Rhynchospora holoschoenoides (Rich.) Herter

Code

RHCHO

Growth form

sedge

Biological cycle

vivacious
 
Habitat

marshland

 

Global description
 
Rhynchospora holoschoenoides is a vivacious, glabrous, herbaceous sedge, with short rhizome. The floral axis is generally solitary with a triangular section. The sheaths are brownish or pale. The leaves are simple, entier, alternate, arranged on the 3 sides of the stem. They are mostly present at the base of the plant. The lamina is rigid, linear, often shorter than the grass stem. The inflorescence is subtended by leafy bracts and consists of 1 to 3 distant corymb, in the form of an umbel. Each corymb is formed of 3 to 7 unequal rays, bearing 5 to 12 glomeruli.
 
General habit
 
Rhynchospora holoschoenoides is an upright vivacious herb with solitary stems or few, forming small tufts that can reach 80 cm in height.
 
Underground system
 
The underground apparatus consists of a short rhizome and fibrous adventitious roots.
 
Culm
 
The culm is glabrous and smooth, solid, of triangular section at 3 acute angles, rarely cylindrical or compressed. It measures 30 to 80 cm in height and 1 to 3 mm in diameter. It often appears gnarled in the upper part.
 
Leaf

The leaves are simple alternate, in tristichous arrangement on the 3 sides of the grass stem. They are few in number, mainly basal, with brownish or pale sheaths. Basal leaves are often limited to a sheath without lamina. The caulinary leaves have a rigid lamina, linear, 3 to 5 mm wide, generally shorter than the grass stem. The apex is acute. Both faces are glabrous, the margin is very slightly scabrous. At the junction of the sheath and the lamina, a membranous or ciliated ligule may be present or absent.
 
Inflorescence
 
The inflorescence is usually terminal, rarely lateral. It consists of 5 to 12 brown glomeruli, at the end of 3 to 7 floral stalk of different length, forming a sub-umbeliform corymb. The inflorescence is subtended by foliaceous bracts similar to the leaves, while the bracts at the base of the glomeruli are bristles. The glomeruli are 8 to 12 mm in diameter and are brown in color.
 
Spikelet
 
The spikelets constituting the glomeruli are lanceolate to oval lanceolate, 4 to 6 mm long. They contain 7 to 8 glumes and 2 to 4 flowers of which only one is fertile. The basal glumes are narrowly oval, much shorter than the lanceolate, membranous, brown-green, brown-greenish, and mucronate glumes. 6 rigid, brown bristles of unequal sizes are present at the base of the ovary. The style is red, 3 to 4 mm long and simple. Staminods are shorter than stamens.
 
Fruit
 
The fruit is a brownish achene, 1 mm long and 0.75 mm wide, sessile, obovate and biconvex, with weak undulating transverse lines.

 

Antilles: Rhynchospora holoschoenoides flowers and fruits all the year round.
French Guiana: Rhynchospora holoschoenoides flowers and fruits all the year round.

 

Rhynchospora holoschoenoides is a vivavious sedge that multiplies vegetatively by its rhizome and also produces seeds.

Antilles: Rhynchospora holoschoenoides is present from 0 to 300 m altitude, along forest roads, at the edge of ponds, ponds and streams.
Comoros: Absent.
French Guiana: R. holoschoenoides develops in the humid regions, at the edge of canals on the rice polder. It is also observed in the spontaneous vegetation of orchards with permanent cover, especially in areas that are temporarily wet. It is also a weed in wet or temporarily flooded and degradated pastures where it is often associated with Spermacoce capitata, Scleria gaertneri and Fimbristylis dichotoma. It is present in all pastoral areas of French Guiana.
Madagascar: R. holoschoenoides grows in hydromorphic soils that are mineral or rich in organic matter, fairly fertile but acidic. It is a weed of low-flooded lowland rice fields or present in the plain on the east coast, in marshes and bogs, in canals and along roadsides in wetland areas. It grows in sunny or slightly shaded places. It is found in intensive or semi-intensive rice cropping systems on the East Coast of Madagascar, up to about 500 m altitude.
Maurice: Absent.
Nicaragua: A common species in the very wet savannahs of the Atlantic and Pacific zones, from 0 to 200 m altitude.
Reunion: Absent.

 

Worldwide distribution

Rhynchospora holoschoenoides occurs in Central America, from Mexico to Brazil, the Caribbean, the West Indies, tropical Africa and Madagascar.
 

Local harmfulness

French Guiana: Rhynchospora holoschoenoides is an infrequent and scanty weed in orchards with permanent vegetaation cover. It is also found on the edge of rice fields. It is a very common weed in pastures, especially in lowland or temporarily flooded situations. It is present in 35% of grazing plots, but generally has a low cover (on average 7%). Locally this cover can be very high, up to 50% in very degraded pasture situations.
Madagascar: Rhynchospora holoschoenoides is a relatively not requent, rather localized and generally scarce species in rice fields. Its management does not present any particular difficulty. It can be locally abundant in the rice fields with peat soils of the East Coast.

 

Local control

Madagascar: On the East Coast of Madagascar, the rice fields are weeded with various hand tools before transplanting. The rice is hand weeded once during the crop cycle.

Herbarium pictures ReCOLNAT: https://explore.recolnat.org/search/botanique/simplequery=Rhynchospora%2520holoschoenoides