Panicum dichotomiflorum Michx.

Family: Poaceae, Tribe: Paniceae

Pertinent Synonyms & Notes (particularly those used in California; go to GRIN for other synonyms)

probably only ssp. dichotomiflorum occurs in California

Pertinent Common Names (particularly those used in California; go to GRIN for other common names)

smooth witchgrass, fall panicgrass

Primary Disseminule Type

spikelet, floret

Description (diagnostics are in brown)

Spikelets solitary, pedicelled, narrowly elliptic-oblong to ovate, dorsally compressed, 1.8–3.8 mm long x 1–2 mm wide x 0.9–1 mm thick, light green or purplish, glabrous, apex acuminate, consisting of one basal sterile floret and one fertile floret without rachilla extension. Disarticulation at base of each spikelet.

Glumes ovate, dissimilar, reaching apex of florets, thinner than fertile lemma, membranous to subcoriaceous, without keels. Lower glume 0.5–1.2 mm long (0.2–0.33 length of spikelet), enwrapping base of spikelet, (0)1–3(5)-veined, apex truncate or obtuse to acute. Upper glume same length as spikelet, 7–9-veined, apex acute.

Sterile lemma similar to upper glume (ovate, same length as spikelet, membranous to subcoriaceous, 7–9-veined), extending beyond the upper fertile floret by 0.3–0.6, apex acute. Sterile palea vestigial to almost as long as sterile lemma, 2-veined, veins glabrous.

Fertile floret held loosely by outer bracts and ± exposed at maturity. Fertile lemma elliptic, dorsally compressed, (1.4)1.8–2.2(3) mm long, indurate, without keel, straw-colored to very dark brown with pale veins, shiny, glabrous, surface faintly striolate, margins involute, apex acute. Fertile palea indurate, margins involute.

Caryopsis broadly elliptic or oblong to ovate, ca. 1.5 mm long x ca. 0.8 mm wide, light brown, embryo 0.4–0.5 length of caryopsis, hilum round to oval.

Similar Species

Similar Species Comparison Chart

Risk Assessment (codes in yellow or red indicate cause for concern; assessments are current as of mid-2011; click AUQP, NZBORIC, or NZBPI for access to the most recent versions of these databases and possible assessment changes)