1961] 



BOTANY OF THE QUAYANA HIGHLANDS — PART IV (2) 



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scarcely developed; future collections may well show this population to be 

 infraspeeifieally separable, but there seem to be no floral differences. The radiate 

 trichome branches of the British Guiana species generally are longer than in 

 M. diaphanea, but there is overlapping in this character. I was unable to see, 

 even in young buds of M. fanshawei, a calyptriform calyx such as is apparently 

 found in M. diaphanea; such an observation could be much more easily made 

 in the field on fresh material since the dense pubescence obscures all such 

 delicate features in dried specimens. 



Miconia argyrophylla DC. subsp. gracilis Wurdack, subsp. nov. 



Rami juniores obtuse quadrangulati, vetustiores subteretes. Inflorescentiae 

 ramuli ex axe primario graciles ad basim ca. 0.4-0.5 mm diam. 



BRAZIL: Amapa: Serra do Navio, frequent in lowland forest along trail to Rio Ara- 

 guary; tree 4 m tall, flowers white; 19 Nov 1954, B. S. Cowan 38428 (holotype, NY); Serra 

 do Navio, Cowan 38345, 38380 (paratypes). Para: Akarai Mts. in Rio Mapuero drainage, 

 A. C. Smith 2933; Akarai Mts., Imaibau hills, Guppy 533 (Brit. Guiana For. Dep. 7548) 

 (paratypes). 



SURINAME: Rikenau Hill No. 3, vicinity of Moengo, Cowan 38973 (paratype). 

 BRITISH GUIANA: basin of Essequibo River near mouth of Onoro Creek, A. C. Smith 

 2678 (paratype). 



In typical M. argyrophylla (including var. attcnuata Cogn.), the branches 

 are acutely quadrangular and the inflorescence branches 0.7-1 mm diam. 

 M. crassinervia Cogn. was placed by Cogniaux in sect. Chdenanthera; the Flora 

 Brasiliensis illustration shows anthers longitudinally rimose basally but not 

 apically. I have examined two sheets of the type collection (Riedel 1396, K, W) 

 and cannot distinguish them from Guiana specimens ascribed to typical M. 

 argyrophylla; the anther clef ting seems to be caused by drying and/or press- 

 ing, rather than a genetic mechanism, and occurs sporadically in Guiana collec- 

 tions of M, argyrophylla sensu Cogniaux. Martius synonymized M. stenostachya 

 DC. with M. argyrophylla and illustrated flowering material of M. stenostachya 

 (Nov. Gen. Sp. Plant. 3: fig 284). Unfortunately the type collection of M. argyro- 

 phylla is fruiting and I have not as yet been able to compare the holotype with 

 recent flowering material. So many Miconia species have the same gross aspect 

 as M. argyrophylla that the absolute synonymization of M. crassinervia is de- 

 ferred. 



Miconia cowanii Wurdack, sp. nov. 



M. lepidotae DC. affinis sed cum foliis proportionaliter angustioribus, pube 

 cinerea, antherarum connectivo subtus prominenter expanso. 



Sect. Miconia subsect. Seriatiflorae. Rami acute tetragoni cum petiolis foliis 

 subtus inflorescentiis hypanthiisque pube albido-cinerea stellato-lepidota dense 

 obsiti. Petioli 1-2.5 cm longi ; lamina vix coriacea 11-26 X 3-8.5 cm elliptica 

 apice graditer vel subabrupte acuminata basi acuta 5-nervata vel paulo (ad 3 

 mm) 5-plinervata nervis exterioribus tenuibus nervis secundariis supra vix 

 impressis subtus anguste elevatis nervis tertiariis subtus laxe reticulatis margine 

 integerrima supra glabra. Inflorescentia paniculata 12-28 cm longa cum ramulis 

 extremis secundifloris ; flores 5-meri sessiles. Hypanthium (ad torum) 1.9-2.1 

 mm altum ; calycis tubus 0.5 mm altus lobis 0.4 mm altis late deltoideis dente 

 inconspicuo extus ornatis. Petala 2.6-3.1 X 1.5-1.8 mm apice oblique rotundata 

 glabra eciliata. Stamina paulo dimorphica ; filamenta 2.2-2.5 mm longa. Sta- 



