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Tribe Andropogoneae
Key to Genus Dichanthium Willemet
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Grasses of the genus, Dichanthium are medium size, clumping grasses that are relatively distinctive in the field with subdigitate racemes and long awns. These grassses are not commonly encountered, although can be abundant where they occur. Racemes typically (1)2 to 6 (or more) in number, sometimes appearing paired. Spikelets are paired, one sessile with an awn and one pedicellate without an awn. These characteristics are shared with species of Bothriochloa. Five species of Dichanthium are recorded from the Hawaiian Islands (Clayton & Snow, 2010; Imada, 2019; Faccenda, 2023) and two or three from Guam (Raulerson, 2016; D. bladhii, not included in this key or in Clayton & Snow); all are introduced species to the islands.
Perennial, tufted (except D. caricosum spreads by rooting at the culm nodes), medium size; ligule membranous; leaves narrow, may be aromatic.
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[GENUS DICHANTHIUM]
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106a
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( 104
&
113) |
Inflorescence of one to 3(6) racemes, these typically paired on erect branchlets with dense hairs (pubescent) ringing the branchlet below each raceme and extending a ways down the common branch or culm. A distinct, short column of dense white hairs occurs at each exposed culm joint. { Naturalized in lawns, pastures, and disturbed sites. Wilder grass [HAW - NAT] [FACU] [GUM - NAT] Dichanthium aristatum (Poir.) Hubb.
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106b
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Branchlet below single or paired racemes hairless (glabrous)
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[107] |
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107a
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Glumes with long hairs (1–4 mm), concentrated towards edges; lower glume typically oblong or obovate, apex blunt, obtuse, or rounded .. .
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[108] |
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107b
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Glumes glabrous with some hairs present OR pilose (having short dense hairs) .. .
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[109] |
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108a
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[107] |
Inflorescence of (1)2 - 5 racemes. Lower glume of sessile spikelet conspicuous (purple if fresh) with long (ciliate) hairs on border forming a subapical arch, hairs partially obscuring spikelets. Australian bluestem. [HAW - NAT]
Dichanthium sericeum (R. Br.) A. Camus
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108b
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Inflorescence of one to (1)2 to 15 racemes. Lower glume of sessile spikelet narrow oblong, with sparse hairs along margin above the middle; some glume hairs papillose-based. [HAW - NAT] [FACU]
Dichanthium annulatum var. papillosum
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109a
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[107] |
Apex of lower glume acute .. .
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[110] |
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109b
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Glumes nearly glabrous or pilose (with pubescence of short [<1 mm] hairs); lower glume apex blunt, obtuse, or rounded. ( Culms robust, trailing and rooting at lower nodes. [HAW - NAT] [FAC] [GUM - NAT] [FAC]
Dichanthium caricosum (L.) A. Camus
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110a
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(107) |
Culms slender, erect, tufted. Racemes nearly glabrous, sessile, attached at a common point on a peduncle. Glumes glabrous or nearly so. { Found in dry pasture land on most of the islands [HAW - NAT]Dichanthium tenue (R. Br.) A. Camus
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110b
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Racemes not attached at a common point on the axis. Racemes and glumes with at least some hairs .. .
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[111]
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~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~
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111a
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(107) |
Inflorescence of (1)2 to 15 racemes. Pedicles of pedicellate spikelets glabrous and lack a translucent medial line. Lower glumes of sessile spikelet narrowly oblong with bulbous-based hairs along margin. Angleton grass [HAW - NAT] [FACU]Dichanthium annulatum var. annulatum (R. Br.) A. Camus
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111b
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Pedicles of pedicellate spikelets with a translucent medial line (may be very difficult to see, but presence puts specimen in genus Bothriochloa) .. .
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[116]
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