1953} 



BOTANY OF THE GUAYANA HIGHLAND 



117 



The flowers of both species are extremely interesting, for they appear to be 

 near to what must have been the primitive flower type in the genus. In three 

 species of the genus the stamens are equal, in contrast to the strongly dimorphic 

 androecium of most of the species. Equality of stamens may be interpreted as 

 more primitive than the dimorphic condition. S. fugax and the new species occupy 

 an intermediate position in this regard, for although the usual more massive sta- 

 mens can still be distinguished by their much stouter filaments, there is not the 

 sharp contrast between the larger and smaller stamens. In fact, in these two 

 species there is almost a complete gradation in stamen length and anther size 

 from the larger to the smaller. 



LEGUMINOSAE-P APILIONATAE 



Alexa superba Cowan, sp. nov. 



Arbor 5- 2D m. alta, ramulis puberulis; stipulae triangulares, acutae, 4 mm. 

 lcngae, 1.5 mm. latae, extus appresso-puberulae, intus glabrae, folia pendula, 

 imparipinnata, 15- 18-foliolata, petiolis 15-20 cm. longis, cum rachibus petiolu- 

 lisque aureo-fusco-puberulis, rachibus 43-67.5 cm. longis, petiolulis 7-11 mm. 

 longis, lamina 13-30 cm. longa, 5-9 cm. lata, foliorum basim versus minore, 

 oblongo-lanceolata, oblonga vel ovato-lanceolata, ad basim rotundata, ad apicem 

 acuminata, supra in costa valde puberula, alibi restricte ad sparse puberula, infra 

 aureo-pilosula, venis primariis in paribus 8-12, aeque cum costa leviter impressis 

 supra, infra valdissime salientibus, venulis supra obscuris, infra salientibus et 

 manifesto reticulatis; inf lorescentiae terminales, racemosae, 5-5.5 dm. longae, 

 fusco-puberulae, pedunculo ca. 25 cm. longo, 1 cm. diametro, bracteis caducis, 

 lanceolatis, 10-11 mm. longis, 4 mm. latis, aureo-sericeis sed intus restricte, 

 bracteolis lineari-1 anceo latis , 5—7 mm. longis, 1.5 mm. latis, intus glabris, pedi- 

 cello 9-10 mm. longo, 4 mm. diametro, fusco-puberulo; clayx campanulatus, 30-35 

 mm. longus, ad apicem 25 mm. diametro et incomposite sinuatus, extus dense 

 fusco-puberul us, intus ad apicem aureo-sericeus, petala 5, alutacea, extus densis- 

 sime aureo-sericea, intus glabra, cucullata, vexillo maximo, 7.8 cm. longo, L8 

 cm. lato, spathulato-oblanceolato, petalis reliquis aequalibus, 5o8-6 2 cm. longis, 

 ca. 1 cm. latis; stamina 12, glabra, filamentis 5-5.5 cm. longis, antheris lineari- 

 bus, 15-17 mm. longis, 1.5 mm. latis; (pistilli paulo post anthesin) stigma sim- 

 plex, stylus 30 mm. longus, glaber, ad apicem uncinatus, ovarium elliptico- 

 oblongum, 25 mm. longum, 7 mm. latum, aureo-pilosulum, valvis carnosis, 9-ovu- 

 lare, stipes 18 mm. longus, columnaris, aureo-pilosulus; fructus submaturus 25.5 

 cm. longus, 5 cm. latus, fusco-velutinus, stylo persistenti, ca. 32 mm. longo, 

 semina in pulpa sucosa immersa. 



TYPE: locally frequent tree 5-20 m. tall; petals apically cucullate, cream in- 

 side, golden brown sheen outside, one petal larger, margin of Cano Asisa (tribu- 

 tary of Rio Paru), near Puerto Camp, Territorio Amazonas, Venezuela, February 

 17, 1951 , Richard S, Cowan & John J. Wurdack 31531; New York Botanical Garden. 



Alexa superba is probably most closely allied to A. confusa Pittier from the 

 middle Rio Caura in Venezuela. This conclusion may or may not prove to be valid, 

 for I have seen material of only three of the six species previously described and 

 the opinion expressed is based largely upon the descriptions. A. superba differs, 

 first of all, from all the other species in the genus in its larger leaves with more 

 leaflets and in the presence of 12 stamens instead of the customary ten. In addi- 

 tion to these characters, the new species differs from A. confusa in the posses- 

 sion of pubescence on both leaf surfaces, a broadly campanulate calyx rather than 

 the narrow one of A. confusa; the calyx of the latter is glabrous within whereas 

 the apex of the calyx on the inner surface in A. superba is aureo- sericeous. 



