Macrolobium brevense Ducke

  • Authority

    Maguire, Bassett, et al. 1953. The Botany of the Guayana Highland. Mem. New York Bot. Gard. 8 (2): 87-160.

  • Family

    Caesalpiniaceae

  • Scientific Name

    Macrolobium brevense Ducke

  • Description

    Species Description - Large tree 20-30 m. tall, the branchlets pilose and puberulous. Stipules 4.5 mm. long, caducous, subulate, acuminate, ciliolate. Petioles 2-4 mm. long, pilose or pilosulose. Leaf blades elliptic-oblong to oblong-lanceolate, 18-27-jugate, the pairs of leaflets 3-6 mm. apart; rachis 5.5-11.5 cm. long, the wings ciliolate, sparsely pilosulose on the upper surface, glabrous beneath, the axis uncinatepuberulous on the upper surface, sparingly pilosulose or glabrous beneath. Leaflets (1.5-)5-20 mm. long, 1-7 mm. wide, the upper ones minute, oblong, the base inequilateral, the upper side obtuse to cordate, the lower side subobtuse, the apex rotund, emarginate, minutely apiculate; upper surface glabrous except for arcuate or uncinate hairs on the costa, beneath glabrous or the costa with very few hairs; costa strongly salient, the venules obscure on the upper surface, subprominulous beneath. Inflorescences 2-5.5 cm. long, the axis densely short-pilosulose, the peduncle 2-3 mm. long; bracts 2 mm. long, 1 mm. wide, caducous, triangular, acute, glabrous within, pilosulose externally; pedicels 1.5-3 mm. long; bracteoles 5-5.5 mm. long, 2.5-3.5 mm. wide, oblong or oblong-obovate, subappressed flexuose-pilosulose and pilose on the outer surface, villose within. Hypanthium 1.5 mm. long, sessile, glabrous or sometimes with few hairs. Sepals five, 1.5-3 mm. long, 1-1.5 mm. wide, triangular-lanceolate, ciliate apically. Petal blade 4-5 mm. long, 3-4.5 mm. wide, orbicular, the claw 4.5-7.5 mm. long, glabrous within, villosulose externally. Filaments about 12 mm. long, villosulose in the lower part. Stigma simple or subcapitellate. Style about 15 mm. long, pilosulose basally. Ovary 2- 2.5 mm. long, 1-1.5 mm. wide, oblong to oblong-oblanceolate, 3-4-ovulate, marginally pilose, the lateral surfaces glabrous, the gynophore 2.5 mm. long, pilose, inserted at the base of the hypanthium. Fruit (submature) 13.5 cm. long, 4-4.5 cm. wide, oblong, glabrous, the carpophores about 10 mm. long, glabrous.

  • Discussion

    LECTOTYPE: A. Ducke (H.f.B.R. No.) 16946 (flowering portion), "Breves, aestuario amazonico, civ. Para, silva primaria circa campinam arenosam," July 1923 (deposited U, isolectotype US). The fruiting portion of this collection was collected in the same locality but on a much earlier date, December 1922. Both the flowering and fruiting material is considered to be representative of this species.

    The selection of a lectotype was necessary here because Ducke, in his original description, cited only a single collection, which under most circumstances would be considered as the holotype. However, it really included two collections, and the International Rules provide that in such a situation a lectotype must be chosen.

    The geographic distribution of this species is rather surprising but entirely understandable in a region so poorly known floristically. Its type locality is Breves (from which locality the specific epithet is drawn) in the mouth of the Amazon River and is known elsewhere only from Esperanca, Amazonas in the upper part of the Amazon Basin. It may be safely assumed that the range of the species is the length of the basin and simply has not been collected at stations intermediate between the two geographic extremes.

    Macrolobium brevense appears to be a phylogenetic node from which at least two divergent lines have originated. It apparently occupies an intermediate position between these two lines and M. gracile. It is most nearly allied to variety machadoense of the latter species, and of the species in the two related lines of relationship, it is undoubtedly most nearly related to M. hubenanum. From M. gracile var. machadoense, M. brevense may be most readily separated by the shape of the leaf blades and the pubescence of the inflorescence. It is amply distinct from M. buberianum by the glabrous bracteoles, longer pedicels, and persistent stipules of the latter species.

  • Distribution

    Additional Specimens: BRAZIL: Esperanca ad ostium flum.. Javary, Amazonas, Jan. 1942, Ducke 899 (F, IAN, MO, NY, US); Breves, civ. Para, Aug. 1926, Ducke (H.J.B.R. No.) 16946-A (F-frag., G, NY, P, RB, U, US). The latter collection has previously borne the number "16946" which is the number of the lectotype collection. The number has been emended to read as shown above to avoid future confusion.

    Brazil South America|