilar. Lowest fertile lemma bisexual; ovate; 2.2 mm long; 1.6 length of adjacent lemma; thinner than adjacent lemma (membranous). Fertile lemma ovate; dorsally compressed; 1.4 mm long; indurate; shiny; without keel. Lemma margins involute. Lemma apex acute. Palea involute; indurate.

FLOWER Anthers 3; 1.1–1.2 mm long; brown.

DISTRIBUTION South America: Mesoamericana.

NOTES Paniceae. Fl Costa Rica 1994.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.