Plumose Grasses

	A CPIE Notebook Project – Grasses of Hawai‘i and Guam		Grass Key – Page 15

Our most common plumose grasses are:

Sourgrass [91]—plumose, extremely common medium size grass in Hawai‘i and Guam;
Natal redtop[92]—small grass with a striking red (glossy pink to purple) inflorescence widespread in Hawai‘i and Guam.
Broomsedge [90 ]—Extremely abundant grass on ridges above 150 ft in mesic environments in Hawai‘i;

		[PLUMOSE PANICULATE GRASSES]
89a	(82)	Inflorescence highly branched from middle and upper culm nodes, overall shape broom-like. Racemes arising in the axils of narrow bracts or spathes	[90]
89b		Inflorescence not broom-shaped or weakly so, branching typically off the culm above the leaves; overall shape spindle to ovoid in outline; if somewhat broom-shaped, racemes lax and leaning more or less in unison downwind. Racemes not extending above bracts or spathes	[91]
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90a	(89)	Racemes paired on a stem. { A medium-size, perennial, clumping grass, forming dense stands in open areas in mesic environments, above 150 ft (50 m), especially on O‘ahu and Hawai‘i (Fig. 15A). HDA noxious weed. Broomsedge, yellow bluestem [HAW - NAT] [FACU] Andropogon virginicus L. Figure 15A. Broomsedge grass is characterized by an abundance of silky branches (densely ciliate internodes and pedicels) supporting awned spikelets. These eventuially fall away (inflorescence in foreground, left), the silky quality is lost, leaving a tall, nearly bare, culm.
90b		Raceme single on a stem branch. { A large, perennial, clumping grass, forming dense stands in open areas in mesic environments on Kaua‘i, O‘ahu, and Hawai‘i (Fig. 15B and 15C). HDA noxious weed. Giant broomsedge, beardgrass [HAW - NAT] [FAC] Andropogon tenuispatheus) (Nash) Nash [O‘ahu, and Hawai‘i] Andropogon bicornis L. [Kaua‘i]
		Figure 15B. A stand of Andropogon bicornis (giant broomsedge) at Kapahi, Kaua‘i. For scale, yellow notebook at bottom left is 5 inches across.
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91a	(89)	Inflorescence a small to large plume: an open-panicle with spikelets bearing numerous white to pink or glossy purple bristles, the overall shape from spindle-shaped to narrowly ovoid in outline. Ligule ciliate (dense rim of tall hairs). Spikelets not narrow	[92]
91b		Inflorescense a plume-like panicle with racemes typically all leaning or nodding in same general direction. Ligule a membrane. Narrow, elongated spikelets grouped in twos, threes, or more on long (some branched) pedicels. Rachis narrow, not winged, evenly three-sided. { Very common, medium-size perennial, clumping grass in dry to mesic, disturbed sites. Sourgrass [HAW - NAT] cotton grass, sour grass [GUM - NAT] Digitaria insularis (L.) Mez ex Ekman
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92a	(91)	Bracts enclosing florets (the upper glume and sterile lemma) broad at their base, the basal portion covered with wart-like or bulbous bases of numerous, long silky bristles, these extending well beyond the bracks and redish in color when fresh. Although a small awn may be present, this not easily seen within the bristles. {A small, distinctive, clumping grass: when in flower, the inflorescence is a glossy pink to red color. Widespread, but mostly found in dry, disturbed sites (Fig. 15D). Natal redtop, Natal grass [HAW - NAT] [GUM - NAT] Melinus repens (Willd.) Zizka
92b		Not as above	[93]