1953] 



REVISION OF MACROLOBIUM 



299 



18b. Macrolobium montanum var. potaroanum Cowan, var. nov. Figure 7. 



Arbor 10-13 m. alta, 1 dm. diametro, ramulis minute puberulis, glabrescenti- 

 bus. Petiolus 8-11 mm. longus, glaber. Folia 2-3"jugata, paribus 10-17 mm. sepa- 

 ratis; rachibus 15-32 mm. longis, glabris. Foliola 20-35 mm, longa, 10-20 mm. 

 lata, oblonga, obovata vel oblongo-obovata, ad basim inaequalia, basis superiore 

 latere cordato, inferiore acuto, ad apicem rotundata vel truncata, retusa, supra 

 glabra vel sparsissime puberula in costa, infra glabra; costa saliens ambobus 

 lateribus. Inflorescentiae 8 cm. longae, axe minutissime puberulo, pedunculo 1.5 

 mm. longo; bracteis L5 mm. longis, 1 mm. latis, triangularibus, ciliolatis sed 

 aliter glabris; pedicellus 4-5 mm. longus, glaber; bracteolae 8 mm. longae, 3.5 

 mm. latae, ellipticae, acuminatae, intus sparse pilosulae, extus glabrae. Hypan- 

 thium 2 mm. longum, stipite 0.5 mm. longo, glabrum. Sepala 3-3.5 mm. longa, 1- 

 1,5 mm. lata, lanceolata vel elliptica, acuta ad acuminata. Petali lamina 4 mm. 

 longa, 5 mm. lata, transverse ovale, unguicilus 5 mm. longus, auriculatus. Fila- 

 menta 21 mm. longa, glabra. Stigma simplex. Stylus 10.5 mm. longus, glaber. Ovar- 

 ium 2 mm. longum, 1 mm. latum, lineare, glabrum, 2-ovulatum, gynophoro 3.5 mm. 

 longo, glabro. Fructus immaturus 10 cm. longus, 2.5 cm. latus, oblongus, apicem 

 versus iatior, glaber, carpophoro 12-14 mm. longo, glabro, 1-3-seminifer. 



Type Collection: D. B. Fanshawe 764 (F.D. No. 3500), "83 miles Bartica- 

 Potaro Road," British Guiana, July 1942 (HOLOTYPE BGF). 



Additional Specimens: BRITISH GUIANA: 85 miles Bartica-Potaro Road, Not. 1947, 

 Fanshawe 2758 (F.D. No. 5557) (BGF, U). 



The diagnostic characters of this species clearly indicate its affinity with M. 

 microcalyx and M. urupaense. It differs from the first of these by its less strongly 

 dimorphic sepals, by its glabrous ovary, and its usually greater number of leaflets 

 per leaf. From M. urupaense it may be separated by its fewer leaflet pairs, by its 

 more or less pubescent bracteoles, and by its generally shorter, glabrous or bas- 

 ally villosulose filaments. 



The two varieties included in this species are separable by the shape of their 

 leaflets, length of their leaf rachises, size of their bracteoles, presence or ab- 

 sence of pubescence on the filaments, and by their geographic distribution. 



19. Macrolobium urupaense Hoehne, Comm. Linh. Teleg. Estrat Matto-Grosso, An- 

 nexo n. 5, Bot. pt. 12: 11. pi. 184. 1922. Figure 7. 



Shrub or small tree, the branchlets, leaves, and inflorescence glabrous. Peti- 

 oles 8-10 mm. long, canaliculate. Leaf blades 5-7-jugate, the pairs about 12 mm. 

 apart; rachis 5-8 cm. long, canaliculate-alate. Leaflets 15-45 mm. long, 10-20 

 mm. wide, oblong or oval-oblong, the base inequilateral, the upper side cordate, 

 the lower side obtuse, the apex rotund, emarginate; costa plane on the upper sur- 

 face, salient beneath, the venules obscure above, prominulous beneath. Inflores- 

 cence 5-6 cm. long (fide Hoehne); pedicels 5 mm. long (5-7 mm. fide Hoehne); 

 bracteoles 10 mm. long, 5 mm. wide, broadly elliptic, acute, glabrous. Hypanthium 

 1.5 mm. long, glabrous. Sepals five, the adaxial pair nearly completely united, 2.5 

 mm. long, 1.5 mm. wide, triangular, acute, the other sepals 5 mm. long, 2-2,5 mm. 

 wide, lanceolate, acute. Petal blade about 5 mm. long, 6 mm. wide, transversely 

 oval, the claw 5 mm. long, strongly auriculate. Filaments 25 mm. long (30-35 mm. 

 fide Hoehne), villose in the lower one-half or more. Style glabrous. Ovary 2.5 mm. 

 long (1.5 mm. fide Hoehne), 1 mm. wide, oblong, glabrous, 4-ovulate (3-ovulate 

 fide Hoehne), the gynophore 5 mm. long, puberulous, inserted at the top of the ad- 

 axial hypanthial wall. Fruit unknown. 



Type Collection: /. G. Kuhlmann 2029 (H.J.B.R. No. 7323), "Campos dos 

 Urupas, Rondonia, Cataqui-Iamain, noroeste de Matto Grosso," Brazil, Dec. 1918 

 (RB). 



