1963] 



BOTAXY OF THE GUAYANA HIGHLANDS PART V 



223 



Other minor differences which may be pointed out are as follows : 



Exsertion of style: In true Chalepophyllum the style may be included within 

 the corolla-tube or at most only slightly exserted to about 2 mm beyond the 

 orifice of the corolla. In contrast, in Maguireothamnus the style is usually prom- 

 inently exserted a distance of often 10-17 mm beyond the orifice. 



Anthers: In Maguireothamnus the anthers are located in the uppermost part 

 of the corolla-tube near its orifice, whereas in true Chalepophyllum the anthers 

 are located about way up the corolla-tube. 



Inflorescence: In Maguireothamnus the flowers are solitary in the upper axils 

 and shortly pedicellate or subsessile. In true Chalepophyllum the flowers may 

 be solitary and shortly pedicellate or occur as 2-4 cymosely arranged at the 

 tip of elongated peduncles which may reach 6 cm in length. 



These essential differences may be summarized as follows : 



Capsule loculicidally dehiscent; stipule persistent, terminating in a prominent triangular- 

 subulate free portion 2-6 mm long; lateral nerves and veins absent or obsolete on 

 lower surface of leaves; bracts subtending flower conspicuous, foliose, 7-16 mm 

 long; upper part of style densely papillate; corolla showy, very large, the tube 

 mainly 5-12 (rarely 4) cm long; corolla lobes chiefly 2-5 (rarely 1.5) cm long; 

 corolla-tube not densely long-bearded within at orifice, the tomentum not attaining 

 the summit or evident on herbarium material ; no glutinous exudate present on stems, 

 leaves, or inflorescence. Maguireothamnus. 



Capsule septicidally dehiscent; stipule often deciduous, inconspicuous, broadly triangular, 

 and subacute ; lateral nerves and veins prominent on lower surface of leaves, the 

 veins elevated to form a tessellated, rugulose, areolate surface finely tomentulose; 

 bracts subtending flower inconspicuous, scarcely 1 mm long; style glabrous; corolla 

 relatively small, the tube 1-1.6 cm long; corolla-lobes 0.6-1.5 cm long; corolla-tube 

 densely bearded at orifice with elongated hairs up to 2 mm long and extending 

 beyond the orifice and evident in herbarium material; glutinous exudate present on 

 some part of petiole, stem, or base of inflorescence. Chalepophyllum. 



Key to the Species of Maguireothamnus 



Ovary (hypanthium) and capsule glabrous; calyx-lobes glabrous; mature capsule 20-25 

 mm long; seeds 4-5 mm long; plants of the eastern sandstone table mountains of 

 Venezuela in the state of Bolivar west to Auyan-tepui. 1. M. speciosus. 



Ovary (hypanthium) and capsule densely hispidulous; calyx-lobes sparsely to moderately 

 hispidulous-ciliolate ; mature capsule 13-15 mm long; seeds 2.5-3 mm long; plants of 

 the western sandstone table mountains of Venezuela in Territorio Federal Amazonas. 



2. M. tatei. 



1. Maguireothamnus speciosus (N. E. Br.) Steyermark, comb, now Fig. 76, A-C. 



Chalepophyllum speciosum N. E. Brown, Trans. Linn. Soc. II. 6: 33. pi. 5, fig. 10-17. 1901; 



Standley, Field Mus. Bot. Ser. 7: 381. 1931. 

 Chalepophyllum coriaceum Gleason, Brittonia 3: 192. 1939. 



Distribution. Slopes and summits of sandstone table mountains of Venezuela 

 from Mount Roraima and Serra do Sol on the east by the British Guiana and 

 Venezuelan frontiers respectively west to Auyan-tepui, in estado Bolivar. This 

 is the most widely distributed species of the genus. 



VENEZUELA. Bolivar: summit, Roraima; alt. 8600 ft; autumn 1898, 

 Mc Connell & Quelch 653 (photo of holotype of Chalepophyllum. speciosum, from 

 K at NY) - summit, Mount Roraima; flower large, buffy-white, with red outside 



