Fig. 1, A-F.
Type. Leaves stiff, reddish-brown toward base, brittle, flowers yellow, infrequent in wet places, scrub and low forest (8-10 m ) , on shoulder of east flank, above Thompson Camp, alt. 1418-1525 m, 10 Aug 1960, Upper Mazaruni River Basin, Mt. Ayanganna, British Guiana, 8. 8. & C. L. Tillett & R. Boyan 45074 (holotype NY, isotype US). Paratypes. British Guiana, Merume Mts., Partang River: along ridge trail, alt. 1140 m, infrequent in marshy areas in forest, 3 Jul 1960, Tillett d- Boyan 43974; frequent on sand and rocks of stream bed, Tillett & Boyan 43998.
This species is closely related to Xyris fallax Malme, as evidenced by its multicostate scapes and by the practically identical form of the seeds. However, it is strikingly differentiated by the presence of rhizomes and coarsely and laxly nerved rugulose leaves that are often suffused with a brilliant red hue.