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CPIE Notebook Project - Grasses of Hawai‘i Page 16

Open Paniculate Inflorescences, long awns

102a (83) Inflorescence an erect or drooping panicle of large spikelets: spikelets over 5 mm long [103]

Inflorescence erect, panicle of spikelets over 3 mm long, but not over 5 mm


Panicles dense, spikelets narrow, up to 2.5 mm long. Medium-size perennial grass with hairy, sticky leaves (particularly the sheaths). Strong-smelling (like molasses). Inflorescence varies from very narrow to narrow ovoid, purple-tinged. { Widely distributed in dry to mesic sites above 400 ft elevation. Molasses grass. [NAT]

Melinus minutiflora P. Beauv.
103a (102) Spikelets 6 mm long excluding awn, paired: sessile spikelet perfect, not awned; pedicellate spikelet awned (basal spikelets on a raceme not always awned).


Spikelets 9 mm (>5/16 in) or more long not including awn(s), which exceed length of spikelet

104a (103) Inflorescence of one to many racemes, these typically paired or digitally arranged on erect branchlets; spikelets paired, more or less similar, but only sessile one with long awn. Medium size grasses. Dichanthium spp.

104b Sorghum spikelets Paired spikelets disimilar, stalked spikelet (two at branch end) narrow, sterile or male only; sessile spikelet with a twisted and bent awn. Leaves wide, with conspicuous midrib. blade and sheath glabrous, except densely pubescent at throat; ligule membranous, dark, conspicuously longest at middle, fringed with short tight hairs.{ Inflorescence varies from crowded to somewhat open, narrow ovoid to spindle-shaped, or drooping. Large grasses. Sorghum spp.

Figure 16A. Photo drawing of (seven) Sorghum spikelets. Note terminal sessile spikelet is associated with two pedicellate spikelets, the others with one each.

105a (104) Raceme somewhat fragile. Grain conspicuous, shiny white at maturity. { Large rhizomatous, perennial. Johnson grass. (Fig. 16A) [NAT]
Sorghum halepense (L.) Pers.

105b Raceme tough, tardily disarticulating. Grain large, spreading the glumes (some black), colored reddish brown at maturity. { Large annual. [NAT]
Sorghum bicolor (L.) Moench
107a (103) Large perennial with dense, open, but typically drooping inflorescence. Apparent spikelets on mostly stiff branches arising from the leaf sheaths. Actual spikelets are mostly much reduced and number 3-6 above a 3-3.5 cm (>1 in) spathe. Two spikelets with long awns in each complex raceme. { Naturalized in dry to mesic pastures and other disturbed sites to 2500-ft elevation. Lyon's grass. [NAT]
Themeda villosa (Poir.) A. Camus

Spikelets single on narrow pedicels branching off the rachis. Medium to large grass with open and not particularly dense inflorescence. Two awns per spikelet. Avena spp.

108a (107) Rachilla and lemma glabrous or sparesely pubescent. Long awns straight or weakly bent. Florets not deciduous [109]

Rachilla and lemma hairy. Long awns typically bent. Florets readily deciduous, disarticulating above glumes and between floret pair

109a (108) Lemma glabrous at base. Long awns typically straight. Tip of lemma entire or slightly bilobed, without awns. Florets not deciduous, persisting. { Medium to large annual grass, cultivated as forage, but naturalized in disturbed places and pastures. Common oat. [ORN,NAT]
Avena sativa L.

Lemma glabrous but rachilla of second floret ciliolate on upper edges. Long awns slightly bent. Tip of lemma with two short awns. { Medium to large annual grass, cultivated as forage on Kaua‘i (coll. 2013). Hybrid oat. [ORN]

Avena sativa hybrid or cross?
110a (108) Tip of lemma with two short awns. Lemma hairs white. Naturalized on O‘ahu and Hawai‘i. [NAT]
Avena barbata Pott ex Link

Tip of lemma toothed, but without bristles or awns. Lemma hairs yellow to brown. Wild oat [NAT]

Avena fatua L.

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