1958] 



THE BOTANY OF THE GUAYAXA HIGHLAND ] 



PART III 



97 



The three postulated relatives of R. virgata are well-branched shrubs with 

 moderately to densely setose hypanthia and bitubereulate ventral stamen con- 

 nective bases; all have glandular-puberulent or glandular-setose ovary apices. 



Rhychanthera grandiflora (Alibi.) DC. 



fihyncanthera intermedia Ule, Xotizbl. Bot. Gart. Berlin 6: 348. 1915. 

 Ehyncanthera orinocensis Sprague, Trans. Proc. Bot. Soc. Edinb. 22: 431. 1904. 



Gleason (Brittonia 1: 134. 1932.) pointed out the variability in cauline 

 pubescence to be found in the British Guiana specimens of R. grandiflora. Col- 

 lections since 1932 have obscured the lines between the "well-marked" forms 

 noted by Gleason. Both Ule's and Sprague 's collections (as represented at Kew) 

 are so similar as to appear parts of the same collection number ; both have long- 

 pilose stems. As suggested by Gleason. R. acuminata Benth. and R. betulifolia 

 Cogn., upon comparison with presently available collections, will probably fol- 

 low E. intermedia and R. orinocensis into synonymy. 



R. grandiflora is perhaps the commonest shrub in the Venezuelan morichales 

 and is also frequent in moist areas along- roadsides in the llanos. Plants may be 

 found in flower at any time of the year, depending on the seasonal wetness of 

 the habitat. Successive rings of plants flower around a morichal as the water 

 level lowers during the dry season; each plant, as the water level drops, gradu- 

 ally defoliates and ceases flowering. Robust colonies grow in almost soilless but 

 seasonally moist depressions on the crystalline lajas at Puerto Ayacucho. 



As delimited in the past, the genus Potercmthera has been composed of three 

 discordant elements; the species of sect. Onoctonia are congruous with Acisan- 

 thera, the generotype seems to belong in the Tibouchineae as a monotypic genus 

 related to Acisanthera, and the remaining species are well placed in the genus 

 Siphanthera. These adjustments will be treated in detail in a future paper, 

 only one transfer beinu made at present to accommodate the discussion of a new 

 Venezuelan species of Siphanthera. 



Siphanthera foliosa (Naud.) Wurdack, comb. nov. 



Tulasnea foliosa Naud. Ann. Sci. Nat. III. 2: 143. 1844. 



Poteranthera foliosa (Naud.) Cogn. in DC. Monogr. Phaner 7: 121. 1891. 



Siphanthera cowanii Wurdack, sp. nov. 



A conffeneribus antherarum rostris brevibus insignibus differ! staminibus 

 minoribus quasi perfectis cum rostris evolutis. 



Herba supra ramosa ad 35 cm alta glabra (nodis et sinibus intercalycinis 

 exceptis) ; nodi interfoliares pauco-setosi, setis ca. 1 mm longis. Folia 10-30 X 

 0.5-2 mm linearia acuta apiculata sessilia margine integra (raro apicem versus 

 paucidenticulata). Inflorescentia laxe paniculata ; flores ad 1 cm pedicellati 

 4-meri. Hypanthium 1.2-1.4 mm longum (fructiferum maius). Sepala 2.5-3.0 

 XI .3-1.6 mm. ovato-deltoidea apice acuminata apiculata. sinibus intercalycinis 

 unisetosis seta 0.4-0.5 mm longa. Petala 2.5-2.7 X 2.2-2.5 mm, asymmetrice 

 obovata vel subrotundata, apice minute apiculata rotundata vel subtruncata. 

 Stamina antesepala : filamenta 2.4-2.5 mm longa ; thecae (rostro connectivoque 

 exceptis) 0.8-1.2 mm longae, oblongae, rostro 0.3-0.7 mm longo, minute (0.1 mm) 

 uniporoso, connectivo sub theca 0.2 mm producto basi truncato vix incrassato. 

 Stamina altemisepala : filamenta 2-2.1 mm longa; thecae (rostro connectivoque 

 exceptis) 0.7-0.8 mm longae, ovato-oblongae, rostro 0.3-0.5 mm longo, connectivo 

 sub theca 0.3-0.4 mm producto, basi truncato incrassato 0.3 mm lato. Stylus 



