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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN [Vol. 8, No. 4 



Slender tree 4-18 m. tall, the branchlets pilose. Stipules (3-)5-6 mm. long, 

 0.5 mm. wide, subulate, ciliolate. Petioles 1.5-3 mm. long. Leaf blades oblong or 

 oblong-lanceolate, (10-)15(-20)-jugate, the pairs (2-)5(-8) mm. apart; rachis (4-) 

 8(-11.5) cm. long, pilosulose. Leaflets (4-)10-l l(-22) mm. long, (2-)3(-8) mm. 

 wide, oblong, the upper side of the base subcordate to cordate, the lower side 

 acute, the apex rotund or rotund-truncate, refuse to emarginate, usually minutely 

 apiculate; upper surface usually generally pilosulose, or pubescent only at the 

 base and on the costa, or rarely completely glabrous, beneath generally pilose 

 with the apical-lateral surface of the costa more densely pubescent, sometimes 

 pubescent only on the upper half of the blade and the costa. Inflorescences 1-2 

 cm. long; bracts 1.5-2.5 mm. long, 1 mm. wide, triangular-lanceolate or triangular; 

 pedicels 1-3 mm. long; bracteoles oblanceolate, elliptic, or oblong, (5-)6.5-7.5 

 mm. long, (2-)2.5-3 mm. wide, acute to acuminate, pilosulose on the outer surface, 

 pilose within, sometimes sparingly so. Sepals somewhat dimorphic, the adaxial 

 pair triangular to lanceolate, 1.5-2 mm. long, 0.5-0.8 mm. wide, the others 2-3.5 

 mm. long, 1 mm. wide, lanceolate. Petal blade 2.5-4 mm. long, 3"5 mm. wide, 

 transversely oval to orbicular. Filaments 15-20 mm. long, villosulose basally. 

 Style 16.5-18 mm. long, villosulose basally. Ovary fusiform, villose marginally, 

 the gynophore 2-3 mm. long, villose, inserted at the base of the hypanthium. Fruit 

 (immature) 5.5-8 cm. long, 3-5 cm. wide, oblong-obovate, sparingly pilose mar- 

 ginally, the carpophores (8—) 1 1—16 mm. long, sparingly pilose. 



LECTOTYPE: R. Spruce 2659 (flowering portion), near "Panure," Rio Uaupes, 

 Brazil, Oct. 1852 (deposited K, isolectotypes G, GH, NY, P, US, W). Since a type 

 was not designated by the original author, one of the two collections cited by him 

 has been chosen as the lectotype collection. Even the lectotype sheet bears ma- 

 terial of two collections and the flowering portion alone is designated as the lec- 

 totype. The fruiting material is considered to be the same as the flowering and 

 was collected in January 1853 in the same locality. 



Additional Specimens: BRAZIL: Amazonas: upper Rio Negro, Camanaos, Sept. 1935, 

 Ducke 33 (A, F, MO, NY, US); circa Cachoeira do Mindu, Manaos, Dec. 1941, Ducke 855 

 (F, IAN, MO, NY, US); Esperanca, ad ostium flum. Javary, March 1942, Ducke 1025 (type 

 collection of M. tenue Ducke) (IAN, MO, NY, RB, US); Sao Paulo de Olivenca, April 1944, 

 Ducke 2093 (IAN); super Rio Negro, Camanaos, Nov. 1932, Ducke (H.J.B."r. No.) 23297 

 (RB, U, US); on plateau between Rio Livramento and Rio Ipixana, Municip. Humayta, Not. 

 1934, Krukoff 7197 (A, F, MO, NY, U, US); ad flum. Casiquiari, Vasiva et Pacimoni, 1853- 

 54, Spruce 3410 (F, GH, MO, NY, P, US, W). PERU: Dombey s.n. (P). VENEZUELA: San 

 Carlos de Rio Negro, Amazonas, March 1942, Williams 14630 (F, US, VEN). 



Vernacular Name: "cipoal" (Brazil). 



Of the specimens cited, Ducke 1025 should receive some special attention, 

 since it^is the type collection number of M. tenue Ducke. It has been included in 

 the typical variety in spite of some differences between it and the remainder of 

 the material. However, these differences are so minute and apparently insignifi- 

 cant that there appears to be no point in recognizing this variant as a distinct 

 taxon of any category. The rachis of the leaves is puberulous on the upper sur- 

 face instead of pilosulose, the bracts oblong-ovate instead of more or less tri- 

 angular, and the pubescence of the bracteoles and of the ovary margins is some- 

 what shorter. Considering the rather variable nature of these characters in this 

 species, it is impossible to maintain AL tenue even as a variety. 



Macrolobium gracile is a .rather polymorphic species, but the diversity in its 

 characters is not insoluble. It differs from M. brevense, its nearest relative, by 

 the pilosulose inflorescences, flexuose-pilosulose and pilose outer surfaces of 

 the bracteoles of the latter. The costa of M. brevense is strongly salient on the 

 upper surface, which is not true of M. gracile except in its var. machadoense and 



