Diplachne fusca (L.) P.Beauv. ex Roem. & Schult.

Global description

Diplachne fusca is a vivacious grass from aquatic and flooded environments, which is common in rice fields. It is a tufted plant which has rhizomes of variable development, and erect stems which reach 1.50 m in height. The thin, tapered leaves are flat to rolled. They have a developed, triangular and pointed membranous ligule. The inflorescence is large, elliptical in shape. It reaches 30 cm long. It is made up of 10 to 30 erect racemes which carry the multi-flowered spikelets, spaced between them. The lower lemma has a short awn. The ellipsoid-oblong, dorsally compressed grain is less than 2 mm long.

General habit

Vivacious grass erect and growing in a tuft, which reaches 1.50 m in height.

Underground system

The underground system is rhizomatous, with rhizomes of very variable length and fasciculated roots.

Culm

The culm is hairless, cylindrical. It measures 60 cm to 1.50 m in height. It is erected or bent towards the base then straightened. It is branched and takes root at the lower nodes. The nodes are hairless.

Leaf

The blade is rigid, curled, narrowly linear, ending in a threadlike point. It measures 25 to 55 cm long and a maximum of 5 mm wide. It is glaucous and glabrous, but scabrous on the faces, as well as on the margin. The hyaline membranous ligule is pointed, often laciniate. It measures 3 to 9 mm long. The sheath is streamlined, streaked, glabrous.

Inflorescence

The inflorescence is an erect or slightly curved elliptical panicle that is 20 to 35 cm long. It is large, made up of 10 to 30 erect racemes, solitary or grouped by 2 to 3, with slightly flexible scabrous axes, 7 to 15 cm long.

Spikelet

The spikelets are carried by a 1 mm long pedicel. They are composed of 6 to 11 flowers. They are elliptical to narrowly elliptical, compressed laterally. They are 8 to 15 mm long. They are gray green in color. The glumes are unequal, scabrous on the mibrid. The lower glume is lanceolate, pointed at the end, with a single keel and a single vein. It measures 2.1 to 4.6 mm long. The upper glume is oblong, with an acute or obtuse end, mucronate, with 1 keel and 1 to 3 veins. It measures 3.3 to 7.4 mm long. The fertile lemmas are 3.2 to 5.9 mm long. They are narrowly oblong, with bidentate or pluridentate apex, weakly keeled, silky, weakly ciliated on the lateral veins. They have a short awn which reaches 1.6 mm long. The fertile paleas are 2-nerved and 2-keeled. The keels are scabrous. The palea has a pubescent surface and has an awn 0.8 mm long. The upper florets are sterile, similar to the fertile lower florets but less developed. The olive-green spikelets become pale when ripe.

Grain

The grain is elliptical-oblong, flattened dorsally. It measures 1.6 to 1.8 mm long.

Worldwide distribution

Diplachne fusca is present in North Africa and in all tropical Africa, in the Indian Ocean but not in Reunion island and Mauritius, in temperate and tropical Asia, in all Oceania and the Pacific islands, in the USA in Central America and tropical and temperate South America, in the Caribbean.

https://www.gbif.org/species/8010581