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Published In: Genera Plantarum 1: 44. 1789. (Gen. Pl.) Name publication detail
 

Project Name Data (Last Modified On 7/9/2009)
Acceptance : Accepted
Project Data     (Last Modified On 8/6/2009)

 

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50. Muhlenbergia Schreb. (muhly)

Plants perennial (annual elsewhere), sometimes with rhizomes, forming tufts or less commonly clumps or colonies. Flowering stems erect to ascending or less commonly spreading, glabrous or roughened to short‑hairy. Leaf sheaths rounded on the back or keeled, glabrous or roughened to short‑hairy, the ligule a membrane, this sometimes short and/or uneven to minutely hairy along the margin. Leaf blades flat, folded lengthwise, or with inrolled margins, glabrous or variously roughened or hairy. Inflorescences open to spikelike panicles, terminal or in some species also lateral from the leaf axils, ovate to linear in outline, with spreading or appressed branches. Spikelets with 1 floret (rarely a few spikelets per inflorescence with 2 florets in some species), slightly to moderately flattened laterally, disarticulating above the glumes, the glumes sometimes also shed with age. Glumes about the same length or the lower glume somewhat shorter than the upper glume, the body shorter than to slightly longer than the floret, awnless or awned, 1(–3)‑nerved, rarely nerveless, usually keeled, glabrous or more commonly roughened along the midnerve. Lemma 3‑nerved, the lateral nerves sometimes faint, awnless or awned, rounded on the back, the base glabrous or with a tuft of hairs less than 1/2 as long as the lemma, otherwise glabrous to roughened along the midnerve or short‑hairy. Palea about as long as the lemma, not splitting longitudinally at maturity to expose the fruit. Stamens 3. Fruits linear to narrowly elliptic in outline, reddish brown to dark brown. One hundred twenty‑five to 160 species, nearly worldwide, but mostly in the New World (especially North America).

Many of the species in Missouri belong to a taxonomically difficult complex, most of which is characterized by the production of one to several, prominent, scaly rhizomes, which may reach 10 cm or more in length, and loosely ascending to spreading, strongly 2‑ranked, bluish green to grayish green leaves. This complex was monographed by Pohl (1969), who not only refined the taxonomy, but in doing so altered the limits of some of the species, such that keys in most older floristic manuals no longer work. Observations of the rootstocks of plants are important for proper species determinations in the genus, and collectors should check for the presence of rhizomes when gathering specimens of Muhlenbergia. The 3‑nerved lemmas distinguish Muhlenbergia from all species of Missouri Sporobolus except S. ozarkanus and S. vaginiflorus. In contrast to all Missouri species of Muhlenbergia (which are perennials with at least some of the inflorescences conspicuous and exserted), these two taxa are annuals with the inflorescences all or mostly enclosed within the leaf sheaths at maturity.

 

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1 Inflorescences relatively loose, open panicles, broadly elliptic to ovate in outline, the branches loosely ascending to spreading at maturity; spikelets long-stalked, the stalks mostly several times as long as the spikelet (excluding the awns, if present) (2)
+ Inflorescences dense, spikelike panicles, linear to narrowly elliptic in outline, the branches appressed to the main axis or narrowly ascending; spikelets short-stalked, the stalks less than 2 times as long as the spikelets (excluding the awns, if present) (3)
2 (1) Plants with well-developed rhizomes; lemma 1.1–1.9 mm long, the tip rounded to bluntly pointed and awnless; leaf blades 2–10 cm long, 1–2 mm wide; ligule 0.2–1.0 mm long 1 Muhlenbergia asperifolia
+ Plants without rhizomes; lemma with the body 2.6–5.0 mm long, the tip sharply pointed and with an awn 4–20 mm long; leaf blades 15–35 cm long, (1.5–)2.0–4.0 mm wide; ligule 1.8–8.0 mm long 3 Muhlenbergia capillaris var. capillaris
3 (1) Plants without rhizomes, sometimes knotty at the base, the flowering stems frequently bulbous-thickened or rooting at the lower nodes (4)
+ Plants with well-developed, scaly rhizomes (5)
4 (3) Glumes 0.1–0.4 mm long, both nerveless; lemma with a tuft of short hairs at the base; flowering stems erect or with spreading bases, not bulbous-thickened, but frequently rooting at the lower nodes 9 Muhlenbergia schreberi
+ Glumes 1.5–3.0 mm long, 1-nerved; lemma glabrous at the base; flowering stems erect and often bulbous-thickened at the base, not rooting at the lower nodes 4 Muhlenbergia cuspidata
5 (3) Glumes (including the awns) 4–8 mm long, much longer than the floret 8 Muhlenbergia racemosa
+ Glumes (including the awns, if present) 0.6–5.0 mm long, shorter than to only slightly longer than the floret (6)
6 (5) Lemma glabrous at the base 6 Muhlenbergia glabrifloris
+ Lemma with a tuft of short or long hairs at the base (7)
7 (6) Flowering stems shiny and glabrous between the nodes, the nodes also glabrous (8)
+ Flowering stems dull, roughened to minutely hairy below the nodes (and often elsewhere), the nodes glabrous or minutely hairy (10)
8 (7) Lateral inflorescences absent, or if present then noticeably stalked and not partially enclosed in the subtending leaf sheath; glumes strongly overlapping at the base, the margins curved from about the middle and tapered abruptly to the sharply pointed or short-awned tip 10 Muhlenbergia sobolifera
+ Lateral inflorescences usually abundant, the bases not noticeably stalked, usually partially enclosed in the subtending leaf sheath; glumes only slightly overlapping at the base, the margins relatively straight and tapered gradually from near the base to the sharply pointed or short-awned tip (9)
9 (8) Ligules 0.2–0.7 mm long; glumes 1/2–2/3 as long as the floret 2 Muhlenbergia bushii
+ Ligules 0.7–1.4 mm long; glumes 3/4 as long as to slightly longer than the floret 5 Muhlenbergia frondosa
10 (7) Glumes only slightly overlapping at the base, the margins relatively straight and tapered gradually from near the base to the sharply pointed or short-awned tip (11)
+ Glumes strongly overlapping at the base, the margins curved from about the middle and tapered abruptly to the sharply pointed or short-awned tip (12)
11 (10) Leaf sheaths strongly keeled, the ligule 0.4–1.2 mm long; anthers 0.3–0.5(–0.7) mm long 7 Muhlenbergia mexicana
+ Leaf sheaths rounded to slightly angled on the back, the ligule 1.2–2.6 mm long; anthers (0.4–)0.6–0.9 mm long 11 Muhlenbergia sylvatica
12 (10) Lemmas awnless or rarely with an awn 1–3 mm long; anthers 0.4–0.9 mm long; flowering stems at most roughened just below the nodes; leaf sheaths glabrous 10 Muhlenbergia sobolifera
+ Lemmas with an awn 4–11 mm long; anthers 1.0–2.2 mm long; flowering stems short-hairy between the nodes; leaf sheaths short-hairy 12 Muhlenbergia tenuiflora
 
 
 
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