Vossia cuspidata (Roxb.) Griff.

Global description

Vossia cuspidata is a vivacious, robust, almost glabrous, aquatic grass with floating or submerged stems, strongly rooted at nodes and up to 7 m long and with upright stems up to 1 m tall. The stem is thick and spongy in its aquatic part. The leaves are linear, with tapered and pointed ends, flat and straight, scabrous and sharp on the margin. The sheath is glabrous. The ligule is short membranous surmounted by a line of hair. The terminal inflorescence is digitate, composed of 1 to 12 pale green subcylindrical racemes that reach 30 cm in length. The spikelets are grouped by 2, a sessile and a pedicellate, of similar shape, all 2 prolonged by a long flattened finely toothed awn.

General habit

Vivacious and robust, almost hairless, long-stemmed (up to 7 m) submerged or floating aquatic grass rooting extensively at nodes and producing upright stems that can exceed 1m in height.

Underground system

A highly developed fasciculated root system at submerged nodes. Brown roots forming big bun.

Culm

The culm is  turdy and spongy. It measures up to 2.5 cm in diameter. It is glabrous, of cylindrical section. The nodes are widely spaced.

Leaf

The leaves are simple alternate. The sheath is glabrous. The ligule is membranous, very short (1.5 to 2 mm high), surmounted by a fringe of short hairs. The long linear lamina, with a broad prominent white midrib, is flat and rigid, with a rounded narrowed base, a pointed tip, and a scabrous margin. It is 30 to 100 cm long and 5 to 25 mm wide. It is glabrous on both sides, except above the ligule where it is densely ciliated.

Inflorescence

The terminal inflorescence consists of 1 to 12 digitate racemes, sub-cylindrical spiciform, 10 to 30 cm long, pale green in color. Rachis and pedicels are scabrous, compressed down, widened at the top. The spikelets are grouped by 2, one is sessile, the other is pedicelled. The rachis disarticulates between pairs of spikelets.

Spikelet

The spikelets are extended by long flattened awns finely toothed. They are similar in shape and contain 2 flowers. The pedicellate spikelet is a little smaller than the sessile one. They are ovoid narrow, lanceolate, 20 to 40 mm long with the awn (1.5 to 3 cm long and 2 mm wide). The lower glume is leathery, scabrous and keeled. It is prolonged by the long awn. The upper glume is navicular, asymmetric and bicarenated. The lower flower is male with lemma and palea subequal, hyaline. The upper flower is fertile with lemma and palea subequal, hyaline. Lemma finely ciliated on the margins and at the top and palea with scabrous keels and finely ciliated on the margins and at the top. They are 7 to 8 mm long. The anthers are yellow in color and 4 mm in length.
This species rarely flowers.

Worldwide distribution

Vossia cuspidata occurs in tropical Africa and in South-East Asia.

https://www.gbif.org/species/5289907