THE BOTANY OF THE GUAYANA HIGHLAND PART III 



67 



16. Leaves acute or sometimes rounded at the base, with short but definite 

 petioles 3-5 mm long ; margins of the hypanthium very thin, and in 

 anthesis abruptly and narrowly revolute; staminal ring glabrous. 

 18. Inflorescence glabrous, only the vegetative buds silky with appressed 

 white hairs ; leaves rigidly coriaceous, obtusely pointed ; inflorescence- 

 branches stout, the 3-flowered peduncles 0.7-0.8 mm wide. 29. M. ligustrina. 

 18. Inflorescence and branchlets sparingly pubescent with pale or reddish 

 erect hairs; leaves thin, papery when dry, acute or short-acuminate; 

 inflorescence branches slender, the 3-flowered peduncles less than 0.5 

 mm wide. 



19. Buds much darkening in drying; inflorescence densely pubescent, its 

 branches contrasting with the glabrous buds; leaves 5-10 cm long, 

 often 2.4-3 times as long as wide. 8. C. multiflora. 



19. Buds pale yellow brown in drying, not darkening; inflorescence 

 sparsely pubescent or almost glabrous; leaves 2.5-5.5 (-13) cm long, 

 about twice as long as wide. 5. C. florifcra. 



0. Plants mostly with larger and often acuminate leaves (8-15 cm long or more), 

 longer and/or slender petioles (6-10 mm long or more), and abundant pubescence 

 (flowers velutinous or canescent or abundantly appressed-pubescent if the leaves 

 and petioles are both shorter than above). 

 20. Buds glabrous without, the inflorescence glabrous or sparingly pubescent or 

 puberulent. 



21. Buds 4-5 mm long, closed, broadly obovoid or subglobose; plants coarse, the 

 leaves 14-22 cm long, with relatively short stout petioles 2.5-3.5 mm thick, 

 5 mm long; midvein flat or convex above; panicles about 15 cm long, nearly 

 glabrous; British Guiana. 30. M. macrophi/lla. 



21. Buds 2-4 mm long, with short separate and distinct calyx-lobes, mostly nar- 

 rowly obovoid; leaves 6-12 (-17) cm long, the midvein narrowly impressed; 

 panicles pubescent or puberulent, 3-10 cm long; petioles longer in propor- 

 tion, 4-10 mm long, transversely rimose and corky-thickened at least in the 

 proximal half, the outer layers separating and persistent. 

 22. Leaves elliptic-obovate, about 2.5 times as long as wide, acute at base; 

 lateral veins 8-10 pairs; inflorescence puberulent, branching somewhat 

 irregularly, forking and zigzag, with persistent short lateral branchlets; 

 bracts early deciduous ; British Guiana. 24. M. gleasoni. 



22. Leaves elliptic-lanceolate, 3-4.5 times as long as wide, acute to rounded 

 at base; lateral veins 20-25 pairs; inflorescence thickly and finely ap- 

 pressed-pubescent, the flowers mostly sessile along straight divaricate and 

 much elongated lower branches of the panicle; bracts somewhat persistent; 

 Amazonian Brazil to eastern Colombia and adjacent Venezuela. 



39. M. umiraticola. 



20. Buds markedly pubescent, canescent, velutinous or hirsute, the hairs usually 

 covering the entire bud but sometimes confined to the proximal half (the base 

 of the hypanthium) ; inflorescence with a covering of hairs like those of the 

 buds. 



23. Panicles 1-2 (-3.5) cm long (a " panicle" here refers to one of the paired 

 panicles arising from the one node of an abortive axillary axis, or the 

 opposite panicles from the lower nodes of a terminal axis) ; flowers 3-8 

 (in 1 species -20) in each panicle, sessile or short-pedicelled, clustered near 

 the end of a short unbranched peduncle or a few lateral or basal, the 

 lateral branches of the panicle mostly undeveloped (in 1 species known in 

 bud only, the lateral branched present, reduced). 



24. Panicles about 20-flowered (seen in bud only), 2 cm long, branched 

 from near the base, the longest internode 1 cm long ; peduncle almost 

 none ; panicle-branches coarsely and persistently bracteate ; buds 3-3.5 

 mm long, obovoid to subglobose, at least the base persistently ve- 

 lutinous with reddish-brown hairs ; British Guiana. 13. C. smithii. 



24. Panicles 3- to 8-flowered, most of the flowers clustered at the summit 

 of the pedicle 3-10 (-30) mm long, sometimes with a pair of very 

 short 1-flowered branches near the base or middle of the peduncle 



