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Published In: Bulletin of the Torrey Botanical Club 32(11): 604–605. 1905. (Bull. Torrey Bot. Club) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 8/28/2009)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Native


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5. Poa interior Rydb. (inland bluegrass)

Pl. 179 a, b; Map 729

Plants perennial, without rhizomes, forming tufts. Flowering stems 25–80 cm long, erect, sometimes spreading at the very base, circular in cross‑section, glabrous. Leaf sheaths rounded, glabrous, the ligule 0.6–2.0 mm long, rounded to truncate on the margin. Leaf blades 2–20 cm long, 1–2 mm wide, flat or rarely with the margins loosely inrolled, glabrous. Inflorescences 5–15 cm long, open, the lowermost nodes with (2)3–5 branches, these loosely ascending. Spikelets 2.2–4.5 mm long, with 2–4 fertile florets. Lower glume 1.5–3.0 mm long, lanceolate to narrowly ovate, sharply pointed at the tip, with broad, thin margins, 1‑ or 3‑nerved, roughened along the midnerve. Upper glume 1.8–3.2 mm long, narrowly ovate, sharply pointed at the tip, with broad, thin margins, 3‑nerved, roughened along the midnerve. Lemmas 2.0–3.2 mm long, elliptic, sharply pointed at the tip, 3‑nerved (an additional, very faint pair of lateral nerves sometimes present), short‑hairy along the nerves and with a tuft of long, cobwebby hairs at the base. Anthers 0.9–1.6 mm long. Fruits 1.3–2.5 mm long, reddish brown. 2n=28, 34, 42, 43, 56. May–June.

Known from a single specimen from Cass County (western U.S. across the northern Great Plains to Michigan and Vermont; Canada). Upland prairies.

In his initial report of this species for Missouri, Tim Smith (1988) noted that there is some doubt whether P. interior is native at the site that he discovered, because a railroad crosses the property and a number of exotic species occur in the prairie. Also, the main range of the species is not particularly close to Cass County, with the closest stations in western Nebraska. However, P. interior is not generally considered a weedy species in the floristic literature, and the plants were not growing particularly close to the railroad at the Missouri site. Thus, pending further inventory of surrounding sites and more study of the existing population, Smith’s (1988) report is treated here as a native occurrence.



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