Panicum xanthophysum

HABIT Perennial; caespitose; clumped loosely. Culms erect, or geniculately ascending; 20–55 cm long. Culm-internodes antrorsely scabrous. Culm-nodes glabrous. Lateral branches ample; arising from mid culm. Leaves heterophyllous with a basal winter rosette. Leaf-sheaths loose; pilose; with tubercle-based hairs; outer margin hairy. Ligule a ciliate membrane; 1 mm long. Leaf-blades erect; lanceolate; 10–15 cm long; 10–20 mm wide. Leaf-blade venation prominent. Leaf-blade surface glabrous. Leaf-blade margins tuberculate-ciliate; hairy at base. Leaf-blade apex acuminate.

INFLORESCENCE Inflorescence a panicle; terminal and axillary.

Panicle open; linear; 5–15 cm long; bearing few spikelets. Primary panicle branches appressed.

Spikelets solitary. Fertile spikelets pedicelled.

FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets obovate; dorsally compressed; compressed slightly; obtuse; 3.7–4 mm long; 2–2.1 mm wide; falling entire.

GLUMES Glumes dissimilar; reaching apex of florets; thinner than fertile lemma. Lower glume lanceolate; 0.5 length of spikelet; membranous; without keels. Lower glume apex acute. Upper glume elliptic; 1 length of spikelet; membranous; without keels; 7 -veined. Upper glume lateral veins prominent. Upper glume surface pubescent. Upper glume apex obtuse.

FLORETS Basal sterile florets barren; with palea, or without significant palea. Lemma of lower sterile floret similar to upper glume; elliptic; 1 length of spikelet; membranous; prominently veined; pubescent; obtuse. Fertile lemma obovate; dorsally compressed; 2.9–3 mm long; 2 mm wide; indurate; without keel. Lemma margins involute. Lemma apex obtuse. Palea involute; indurate.

DISTRIBUTION North America: western Canada, eastern Canada, north-central USA, and northeast USA.

NOTES Paniceae. Chase 1994.

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