1963] 



BOTANY OF THE GUAYANA HIGHLANDS PART V 



227 



Gleason believed that the plants of his C. coriaceum had more broadly acute 

 and less narrowly pointed tips to the corolla-lobes than the narrower, more 

 attenuate apices found in the Roraima material of C. speciosum, but later 

 topotype collections of C. coriaceum from Auyan-tepui {Car dona 2669) and of 

 the nearby Chimanta Massif show as narrow corolla-lobes with as attenuate apices 

 as those of C. speciosum. Moreover, other collections from Chimanta show various 

 degrees of corolla-lobe width and apex attenuation. 



Most of the stipules and their prolongations are completely glabrous through- 

 out. A collection from Ptari-tepui (Steyermark 59740) has stipules strigose on 

 the upper margins and linear-cuspidate prolongations of the apex, but from the 

 same table mountain another collection (Steyermark 59801) varies from stipules 

 completely glabrous to strigose on the tips and upper margins on the branch on 

 the left hand side of the sheet in the Herbario Nacional of Venezuela. A topotype 

 of C. speciosum from Mount Roraima (Tate 388) also shows the stipule prolonga- 

 tion and upper margins sparsely strigose, while other collections from Roraima 

 (Steyermark 58860) exhibit both glabrous and sparsely strigose conditions. 



2. Maguireothamnus tatei (Standi.) Steyermark, comb. nov. 

 Chalepophyllum tatei Standi. Field Mus. Bot. Ser. 7: 380. 1931. 



This taxon varies principally in shape, base, and apex of leaf-blade. Two 

 variations may be recognized. 



Key to the Varieties of Maguireothamnus tatei 



Leaves cuneate or more or less narrowed at base, acute to acutish at apex, elliptic-oblong 



to lance-elliptic, 2%-5 times as long as broad. 2a. M. tatei var. tatei. 



Leaves rounded, or broadly obtuse at base, obtuse to somewhat rounded at apex, oval to 



broadly oblong, l%-2% times as long as broad. 2b. M. tatei var. latifolius. 



2a. Maguireothamnus tatei (Standi.) Steyerm. var. tatei 



Chalepophyllum tatei Standi. Field Mus. Bot. Ser. 7: 380. 1931. 



Distribution. Upper escarpments and summits of the sandstone table moun- 

 tains of Venezuela along the western axis of the table mountains in Territorio 

 Federal Amazonas from Cerro Sipapo (Paraque) south to Cerro Huahamacari. 



VENEZUELA. Amazonas : Mount Duida, summit of Peak no. 7; alt. 2130 m; 

 Aug 1928-Apr 1929, G. H. H. Tate 623 (holotype of Chalepophyllum tatei, NY) ; 

 Mount Duida, summit, slopes of ridge 25 ; alt. 1650-1800 m ; 4 ft high ; 26 Nov- 

 16 Dec 1928, Tate 427 (paratype of Chalepophyllum tatei, NY) ; Mount Duida, 

 summit; alt. 1650-1800 m ; Aug 1928-Apr 1929, Tate 1016 (paratype of Chalepo- 

 phyllum tatei, NY) ; Cerro Duida, southeastern-facing slopes along Cano Negro 

 (tributary of Cano Iguapo) ; moist exposed cliff-face with Brocchinia tatei; alt. 

 1515 m ; shrub 2-3 ft tall with erect rigid stems ; flowers very fragrant, white 

 on lobes, buff-greenish on tube ; leaves coriaceous, deep green above ; 25-26 Aug 

 1944, Steyermark 58030 (F, NY, VEN) ; Cerro Duida, summit; high moist ridge 

 top ; alt. 1820-2075 m ; 4 Sep 1944, Steyermark 58335 (F, NY) ; Cerro Huachama- 

 cari, Rio Cunucunuma ; frequent on summit of East Ridge ; alt. 1820 m ; wandlike 

 shrub to 1.5 m high ; flowers white ; 8 Dec 1950, Maguire, Cowan, & Wurdack 

 30058 (NY); Cerro Huachamacari, Rio Cunucunuma; frequent in cumbre; 

 alt. 1700 m; 4 Dec 1950, Maguire, Cowan, & Wurdack 29810 (NY); Cerro 

 Huachamacari. Rio Cunucunuma ; between Summit Camp and East Escarpment ; 



