20 MEMQIRS OF THE NEW YORK BOTANICAL GARDEN [VOL. 10 



Distribution. Only the type collection known ; quite distinctive in habit, size 

 of spikes and form of spicular bracts. 



16. Xyris decussata Gleason, Bull. Torrey Club 56: 392. 1929. 



Type. Summit Mt. Roraima, Bolivar, Venezuela, Tate 427 (NY). 



Distribution. Known only from Mt. Roraima, Ilu-tepui, Ptari-tepui, and the 

 Chimanta Massif, all of the Gran Sabana, Bolivar, Venezuela. 



Additional specimens. Roraima: Steyermark 58806; Chimanta: Steyermark 

 75757, Steyermark & Wurdack 347, 487, Wurdack 34307; Ptari-tepui: Steyer- 

 mark 59683; Ilu-tepui : Maguire 33408. 



17. Xyris witsenioides Oliver in im Thurn, Timehri 5: 207. 1886; Trans. 



Linn. Soc. II. 2: 285. pi. 50, f. 9-15. 1887. 



Type. Mt. Roraima [Venezuela], im Thurn 240 (K). 



Distribution. Caulescent loose-tussock plants at high altitudes, the densely 

 imbricate leaves forming broad frond-like plates. . Venezuelan Guayana ; fre- 

 quent on the tepuis of the Gran Sabana and Cerro Neblina, Amazonas. 



18. Xyris riparia Maguire & Smith, sp. nov. Fig. 5, A-E. 



Herbae longe caulescens sed verisimiliter non ramosae ; foliis densissime 

 distichis et laminam frondosam formantibus, ad 24 cm longis; vaginis ca. 

 10 cm longis, ad basin versus gradatim dilatatis, apice eligulatis et cum laminis 

 confluentibus, omnino atro-castaneis, laevibus, extus convexis ecarinatisque, intus 

 dense ciliatis, alibi glabris ; laminis linearibus, acuminatis, spiraliter tortis, 2 mm 

 latis, sublaevibus, margine haud incrassatis, margine obscure scabridulis, alibi 

 glabris ; scapo ultra 30 cm alto, subtereti, ecostato, ex sicco leviter sulcato, glabro ; 

 vagina scapi quam foliis bene breviore, breviter laminata; spica subglobosa, 10 

 mm longa, multiflora ; bracteis decussatis, atris, area dorsali carentibus, vetustis 

 aliquid laceratis sed vix normaliter, basilaribus valde reductis, alteris ovatis, 

 obtusis, sepala aequantibus vel superantibus ; sepalis lateralibus liberis, equi- 

 lateralibus, anguste lanceolatis, acuminatis, 7 mm longis, late carinatis et ad 

 apicem versus serrulatis ; placentis basilaribus. 



Type. Flowers yellow, frequent in clumps at stream edge, scrub forest near 

 Summit Camp, alt. 1925 m, Chimanta Massif, central section, 2 Feb 1955, Boli- 

 var, ^nezuela, J. A. Steyermark & J. J. Wurdack 361 (holotype NY, isotype 

 US). 



19. Xyris ptariana Steyermark, Fieldiana Bot. 28(1) : 110. /. 16, I, J. 1951. 



Type. Forming dense tufts, wet bluffs, alt. 2000 m, Ptari-tepui, Gran Sabana, 

 Bolivar, Venezuela, Steyermark 59919 (isotype NY). 



Distribution. High altitudes on Ptari-tepui and the Chimanta Massif, Gran 

 Sabana, Bolivar, and Cerro Sipapo, Amazonas, Venezuela. 



20. Xyris xiphophylla Maguire & Smith, sp. nov. Fig. 6, A-E. 



Herbae longe caulescens sed verisimiliter non ramosae; foliis densissime 

 distichis et laminam frondosam formantibus, 24-30 cm longis, glabris; vaginis 

 magnis, 12-15 cm longis, acute carinatis, apice 8-9 mm latis et ligula parva 

 acuta praeditis, basi paulo ampliatis et atro-castaneis, alibi viridibus; laminis 



