Part 7 - UNC Herbarium

POACEAE 903
3 Panicle branches 7-70, the axes extending beyond the outermost spikelets; panicle branches disarticulating at
maturity...................................................................................................................................................... P. fluitans
3 Panicle branches 1-6, terminating in a spikelet; panicle branches persistent.
4 Upper florets olive to dark brown ............................................................................................P. scrobiculatum
4 Upper florets pale to tan.
5 Axes of panicle branches not broadly winged, 0.6-1.3 mm wide.
6 Spikelets orbicular, 2.8-3.2 mm wide...............................................................P. laeve var. circulare
6 Spikelets slightly longer than broad, 2.0-2.5 mm wide .......................................... P. laeve var. laeve
5 Axes of panicle branches broadly winged, 1.8-3.3 mm wide.
7 Spikelets 3.2-4.0 mm long; upper lemmas with a few short hairs at their tips............ P. acuminatum
7 Spikelets 1.7-2.1 mm long; upper lemmas glabrous........................................................P. dissectum
2 Panicles usually composed of a terminal pair of brancxhes, sometimes with 1 (-5) additional branches below the
terminal pair.
8 Upper glumes pubescent on the back or margins.
9 Spikelets 1.3-1.9 mm long; upper glumes pilose along the margins .........................................[P. conjugatum]
9 Spikelets 2.4-3.2 mm long; upper glumes sparsely pubescent on the back .....................................P. distichum
8 Upper glumes glabrous.
10 Spikelets elliptic, acute or acuminate at the tip ..............................................................................P. vaginatum
10 Spikelets ovate to broadly elliptic, obtuse to broadly acute at the tip.
11 Spikelets 1.9-2.3 mm long; leaf blades flat ................................................................................ [P. minus]
11 Spikelets 2.5-4.0 mm long; leaf blades flast or longitudinally folded ....................................... P. notatum
1 Spikelets paired, or at least the second nonfunctional spikelet represented by a naked pedicel.
12 Spikelets 1.0-1.3 mm long .......................................................................................................................[P. paniculatum]
12 Spikelets 1.3-4.1 mm long
13 Margins of upper glumes and lower lemmas pilose.
14 Panicle branches 2-7; spikelets 2.3-4.0 mm long ............................................................................ P. dilatatum
14 Panicle branches (4-) 10-30; spikelets 1.8-2.8 mm long ..................................................................... P. urvillei
13 Margins of upper glumes and lower lemmas neither ciliate-lacerate, winged, nor pilose (if pubescent, the hairs not
pilose).
15 Upper florets olive to dark brown.
16 Panicle branches 10-28 (or more).
17 Plants annual; axes of panicle branches broadly winged, the wings about as wide as the central
portion; [common native].............................................................................................. P. boscianum
17 Plants perennial; axes of panicle branches narrowly winged, the wings narrower than the central
portion; [rare exotics].
18 Axes of panicle branches 0.5-1.2 mm wide; spikelets 1.1-1.8 mm wide ............. P. conspersum
18 Axes of the panicle branches 1.0-1.7 mm wide; spikelets 1.8-2.4 mm wide ............ P. virgatum
16 Panicle branches 1-10 (or to 28 in P. boscianum, keyed under both leads).
19 Plants annual.
20 Spikelets 1.3-1.8 mm wide, broadly elliptic to orbicular, glabrous; panicles with 1-10 (-28)
branches, the axes 0.7-2.3 mm wide...................................................................... P. boscianum
20 Spikelets 1.7-2.4 mm wide, broadly obovate, shortly pubescent; panicles with 1-5 branches,
the axes 0.8-1.3 mm wide.....................................................................................[P. convexum]
19 Plants perennial.
21 Plants cespitose, rhizomes poorly developed; culms 10-20 dm tall; panicle branches
ascending, divaricate, or reflexed.
22 Leaves 7-18 mm wide.................................................................................. P. conspersum
22 Leaves 2.5-4 mm wide................................................................................... P. plicatulum
21 Plants not cespitose, rhizomatous; culms 1-15 dm tall; panicle branches ascending.
23 Rhizomes long, evident .......................................................................................P. nicorae
23 Rhizomes short, indistinct ............................................................................. P. plicatulum
15 Upper florets white, stramineous, or golden brown.
24 Lower lemmas with well-developed cross-ribs over the veins; upper glumes absent.....P. malacophyllum
24 Lower lemmas not ribbed over the veins; upper glumes present.
25 Panicles with 15-100 branches.
26 Plants annual; upper glumes and lower lemmas rugose..................................... [P. racemosum]
26 Plant perennial; upper glumes and lower lemmas smooth.
27 Plant rhizomatous; panicle branch axes 0.9-1.2 mm wide; panicle branches often arcing...
.................................................................................................................... P. intermedium
27 Plant cespitose; panicle branch axes 0.3-0.6 mm wide; panicle branches straight.
28 Panicle branches spreading to reflexed (rarely ascending); leaf blades 10-23 mm
wide; axes of panicle branches 0.3-0.4 mm wide ................................P. coryphaeum
28 Panicle branches erect to ascending; leaf blades 4.9-6.1 mm wide; axes of panicle
branches 0.5-0.6 mm wide.............................................................. [P. quadrifarium]