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CPIE Notebook Project - Grasses and Sedges of Hawai‘i Grass Key – Page 2

Canes and Very Large Grasses

In terms of size or height specifically, most grasses range from small (such as grasses in a park lawn) to large and reaching or perhaps a little exceeding a human in height (see definitions on Page iv). Some grasses are much larger, close to 10 feet (large grass) or, in the case of some bamboos, exceeding 70 feet (very large grass). However, some of these grasses may start out modest in size and take years to pass from modest to very large. Some may never reach their potential, depending upon growing conditions. A familiar example is corn, a large grass. However, corn in the backyard garden may never tower over it's gardener, even while producing perfectly delicious fruit. The grasses on this page are typically at the upper end of "large" to "very large", but their gestalt may be in the coarseness of their features as much as in their height.

[CANES AND LARGE GRASSES]

. .
15a (11) Grass large to very large, clumping and without visible stems (not counting flowering culm) [16]
15b

Grass large to very large, clumping or spreading but with leaves arranged along a vertical stem (a reed or cane; or forming dense, nearly impenetrable, clumps)

[18]
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16a (15) Leaves lemon-scented. Inflorescence rarely produced in Hawai‘i. { Grass a tuft to 4 feet high and 4 feet across. Lemon grass. [ORN]
    Cymbopogon citratus (C. Nees) Stapf
16b (15) Leaves NOT lemon-scented. Inflorescence a showy white to purple plume up to 3 feet in length { Grass a tuft to 10 feet high, with long, arching, sharp-edged leaves. [17]
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17a (16) Leaves and culm with an abundance of hairs on sheaths. { Pampas grass. A noxious weed spreading on Maui. [NAT]
    Cortaderia jubata (Carriere) Stapf
17b Leaf and culm sheaths glabrous on outside surfaces. { Pampas grass. [ORN]
    Cortaderia selloana (J.A. & J.H. Schultes) Ascherson & Graebner
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[NOTE: THREE CHOICES HERE]
18a (15) Culm nodes usually hidden by leaf sheaths; culms reed or cane-like, stiff but not woody. Younger leaf blades relatively broad (length may be less than 10x width), but older blades linear

[19]
18b Culm nodes usually hidden by leaf sheaths, culms stiff but not woody. Plant not a cane, but typical grass form, with leaf blades relatively broad and definitely linear. { Forming tall, dense clumps

[23]
18c Culm nodes exposed; culms woody. Leaf blades generally short, not linear. Bamboos.
    ~ Subfamily BAMBUSOIDEAE
[24]
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19a (18) Stems much branched [22]
19b

Cane-like stems usually unbranched; if clumping and multiple stemmed, the stems are suckers growing up from base

[20]
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20a (19) Annual or perennial, reedlike herb with a solid (not hollow)stem. [21]
20b

Arundo donaxPerennial reed with hollow stem, usually unbranched. Leaf margins wavy only at base of blades if at all; blades to 2.4 inches across. Inflorescence an erect oblong panicle with complete florets (both sexes present). Giant reed, Spanish reed (Fig. 2A). [ORN]

    Arundo donax L.


Figure 2A. Small Arundo donax in
abandoned garden in Wai‘anae.

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21a (20) Annual herb. leaves with wavy margins and up to 5 inches across, the sheaths overlapping. Male and female flowers on separate inflorescences: male spikelets on a terminal panicle; female spikelets on spikes produced in the leaf axils, producing long pistils (silk) and edible fruit. Corn, kūlina. [ORN]
    Zea mays L.
21b

Perennial, clump-forming reed. Each stem section with root buds around base. Leaf blades to 2.5 inches wide; sheaths overlapping. Blades mostly glabrous, but with tufts of long hairs at collar. Ligule a membrane topped with short hairs and a row of stiff hairs behind ligule. Inflorescence a large, terminal plume. Sugar cane, [ORN].

    Saccharum officinarum L. or a hybrid/cultigen
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22a (19) Leaves deep green, typically broad and wavy. Inflorescences numerous at top and from axils and unusual in having "seed-like" white to gray cupule structures supporting pistillate and staminate racemes. { a robust annual growing to nearly 10 ft in and along the margins of streams and other wet areas. Job's tears, pū‘ohe‘ohe. [NAT]
    Coix lachryma-jobi L.
22b Leaves deep purple to reddish bronze. Inflorescence a purplish foxtail. { Smaller clumps look like fountain grass but larger plants (to 10 feet) are cane-like. Burgandy fountain grass. [ORN]
    Cenchrus caninus (Reinw. ex Blume) Marrone
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23a (18) Inflorescence a long, yellow foxtail. Leaves with prominent, white midrib, glabrous (not hairy) or with long hairs at margins near collar; ligule a thin membrane topped with tight packed hairs. { Grass forming impenetrable, close-set clumps in mesic to wet areas, particularly near streams. Elephant grass, Napier grass. [NAT]
    Cenchrus purpureus (Schumach.) Marrone

23b Inforescence an open, much branched panicle. Leaf blades on mature plants up to 1 in (3 cm) across. { An extremely common, clumping grass in lowland disturbed areas and abandoned pastures in mesic and wet areas. Stems have stiff hairs that cause itching as hairs detach and irritate the skin. Guinea grass. [NAT]
    Megathyrsus maximus (Jacq.) B.K. Simon & W.L. Jacobs


Synonyms for grasses on this page:

    Panicum maximum Jacq. (= Megathyrsus maximus)
    Pennisetum macrostachyum (Brong.) Trinius (=Cenchrus caninus)
    P. purpureum Schumach.(= C. purpureus)
    Urochloa maxima (Jacq.) Webster (= Megathyrsus maximus)

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