Global description
Echinochloa pyramidalis is a big robust and rhizomatous herbaceous plant that reaches 5 m high. The stem of the grass, which reaches 1.5 cm in diameter, is radicand at its base and often prostrate for a long distance before it becomes erect. The leaves have a smooth sheath, a ciliated ligule, a flat and hairless leaf blade, linear, with scabrous margins. The inflorescence is large (up to 40 cm high), erect to slightly tilted, oval to lanceolate. It consists of many branches which carry bundles of spikelets arranged in tight rows. The spikelets are ovoid, sharp and of big size. Each of them contains 2 flowers: the internal, which is empty or male, the external which is fertile.
General habit
Large perennial herbaceous plant, with large rhizomes that measure 1 to 5 m high.
Underground system
The underground system is a big rhizome from which well-developed roots that form a carpet emerge.
Culm
The culm of the grass is very robust, cylindrical, can reach up to 1.5 cm in diameter at the base and glabrous. It is more or less spongy in its lower portion which is often extensively prostrate on the ground or water and radicand at the nodes. Then it becomes erect and branched. The nodes are pubescent except the superiors who are almost glabrous.
Leaf
The sheath is glabrous, except that of the lower leaves which sometimes have hairs with tuberculate base. The ligule is represented by a line of well-developed cilia (sometimes absent in the upper leaves). The leaf blade is flat, linear elongated, 8 to 60 cm long and 2 to 2.5 cm wide, with rounded base and pointed tapered end. It is stiff, glaucous, usually glabrous (sometimes provided with tuberculate hairs), with cartilaginous scabrous margin.
Inflorescence
The inflorescence is a large erect or slightly tilted panicle, oval to narrowly lanceolate in shape. It measures 8 to 40 cm high. It is composed of 20 branches or more, erect, flexuous, which can be simple or branched, solitary or grouped. These shoots are 3 to 20 cm long. The main axis is angular, scabrous on the edges, hairy on nodes. The secondary axes are angular, scabrous and ciliated at the edges.
Spikelet
The spikelets are grouped in bundles. They are ovoid to ellipsoidal, pointed at the end, glabrous or hairy, 2.5 to 4 mm long. They are green or purplish in color. The glumes are unequal in size, scabrous on ribs. The lower hull is oval, with acute apex, often covered with fine hairs. It measures half the size of the spikelet and is traversed by 5 scabrous ribs. The upper hull is oval, pointed at the end. It is as long as the spikelet and marked with 5 to 7 scabrous ribs. The spikelet is composed of 2 flowers: an internal male or empty flower, external fertile flower, with three stamens. The inferior lemma of the flower is similar to upper glume. Lower lemma of fertile flower is a little tough, with convex back, smooth and shiny, and yellow in color.
Grain
The grain is elliptical, large, 2 to 2.5 mm long, plan convex, mucronate.
