1961] 



BOTANY OF THE GUAYANA HIGHLANDS PART IV (2) 



SI 



This collection, from the type locality, is the first since the original collection. 

 21'. Macrolobium spectabile Cowan, sp. nov. Fig. 52. 



Arbor dumosa 4—7 m alta, ramulis cano-pubernlis, stipulis caducis non visis. 

 Petioli cylindrici apicem versus canaliculati, 18-25 mm longi, puberuli, rhachibus 

 cylindricis sed canaliculars, puberulis, 28-32 mm longis; foliola glabra, bijugata, 

 petiolulis 1.5-3 mm longis, laminis subcarnosis, discoloratis, conspicue venosis, 

 8-11.5 cm longis, 4.5-5.5 cm latis, late ellipticis, ad basim inaequilateraliter acutis, 

 ad apicem obtusis, costa venisque plus minusve elevatis in faciebus ambobus. 

 Inflorescentiae axillares, 12-23 cm longae, axe cano-velutino, bracteis percon- 

 spicuis, persistentibus, cano-velutinis, 14—17 mm longis, 4—7 mm latis, acuminatis, 

 ovato-lanceolatis ad lanceolatas, pedicello 3.5-4.5 mm longo, cano-puberulo, brac- 

 teolis persistentibus, acuminatis, anguste ellipticis, 8-10 mm longis, 3.5-4 mm 

 latis. Hypanthium 2 mm longum, glabrum. Sepala 4, maxima ex parte glabra sed 

 ad apicem ciliolata, oblonga, obtusa ad acuta, 4-4.5 mm longa, 1.5-2.5 mm lata; 

 petalum album, oblanceolatum, 13-15 mm longum, 6.5-7.5 mm latum, extus 

 glabrum (ad basim puberulum), intus villosum. Staminum filamenta rubra, 

 leviter villosa, 19 mm longa, antheris ellipticis, 1.2 mm longis. Stigira puncti- 

 forme, stylo filiformi, leviter villoso, 17 mm longo, ovario glabro basim versus 

 marginaliter puberulo excepto, 4 mm longo, 1.5 mm lato, anguste oblongo, gyno- 

 phoro 4 mm longo, puberulo. Fructus ignotus. 



VENEZUELA: Amazonas: frequent on lower slopes of granitic laja on right bank of 

 Rio Siapa, 8 km below Raudal Gallineta (about 100 river km from mouth), alt. 130-200 m; 

 bushy tree 4-7 m; petal white, filaments red; 20 Jul 1959, J. J. WurdacTc $ L. S. Adderley 

 43508 (holotype, US No. 2281741). 



The relationship of this truly spectacular species is with M. campestre and 

 M. arenarium, species of the eastern end of the Amazon Basin. It is nearest the 

 typical variety of M. campestre from which it differs in petiole length, sepal 

 number, size of the petal, size and vest it u re of the bracts, etc. It is so completely 

 different from other species of the genus in Venezuela that on first examination 

 one might not recognize its affinities. 



23'. Macrolobium acrothamnos Cowan, sp. nov. Fig. 55. 



Arbuscula 8 m alta, ramulis glabris, petiolo 12-14 mm longo, glabro, foliolis 

 unijugatis. Petioluli 3-5 mm longi, glabri ; laminae late ellipticae, 7-11 cm 

 longae, 4.5-7 cm latae, glabrae, inaequilateraliter acutae ad basim, ad apicem 

 rotundae emarginataeque, haud attenuatae apicem versus, costa plana sed venulis 

 leviter salientibus supra, infra costa et venulis conspicue salientibus. Inflores- 

 centiae 4-10 cm longae, axillares, glabrae, pedunculo 7-21 mm longo, bracteis 

 caducis, triangularibus, acutis, 1.5 mm longis latisque, pedicello 3-5 mm longo, 

 glabro, bracteolis persistentibus, crasso-carnosis, 0.8 mm crassis, glabris, obovato- 

 oblongis, rotundis ad apicem, 7 mm longis, 4.5 mm latis. Hypanthium 2.5 mm 

 longum, glabrum, stipite 1 mm longo, glabro, sepala 4, oblongo-ovata vel oblonga, 

 4.5-5 mm longa, 2.5-3.5 mm lata, obtusa, glabra; petali stipes 1.5 mm longus, 

 ad basim leviter pilosulus, lamina 5 mm longa, 6 mm lata, suboblata, ad basim 

 villosa intus, extus glabra. Filamenta 7.5-9.5 mm longa, villosa, ad basim 

 breviter connata, antheris 2.5 mm longis, 1 mm latis, oblongis, glabris. Gyno- 

 ecium glabrum, stylo 7.5 mm longo, ovario elliptico, ca. 2 mm longo, 1 mm lato. 

 Fructus maturus 9 cm longus, ca. 3.5 cm latus, oblongus, ad marginem dorsualem 

 anguste alatus, semina 2.5 cm diametro, lateraliter compressa. 



