16 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN [VOL. 10 



71. Leaves smooth, 0.5-1 mm broad; staminodes penicil- 



late. 71. X. paraensis. 



71. Leaves either transverse-rugulose on the sides or 

 tuberculate-scabrid on the edges, 2-3 mm broad; 

 staminodes glabrous. 72. X. savanensis. 



4. Xyris involucrata Nees ab Esenbeck in Jour. Bot. Hooker 2: 397. 1840. 

 Type. Schomburgk 1054, " British Guiana in 1836-40." 



Distribution. Extraordinarily distinctive and attractive because of the con- 

 spicuous radiate involucral bracts; a short-lived perennial confined to moist 

 sandy savannas throughout Guayana, from alt. 100-1200 m, and on the Rio 

 Negro in Brazil. 



5. Xyris spruceana Malme, Bihang Sv. Vet.-akad. Handl. 26 (3) 19 : 12. pi. 1, 



f. 2. 1901. 



Type. Ad fluv. Guainia v Rio Negro supra ostium fluvensis Casiquiari, in 

 1854, Spruce 2993 (isotype NY). 



Distribution. Occasional in moist sandy places, chiefly savannas, at alt. 100- 

 300 m ; drainage of the upper Rio Negro and its tributaries in Amazonian Vene- 

 zuela and Colombia, viz., the Casiquiari, Guainia, Apaporis, Igana, and Vaupes. 



6. Xyris cryptantha Maguire & Smith, sp. nov. Fig. 2, A-E. 



Herbae acaules dense caespitosae, rhizomatibus nullis; foliis 7-9 cm longis, 

 rigidis, laevibus; vaginis ca. 15 mm longis, rubro-brunneis, basi abrupte dila- 

 tatis, apice eligulatis et cum laminis confluentibus, intus dense longeque ciliatis, 

 alibi glabris; laminis teretibus, subulato-acuminatis, 0.3 mm diam., glabris, 

 pallido-punctulatis ; scapo erecto, ad 12 cm alto, tereti, 0.3 mm diam., glabro, 

 laevi ; vagina scapi eas foliorum subaequans, breviter laminata ; spica anguste 

 obconica, 1-2-flora; bracteis duabus basilaribus anguste oblongis, obtusis, 8 mm 

 longis, haud carinatis, marginibus albidis, membranaceis, mox laceratis, area 

 dorsali magna, angustissima, acuminata, bracteis reliquis similibus sed gradatim 

 minoribus ; sepalis lateralibus liberis, linearibus, acutis, 5.5 mm longis, carinatis, 

 glabris, laevibus; placentis basilaribus. 



Type. Flowers yellow, locally frequent, Sabana Pacimoni, alt. 100 m, on 

 right bank of Rio Pacimoni, 50 km above mouth, 2 Oct 1958, Amazonas, Vene- 

 zuela, B Maguire & J. J. Wurdack 41677 (holotype NY, isotype US). Paratype. 

 Same locality, 41667. 



Distribution. This well marked species is presently known only from the 

 Pacimoni savannas. It is perhaps most closely related to X. uleana. 



7. Xyris uleana Malme, Repert. Nov. Sp. 3: 113. 1906. 



X. vaupesana Idrobo & Smith, Caldasia 6: 237. /. £6. 1954; type: Cano Pacu, Rio Vaupes, 

 Colombia, B. E. Schultes 5831 (US). 



Type. In arenosis humidis, Manaos, Amazonas, Brasil, May 1902, Vie 6171. 



Distribution. Guayana, chiefly on damp sand at low altitudes, on sandstone 

 areas up to alt. 1200 m ; Taf elberg, Suriname ; Kaieteur, British Guiana ; lower 

 Rio Negro, Amazonas, Brazil ; Vaupes, Colombia. 



The var. angustifolia Lanjouw, Kew Bull. 1939: 562 (1939) (isotype, Sand- 

 with 1421 [NY].), with narrow ("0.8 mm") leaves and subterete, hardly bi- 



