1963] 



BOTANY OF THE GUAYANA HIGHLANDS PART V 



121 



mento 125 between campamento 125 to beginning- of dwarfed forest above bluffs 

 above waterfall, on NW slopes of Cerro Venamo. Steyermark d~ NUsson 136 

 (fr. NY) ; southeast -facing slopes of Ptari-tepui, Steyermark 59998 (fl. F), 

 vicinity of Santa Teresita de Kavanayen, 60921 (fl. F). 



From the flowering material at hand, I see no reason for this species to be 

 excluded from Xeetandra. It is one of the easier taxa to be distinguished because 

 of the thick, obovate leaves in the dried state, green-brown and often shining 

 above, brown beneath, clustered at the tips of exceedingly robust branchlets. 



Pleurothyrium panurense (Meissner) Mez, Jahrb. Bot. Gart. Berlin 5: 468. 1889. 



Xeetandra panurense Meissner in DC. Prodr. 15 1 : 157. 1864. 



Type. Prope Panure ad Rio Uaupes, Amazonas, Brazil, R. S. Spruce 2449, 

 Oct 1852-Jan 1853 (isotype. fl. NY). 

 Vernacular Name. Louro (Froes). 



Distribution. Tree or shrub, according to Mez, to 20 m. 35 cm in circum- 

 ference, occurring sometimes in clay-silicose soil on the banks of ravines along 

 the Rio Negro and tributaries in Amazonas, Brazil. BRAZIL. Amazonas: terreno, 

 argilloso-silicoso. mata, beira decorrego, Jauarete, Vaupes, Froes 21235 (fl. NT), 

 Iffanaos, 20526 (fr. NY). 



The infructescence and fruit of this species were unknown until the above- 

 cited collection was made. The stout infructescence is glabrescent, and has only 

 a single fruit, black in the dried state, ellipsoid, about 15 X 9 mm, subtended 

 by a cyathiform cupule about 10 mm long and 12 mm in diameter, the margin 

 thin and somewhat erose, the surface rough, with a few large (about 2-3 mm in 

 diameter), pale brown tubercles, seated on an expanded, obconic pedicel 8 mm 

 in length and o.mm or less wide at the apex. 



The dark, reddish-brown pubescent branchlets, the rather shining leaves with 

 stout midribs and 10-12 pairs of nerves impressed above and very prominently, 

 conspicuously elevated beneath are characteristic of the species. Particularly 

 noticeable is the regular pattern made by the confluent nerves near the margin 

 of the leaves, which is frequently characteristic of the genus. 



Pleurothyrium cowaniana, C. K. Allen, sp. nov. Fig. 59. 



Arbor parva ad 10 m alta, gemmis magnis ovoideis fulvo-tomentosis, ramulis 

 robustis conspicue striatis angulatis teretibus dense fulvo-tomentosis. Folia 

 magna, alternata, petiolis percrassis dense fulvo-tomentosis valde canaliculars 

 ad 2 cm longis et ad 5 mm latis. at videtur striatis. laminis supra glabris sub- 

 lucidis sparse papillosis, subtus sparse pubescentibus glabrescentibus, mem- 

 branaceis, ellipticis ad 35 cm longis et 14 cm latis, margine subtus utrinque dense 

 pubescentibus, ad basim obtuso-acutis vel subrotundatis. ad apicem abrupte 

 acuminatis, acumine tenui acuto ad 18 mm longo, et ad basim 7 mm lato, pen- 

 ninerviis, costa supra subplana. subtus crassa elevata pubescenti, nervis ± 15- 

 paribus plerumque tenuibus supra leviter impressis subtus elevatis pubescentibus, 

 ad angulo 50-45° divergentibus ad marginem confluentibus, rete venularum 

 utrinque laxo. nervis transversis gracilibus conspicuisque. Inflorescentia axillaris, 

 satis robusta, minute fulvo-tomentosa, racemoso-paniculata, ad 11 cm longa, 

 pedunculo ad 2.5 cm longo. Flores magni, ad 7 mm longi (post anthesin) pedicel- 

 lis ad 1.5 mm longis, perianthio campanulato vel suburceolato, eburneo-albo fide 

 coll., dense pubescenti, lobis crassis apice reflexis, exterioribus late ovatis, inte- 



