Dichanthium tenue (R.Br.) A.Camus

hairless bluestem


Info

Subfamily: Panicoideae
Genus etymology: Dichanthium = "paired flower" [Greek] refering to the difference between the basal homogamous and the other heterogamous spikelets
Species etymology: tenue = "thin" [Latin] refering to the pedicels
Photosynthetic type: C4 (warm season)
Nativity: naturalized - accidental
First recorded in Hawaiʻi: 1936

Map

 Distribution of Dichanthium tenue in Hawaiʻi.

Inflorescence

Dichanthium tenue Inflorescence
Dichanthium tenue Inflorescence
Dichanthium tenue Inflorescence
Dichanthium tenue Inflorescence
Dichanthium tenue Inflorescence

Plant

Dichanthium tenue Plant

Habit

Dichanthium tenue Habit

Spikelets

Dichanthium tenue Spikelets

Node

Dichanthium tenue Node

Description

Habit: Perennial; caespitose. Culms erect; 30-70 cm long; 2-4 -noded. Culm-internodes channelled. Culm-nodes bearded. Lateral branches lacking. Leaf-sheaths glabrous on surface. Ligule a ciliolate membrane; 0.5-0.75 mm long; truncate. Leaf-blades 7-15 cm long; 2-3.5 mm wide. Leaf-blade surface scaberulous, or scabrous; glabrous, or pilose; with tubercle-based hairs. Leaf-blade apex acuminate. Inflorescences: Inflorescence composed of racemes. Racemes 1-3; single, or paired, or digitate; 3-6 cm long. Rhachis fragile at the nodes; subterete; ciliate on margins. Rhachis hairs lengthening towards internode tip; 1-1.5 mm long. Rhachis internodes linear. Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels linear; without a translucent median line; ciliate; hairy all along but hairs longer above; with 1-1.5 mm long hairs. Spikelets: Basal sterile spikelets well-developed; 2-4 in number; barren; smaller than fertile. Basal sterile spikelet lemmas awnless. Companion sterile spikelets well-developed; male; elliptic; 4-6 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes 9 -veined; ciliate on margins. Companion sterile spikelet lemmas enclosed by glumes; muticous. Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets oblong; dorsally compressed; 4-6 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus pilose; base obtuse; attached transversely. Spikelet callus hairs 0.5-0.9 mm long. Sterile Florets: Basal sterile spikelets well-developed; 2-4 in number; barren; smaller than fertile. Basal sterile spikelet lemmas awnless. Companion sterile spikelets well-developed; male; elliptic; 4-6 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes 9 -veined; ciliate on margins. Companion sterile spikelet lemmas enclosed by glumes; muticous. Fertile Spikelets: Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets oblong; dorsally compressed; 4-6 mm long; falling entire; deciduous with accessory branch structures. Spikelet callus pilose; base obtuse; attached transversely. Spikelet callus hairs 0.5-0.9 mm long. Glumes: Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume oblong; 1 length of spikelet; chartaceous; of similar consistency above; without keels; keel-less except near apex; 8-9 -veined. Lower glume surface smooth, or asperulous. Lower glume margins ciliolate. Lower glume apex truncate, or obtuse. Upper glume lanceolate; 1-keeled; 3 -veined. Florets: Basal sterile florets barren; without significant palea. Lemma of lower sterile floret ovate; hyaline. Fertile lemma linear; hyaline; without keel; 1 -veined. Lemma apex entire; awned; 1 -awned. Principal lemma awn apical; geniculate; 22-28 mm long overall; with twisted column. Column of lemma awn glabrous. Palea absent or minute. Flowers: Anthers 3; 1 mm long. Fruits: Caryopsis with adherent pericarp; oblong; 2.5 mm long. Distribution: Australasia: Australia. Pacific: southwestern and north-central.
(Description source: Clayton, W.D., Vorontsova, M.S., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. Available at https://powo.science.kew.org )