48 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



[VOL. 10 



daclc $■ Bunting 36569 ; common north side Savanna III, Nov 20, 1953, Maguire, WurdacTc <$• 

 Bunting 36605 ; Savanna III, Nov 20, 1953, Maguire, WurdacTc 4- Bunting 36610. 



Monotrema bract eatum is known only from the wet Yapacana Savannas, 

 where it occurs commonly, but is mostly confined to peripheral or scrub savanna 

 area. 



5. Monotrema affine Maguire, sp. nov. Figure 7. 



Herbae terrestres perennes, caudice erecto vel suberecto 2-5 cm alto; foliis 

 5-7 in quoque tempore, 30-50 cm longis ; vaginis 8-12 cm longis, ad basim 15-20 

 mm latis, nec equitantibus nec distiche dispositis; laminis 20-40 cm longis, 6-8 

 mm latis, glabris, gramineis, 9-13 nervatis ; foliis veteribus marcescentibus ; pe- 

 dunculis axillaribus 1 vel 2 per folium, 5-7 dm longis, ca. 1 mm diam., quadran- 

 gularibus, 6-costatis; capitulis solitariis, 12-15 mm longis; bracteis primariis 1-2, 

 ovato-lanceolatis, 15-20 mm longis, ad basim 6-10 mm latis, acutis, cum 9-13 

 nervis principalibus ; bracteis secondariis numerosis ca. 20-30 ferme spiculas sub- 

 tendentibus, bracteis oblongo-lanceolatis, 10-13 mm longis, 3-5 mm latis, margini- 

 bus scariosis, apicibus obtusis, minute aristatulis; spiculis 15-25, stipitatis, stipi- 

 tibus ca. 1 mm longis; bracteolis 5-7, 6-7 mm longis, aliquantum acutis; petalis 

 flavidis, 6-7 mm longis, unguibus ca. 2 mm longis, laminis lanceolatis acutis, 4-5 

 mm longis ; staminibus 6, antheris ca. 4 mm longis, ad basim 4-thecatis, uniporis, 

 poris oblique terminalibus ; ovario evidenter non maturo. 



Type : herbaceous perennial 5-7 dm high, bracteoles white, petals pale yellow, 

 frequent in sparse savanna bush, north edge of Savanna ITT, 125 m alt., Rio 

 Orinoco, Terr. Amazonas, Venezuela, Nov 20, 1953, Maguire, Wurdack c£ Bunting 

 36611 (holotype NY). 



Paratypes: Yapacana Savannas: herbaceous perennial forming hummocks in caatinga, 

 Savanna III, Dec 31, 1950, Maguire, Cowan #• Wurdack 30488 ; frequent, edge Savanna III, 

 March 17, 1953, Maguire 4' Wurdack 34535 ; perennial herb with yellow flowers, Savanna III, 

 March 17, 1953, Maguire Wurdack 34566 ; perennial herb 50-70 cm high,*outer bracts green- 

 ish, inner white, bearing straw-colored pale yellow flowers, occurring where Monotrema braatea- 

 tum & M. xyridoides grow together, occasional in Savanna III, Nov 20, 1953, Maguire, Wurdack 

 4r Bunting 36570 ; infrequent in open woodland near Savanna I, Nov 20, 1953, Maguire, Wur- 

 dack 4- Bunting 36607. 



There is suggestive evidence that Monotrema affine is a sterile hybrid between 

 M . bracteatum and M. xyridoides. In stature M . affine is usually somewhat larger 

 than either of the others. In floral characters it seems to be somewhat interme- 

 diate between them, but the bracteoles are scarious-margined, a character that 

 does not obtain in either of the other two. In material examined, no mature 

 ovary or seed was found, although pollen seemed normal. And finally, this 

 possible hybrid occurs only in the presence of the two suspected parents, so is 

 thus confined, so far as known, to the Yapacana Savannas, to which M. bractea- 

 tum also is limited. M. xyridoides is of more extended distribution, but in its 

 additional range occurs without the presence of either M. bracteatum or M. 

 affine. 



14. Potarophytum Sandwith, Kew Bull. 1939: 20. 1939. 

 Parophytum riparium Sandwith, Kew Bull. 1939: 21. 1939. 



Type : Kaiteur Falls, in deep shade by a stream in the forest, Potaro River, 

 British Guiana, at 400 m alt., Sept 5, 1937, Sandwith 1382 (holotype K). 



In addition to the type collection is the following: locally frequent in boggy 

 place along stream near Potaro River Landing, Kaieteur Plateau, May 11, 1944, 



Maguire & Fanshawe 23396. 



