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CPIE Notebook Project - Grasses and Sedges of Hawai‘i Grass Key – Page 15

Our most common plumose grasses are:


[PLUMOSE PANICULATE GRASSES]

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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) Broomsedge inflorescences with and without spikelets 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. Broomsedge, yellow bluestem. (Fig. 15A) [NAT]]
    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 and Hawai‘i only. Giant broomsedge, beardgrass. (Fig. 15B and 15C) [NAT]

    Schizachyrium condensatum (Kunth) Nees
Schizachyriuum condensatum habit


Figure 15B. A stand of Schizachyrium condensatum (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. Spikelets not narrow

[92]
91b

Inflorescense a plume-like panicle with racemes typically all leaning or nodding in same general direction. 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. [NAT]

    Digitaria insularis (L.) Mez ex Ekman
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92a (91) Magnifying Lens 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. Natal redtop, Natal grass. (Fig. 15D) [NAT]
    Melinus repens (Willd.) Zizka
92b

Not as above

[93]
      Under Construction Sign


Synonyms for species on this page:

    Rhynchelytrum repens (Willd.) Hubb. (= Melinus repens)
    Tricachne insularis (L.) Nees (= Digiteria insularis)

 

SUPPLEMENTAL PHOTOS
[CLICK ON THUMBNAIL TO OPEN AN ENLARGED IMAGE]

Schizachrium condensatum infloresence Natal redtop inflorescence

Figure 15C. Inflorescence of Schizachyrium condensatum. (2.9 MB).

Figure 15D. Inflorescence of Natal redtop (scan), Melinus repens. (1.3 MB).

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