Panicum pansum Rendle

Global description

Panicum pansum is a loose tufted, upright grass plant. The leaves are long and slender, pubescent to hispid. The ligule is ciliated. The inflorescence is a very loose panicle, ellipsoidal, with numerous long branches. Spikelets are grouped in pairs. They are ellipsoidal with 2 flowers, one sterile at the base and they measure 2.5 to 3 mm. The lower glume measures more than half of the upper glume, it has 3 to 5 veins. The lower lemma has an acute apex, it presents 7 to 9 veins. The upper lemma is shorter, smooth and closes on the palea. The grain remains included in the palea and the lemma.

First leaves

The first leaves have a rolled prefoliation. The blade is linear and very slender to the top, 6-10 cm long and 4-5 mm wide. It is erect obliquely, pubescent to hispid and has a ciliated margin. The main vein is carved into a gutter. The ligule is ciliate and short. The sheath is cylindrical and pubescent to hispide throughout its length. The hull is not very marked.

General habit

The port of Panicum pansum is loose tuft and erect. This species is up to 1 m tall.

Underground system

The roots are fasciculate and can develop at the lower nodes when in contact with the soil.

Culm

The culm is cylindrical, 2 to 3 mm wide. It is smooth and glabrous, sometimes tinged with purple. The knots are glabrous and light in color.

Leaf

The leaves are simple and alternate. The sheath is cylindrical and weakly keeled. It is glabrous in the lower part then becomes pubescent to hispid in the upper part. The hairs are transparent and tubercular at the base. The ligule is ciliated and 1 mm high. The lamina is linear, long tapered to the apex peak sharp. It is 10 to 30 cm long and 5 to 7 mm wide. It is abundantly pubescent to hispid. The margin is ciliated with transparent, tubercular hairs. The blade is marked in the middle by a central rib in gutter, light color.

Inflorescence

The inflorescence is a very loose ellipsoidal panicle, 20 to 40 cm long and 15 to 30 cm wide. It is formed of many long branches, thin and flexuous. The axil of branches is sometimes marked by long hairs. The branches can measure 10 to 15 cm and are finely scabrous.

Spikelet

The spikelets are grouped in pairs at the end of the branches. They are borne by filiform pedicels, 1 to 3 mm long. One spikelet is always longer pedicelled than the other. The spikelets are ellipsoidal and symmetrical. They are 2.5 to 3 mm long and 1 mm wide. They are often tinged with purple. They include 2 flowers. The lower flower is male or sterile while the upper flower is fertile. The lower glume is oval, acute apex. It measures more than two-thirds of the length of the upper glume and has 3 to 5 longitudinal veins. The dorsal vein is finely scabrous. The upper glume is as long as the spikelet, it is glabrous, with a rounded or acute apex often turned inwards. The lemma of the lower flower is oval, acute apex. It has 7 to 9 longitudinal ribs. The lower palea is short. The lemma of the upper flower is smooth. It is shorter than the lower lemma and completely hidden by it. Its edges close almost completely on the palea.

Grain

The grain remains inserted in the palea and the lemma. It is fusiform, 2 mm long and 0.7 mm wide.

 

https://www.gbif.org/fr/species/4130951