7. Paspalum pubiflorum Rupr. ex E. Fourn. var. glabrum
Vasey ex Scribn.
Pl. 173
e–g; Map 696
Plants perennial, without rhizomes, forming tufts or clumps.
Flowering stems 40–100 cm long, ascending from usually spreading bases. Leaf
sheaths glabrous or the lowermost ones sparsely hairy, the ligule 0.8–2.5 mm
long. Leaf blades 5–30 cm long, 4–15 mm wide, usually sparsely hairy toward the
base. Inflorescences with the (3–)5–10 spikelike branches mostly more than 2 cm
apart along the main axis. Spikelike branches 4–11 cm long, erect to spreading,
the axis persistent, with a spikelet at the tip, narrow and unwinged, narrower
than the spikelets, the spikelets dense and mostly strongly overlapping along
the axis, mostly paired (from a short, forked stalk) and appearing in 4 rows.
Spikelets 2.8–3.2 mm long, elliptic‑ovate in outline, rounded or bluntly
pointed at the tip. Lower glume absent. Upper glume 2.6–3.2 mm long, elliptic‑ovate,
rounded to bluntly pointed at the tip, 3–7‑nerved, glabrous or nearly so.
Sterile floret with the lemma 2.6–3.2 mm long, elliptic‑ovate, rounded to
bluntly pointed at the tip, (4)5–7‑nerved, glabrous. Fertile floret with
the lemma 2.4–3.0 mm long, elliptic. Anthers 0.8–1.2 mm long. 2n=60.
June–September.
Scattered in the southern two‑thirds of the state (North Carolina to Ohio and Kansas south to Florida and Texas). Upland prairies, bottomland
forests, margins of ponds and lakes, and banks of streams and rivers; also
pastures, fallow fields, crop fields, lawns, ditches, roadsides, railroads, and
moist, open, disturbed areas.
The var. glabrum is a generally northern phase of the
species. The other variety, var. publiflorum, differs in its hairy
spikelets and occurs from Louisiana to Texas, as well as Mexico and Cuba. Steyermark noted that P. publiflorum can be distinguished from Missouri’s other tall species of Paspalum with 4‑rowed spikelets (such as P.
floridanum and P. setaceum) by its stem bases, which are spreading
and tend to root at the lower nodes (vs. erect to ascending the entire length
of the stem).