2. Poa bulbosa L. (bulbous bluegrass)
a–c; Map 726
Plants perennial, without rhizomes but with swollen,
somewhat bulblike stem bases, forming tufts. Flowering stems 8–35(–50) cm long,
erect or ascending, circular in cross‑section or slightly flattened,
glabrous. Leaf sheaths rounded, glabrous or minutely hairy, the ligule 1.5–3.5
mm long, rounded on the margin. Leaf blades 2–8 cm long, 1–3 mm wide, flat or
folded, glabrous or minutely hairy. Inflorescences 3–8 cm long, relatively
dense, the lowermost nodes with 2–5 branches, these ascending, roughened.
“Normal” spikelets 3.5–4.5 mm long, with 3–6 florets, but most of the spikelets
with the florets replaced by vegetative bulblets, these 5–25 mm long, with
elongate, linear, pointed tips. Lower glume 1.5–2.2 mm long, narrowly
lanceolate, sharply pointed at the tip, with narrow, thin margins, 1‑nerved,
roughened along the midnerve. Upper glume 1.8–2.4 mm long, narrowly lanceolate,
sharply pointed at the tip, with narrow, thin margins, 1‑nerved,
roughened along the midnerve. Lemmas 1.8–2.6 mm long, elliptic‑lanceolate,
sharply pointed at the tip, faintly 3‑nerved, short‑hairy along the
midnerve and sometimes also the lateral nerves and with a tuft of long,
cobwebby hairs at the base. Anthers 1.0–2.5 mm long. Fruits not produced in Missouri plants. 2n=14, 21, 28, 35, 36, 39, 40, 58. April–May.
Introduced, widely scattered in the state (native of Europe
and Asia, introduced sporadically in the U.S. and adjacent Canada). Lawns, roadsides, sidewalks, and railroads.
In this unusual species, the ovaries of “normal” florets are
shriveled at maturity and do not develop into fruits. Dispersal is by the
vegetative bulblets, which can remain dormant for some time before growing into
plants, and which presumably are spread by a variety of means, including road
graders, mud on shoes and car tires, water, animals, and wind.