Global description
Panicum repens is a vivacious grass, with long rhizome, and rooting at nodes. The flowering stems are erect, slender to more or less robust, glabrous, with many nodes of 30 to 100 cm high. The leaves have a linear blade which is glabrous or more or less pubescent, 6 to 25 cm long and 2 to 8 mm wide, with cartilaginous margin and membrane-ciliated ligule. The inflorescence is a narrowly oblong panicle, 5 to 20 cm long, with obliquely erect branches, carrying small groups of 2 to 6 spikelets. The spikelets are oval, glabrous, 2 to 3 mm long and often tinged with purple.
First leaves
The first leaves are simple, alternate, vertically erect, rigid, with a coiled aestivation, very acute at the apex. The ligule is membrane-ciliated, and short.
General habit
It is a rhizomatous grass, stoloniferous, extensively branched, turfting, and forming large patches.
Underground system
Underground system consists of very knotty rhizomes, abundantly branched, measuring up to 7 m long. The apex is very pointed. The rhizomes can thicken to the point of resembling ginger rhizomes. Many fibrous roots at the nodes.
Culm
The culm is cylindrical, slender to more or less robust, glabrous, slightly branched or undivided, 2 to 3 mm in diameter, 30 to 100 cm high, holding the inflorescence. The numerous nodes are glabrous.
Leaf
Leaves are simple, alternate in distichous arrangement. The sheath is usually glabrous, with ciliated margin. The ligule is membrane-ciliated, 5 mm high. The lamina is linear lanceolate, 6 to 25 cm long and 2 to 8 mm wide, flat or more often rolled, rigid, remaining completely erect. The apex is very acute in a short pointed tip. The underside is smooth and glabrous, while the upper surface is scabrous with some long hairs with tuberculous base. The margin is cartilaginous, scabrous.
Inflorescence
The inflorescence is a closely oblong panicle, 5 to 20 cm long, contracted,most of the time erect. The ascending branches are scabrous with small racemes reduced to 2 to 6 spikelets, at their ends.
Spikelet
The spikelets are oval with acute apex, 2 to 3 mm long, glabrous, often tinged with purple. They are held by a corrugated pedicel. The glumes are very different and very unequal. The lower glume is small, broadly oval, with obtuse or shortly acute apex, equal to 1/3 of the length of the spikelet, with one distinct midrib. The upper glume is of the size of the spikelet, oval, with an acute apex and has 7 to 9 projecting ribs. The lower flower is male. It comprises of a lemma quite similar to the upper glume, with 9 veins, an ample margin and a palea of the same size, and with 2 keels. The external flower is fertile, elliptical oblong with acute apex, 2 mm long. It includes a lemma and a white palea, cartilaginous, leathery, smooth.
Grain
Largely oblong grain, 1.2 to 1.5 mm long, white.