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Genus Digitaria Family Poaceae

Description: Erect to prostrate perennials or annuals.

Leaves with ligule membranous; blade rolled in bud, often soft and hairy.

Inflorescence of slender spike-like racemes digitately or subdigitately arranged.

Spikelets in groups of 2 or 3, 1 subsessile and the other(s) shortly pedicellate, alternate in 2 rows on 1 side of the axis, closely appressed to it, dorsally compressed, falling entire; florets 2, the lower sterile, the upper bisexual. Glumes not alike, the lower minute, sometimes absent, the upper 3–5-nerved, rarely 1-nerved or nerveless. Lemmas 2, the lower usually as large as the upper lemma, 7- or 8-nerved, rarely 3-nerved, usually hairy, nerves parallel and prominent; upper lemma firm with hyaline margins, covering most of the back of the palea, faintly 3-nerved. Paleas 2, the lower minute, the upper equal to the upper lemma,


Distribution and occurrence: World: c. 250 species, tropical & warm-temp. regions. Australia: c. 44 species (c. 35 species native, c. 9 species naturalized), all States.

Text by S. W. L. Jacobs & C. A. Wall
Taxon concept:

Taxa not yet included in identification key
Digitaria eriantha

 Key to the species 
1Racemes very long, rigid, spreading and diverging at maturity, the basal 2–12 cm of each raceme without spikelets (rarely with a few spikelets at the base then bare for several cm), lower branches whorled2
Racemes long or short, usually not stiff, with spikelets at the base, rarely bare for a few mm (or up to 2 cm in D. brownii); lower branches ± whorled6
2Spikelets 2–3.5 mm long; spikelets with silky hairs up to 2.5 mm long that obscure the outline; leaves greyish-pubescent3
Spikelets 3.5–5 mm long, hairs present but not usually obscuring the spikelet outline; leaves ± greyish-pubescent
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4
3Spikelets c. 2.5 mm long; upper glume and sterile lemma villous (with long wavy hairs) on the back, both base and apex being obscured by hairsDigitaria ammophila
Spikelets c. 3–3.5 mm long with hairs on the sides and back of the upper glume and lower lemma but not obscuring the base and apex, stiff bristles also present
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Digitaria hystrichoides
4Spikelets 3.75–5 mm long, acute, upper glume slightly shorter and narrower than the spikelet and not conspicuously separated from the lower glume; short hairs 0.5 mm long in raceme axilsDigitaria divaricatissima
Spikelets c. 5 mm long, appearing obtuse because of the spreading hairs; upper glume subequal to the spikelet and arising a little above the lower glume; hairs in branch axils 1–3 mm long; foliage greyish-pubescent
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5
5Racemes not branchedDigitaria coenicola
Lower whorled racemes often unilaterally branched
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Digitaria porrecta
6Sterile lemma with two prominent tufts of silky hairs a little below the middle of each side of the mid-nerve; upper glume silky-hairyDigitaria hubbardii
Sterile lemma without conspicuous hair tufts; upper glume ± hairy
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7
7Spikelets almost concealed by long silky hairs on the upper glume and lower lemma8
Spikelets ± hairy but hairs not concealing the spikelets, hairs shorter than the spikelet and not usually silky
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9
8Lower glume minute and hyaline or absentDigitaria leucostachya
Lower glume firm, usually acute, up to 30% as long as the spikelet
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Digitaria brownii
9Spikelets mostly ternate (borne in groups of three) pedicels arise at one point but longest pedicel may be partly fused with the rhachis giving the appearance of alternately paired and single arrangement10
Most spikelets borne in pairs; spikelets may appear ternate if one pedicel is branched
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13
10Spikelets <2 mm long; fertile lemma pale to purplish-black at maturity; pedicels without a ring of hairs at the apex; racemes digitate or subdigitate; spikelet hairs usually verrucose (sprinkled with tiny grains)11
Spikelets 2 mm or longer, fertile lemma purplish-black at maturity; ring of hairs often present at the top of the pedicel; some hairs on upper glume and lower lemma with club-shaped or coiled tips, not verrucose; racemes variously arranged
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12
11Fertile floret purplish-black, racemes 2–13Digitaria violascens
Fertile floret pale or brown, not purplish-black, racemes 2–3 (rarely more)
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Digitaria longiflora
12Pedicels with a ring of short hairs at the apex (visible when the spikelets have fallen)Digitaria ternata
Ring of hairs not present at the top of the pedicel
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Digitaria ischaemum
13Upper glume equal to or subequal to the spikelet14
Upper glume up to 75% the length of the spikelet
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16
14Spikelets 2.5–3.5 mm long; lower glume absent; racemes digitate of subdigitate (the common axis up to 1 cm long)Digitaria aequiglumis
Spikelets 1.5–2.2 mm long; lower glume minute to 25% the length of the spikelets; racemes arising from a common axis 3–10 cm long
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15
15Spikelets glabrous on internerves and margins of upper glume and lower lemma with a few appressed hairs; tufted perennial with culms to c. 1.5 m tallDigitaria parviflora
Spikelets with hairs between the nerves of upper glume and lower lemma, at first appressed but later spreading and conspicuous, white or purple; delicate plants rooting at lower nodes, culms up to 40 cm tall
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Digitaria diffusa
16Upper glume <50% as long as the spikelet (usually up to 30% as long)17
Upper glume >50% the length of the spikelet (if<50% then the spikelet at least 2.5 mm long)
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18
17Lower glume absent, upper glume 10–25% as long as the spikeletDigitaria orbata
Lower glume present, often very small; upper glume 25–35% as long as the spikelet
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Digitaria breviglumis
18Spikelets not more than 2.75 mm long; perennials19
Spikelets 2.75–3.5 mm long; hairy annuals
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22
19Racemes digitate, 2–3; slender stoloniferous perennial often forming a dense turfDigitaria didactyla
Racemes 3–15 on a primary axis 3–10 cm long
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20
20Upper glume acute; sterile lemma as long as spikeletDigitaria velutina
Upper glume obtuse; sterile lemma usually slightly shorter than spikelet
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21
21Margins and internerves of upper glume and lower lemma glabrous or with very short hairs; short hairs in axils of racemesDigitaria ramularis
Margins and internerves of upper glume and lower lemma hairy; long hairs in axils of branches
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Digitaria sp. aff.ramularis
22Upper glume 30–50% as long as the spikelet; nerves of the lower lemma scaberulous (sometimes with bristles) and evenly spacedDigitaria sanguinalis
Upper glume 50–75% as long as the spikelet; nerves of the lower lemma smooth, usually with a wide interspace on each side of the mid-nerve; spikelets often with a ciliate frill (hard to distinguish from D. sanguinalis)
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Digitaria ciliaris

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