Panicum aquaticum

HABIT Annual. Culms erect, or geniculately ascending; 25–200 cm long. Culm-internodes distally glabrous. Culm-nodes glabrous. Lateral branches lacking, or sparse; arising from lower culm. Leaf-sheaths glabrous on surface, or pilose; with tubercle-based hairs. Ligule a ciliate membrane; 0.6–1.7 mm long. Leaf-blades 6–30 cm long; 4–8 mm wide. Leaf-blade surface glabrous; hairless throughout, or except near base.

INFLORESCENCE Inflorescence a panicle; terminal and axillary.

Panicle open; ovate; 4–27 cm long. Primary panicle branches ascending; 1 -nate; 2.5–13 cm long. Panicle axis scaberulous.

Spikelets appressed; solitary, or in pairs. Fertile spikelets pedicelled; 1–2 in the cluster. Pedicels unequal.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets lanceolate, or elliptic; dorsally compressed; acute; 2.8–3.4 mm long; falling entire.

GLUMES Glumes reaching apex of florets; thinner than fertile lemma. Lower glume ovate; clasping; 1–1.5 mm long; 0.4–0.5 length of spikelet; membranous; without keels; 1–3 -veined. Lower glume apex obtuse, or acute. Upper glume ovate; 1 length of spikelet; membranous; without keels; 7–9 -veined. Upper glume apex acute.

FLORETS Basal sterile florets male; with palea. Lemma of lower sterile floret similar to upper glume; ovate; 1 length of spikelet; membranous; 9 -veined; acute. Palea of lower sterile floret 1 length of lemma. Fertile lemma elliptic; dorsally compressed; 2.2–2.3 mm long; 0.9–1 mm wide; indurate; shiny; without keel. Lemma margins involute. Lemma apex acute. Palea involute; indurate.

FLOWER Anthers 3; 1.2–1.6 mm long.

FRUIT Caryopsis with adherent pericarp.

DISTRIBUTION North America: Mexico. South America: Mesoamericana, Caribbean, northern South America, Brazil, and southern South America.

NOTES Paniceae. Fl Meso-Amer 2004.

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