Rhynchospora corymbosa (L.) Britton

Global description

Rhynchospora corymbosa is a tall, upright vivacious species that grows up to 2 m tall. Its root system is fasciculated, resulting from a large short rhizome. The robust stems are triangular in section. The long, slender leaves are mostly basal. They are scabrid on the margin and the dorsal rib. The large, loose inflorescence is distributed in the upper part of the stem. It consists of a succession of brown spikelet corymbs grouped in bundles, and subtended by a large leaf bract. The fruit is a achene of yellow-brown color. It is surmounted by a conical element wider and as long as it is.

General habit

Robust vivacious plant in tuft.

Underground system

The root system is fascicular derived from a large short rhizome.

Stem

The stem measures 60 cm to 2 m in height and 3 to 10 mm in diameter. It is robust, triangular section, a little scabrous on the angles in its upper part.

Leaf

Many leaves are mostly inserted in the basal part of the stem. They are linear, tapered at the end. They are 20 to 90 cm long and 8 to 20 mm wide. They are thick, glabrous, strongly keeled, with scabrous margin, and the dorsal rib. Presence of a large membranous false ligule, opposite to the base of the limb. The sheaths are long, of light brown color for the basals.

Inflorescence

Inflorescence large and wide, 10 to 40 cm long. It corresponds to a staging of corymbiform inflorescences, 2-4 in axillary positions and one in the terminal position, all located in the axils of large leaf bracts.

Spikelet

The spikelets are solitary or grouped in bundles by 2 to 10. They are carried by axes of very different lengths. They are ovoid-lanceolate, 6-9 mm long, brown in color. They contain only one achene. The glumes are oval to oval-oblong, broad, almost distichous, with an obtuse mucronate tip. They are 2.5 to 6 mm long. They are membranous, of a light brown color, with a single vein. Each spikelet consists of 2 to 3 flowers, the lower is complete, the upper containing only stamens. The lower flower is surrounded by 6 rigid bristles that persist at the base of the achene. The stamens are 3 in number. The style is elongated, with a broad conical base, undivided and extending largely at the end of the spikelet.

Fruit

The fruit is an obovoid or ovoid-oblong achene, 2.5 to 3.5 mm long and 2 mm in diameter, with a finely pitted tegument, a dull yellow-brown. It is surmounted by a conical piece corresponding to the increase of the base of the style, the same length as it but wider, furrowed on both sides and more or less scabrous. At the base are six stiff, scabrous bristles, longer than the achene.

Worldwide distribution

Rhynchospora corymbosa is present in all tropical and subtropical regions. Present everywhere in Indonesia.

https://www.gbif.org/species/2721495