1953] 



REVISION OF MACROL OBIUM 



303 



21e. Macrolobium campestre var. longibracteatum Cowan, var. nov. Figure 7. 



Arbor parva, ramulis foliisque glabris. Petiolus 20-28 mm. longus, leviter can- 

 aliculars. Folia 2-3-jugata, paripinnata; rachibus 3~5 cm. longis, leviter canali- 

 culars. Foliola 6-11.5 cm. longa, 2.5-4.5 cm. lata, ovata, ovato-lanceolata vel 

 lanceolata, ad basim obtusa ad acuta, ad apicem acuminata. Inflorescentiae 16- 

 18.5 cm. longae, axe brevi-pilosulo; bracteis 10-12.5 mm. longis, lanceolatis, 

 acuminatis, brevi-pilosulis; bracteolis 8.5 mm. longis, 3 mm. latis, ellipticis, 

 acuminatis, extus pilosulis, intus glabris vel sparsissime brevi-pilosulis. Sepala 

 2-3.5 mm. longa, 1-2 mm. lata, lanceolata. Petali lamina 4 mm. longa, 6 mm. lata, 

 unguicilo 5 mm. longo. Ovarium 2-3 mm. longum, 1 mm. latum, glabrum, 3-ovula- 

 tum, gynophoro 1.5 mm. longo, puberulo. Fructus ignotus. 



Type Collection: A, Ducke 1242, "Entroncamento, Belem," Para, Brazil, June 

 1943 (HOLOTYPE MO, isotypes IAN, NY, US). 



Unquestionably, the relationship of this species is with M. arenarium, but this 

 pair of species is completely without ties to the other species of the genus. They 

 may be regarded as the two extremes of a distinct line of relationship from which 

 one group of unijugate species may have diverged. Macrolobium campestre ex- 

 hibits the following characters which amply distinguish it from its only certain 

 relative: (1) it has 2-3~jugate leaf blades, and (2) its bracts and bracteoles are 

 pubescent, on one side at least. 



Five subspecific taxa are recognized within this species and are here treated 

 as varieties. Though these are "definitely accepted by the author," there is the 

 realization that future collecting within the range of the species may very well 

 merge some of the less distinct of these. However, in view of the data available, 

 this disposition of the variants appears to be at least a practical solution to the 

 problem. 



Plants of the typical variety may be recognized by their shrubby habit, their 

 relatively broad leaflets and by their pilose bracts. Only var. arirambense ap- 

 proaches it in aspect and the latter (var. arirambense) has very elongate inflores- 

 cences, the axis of which is short-pilosulose and its branchlets are puberulous. 

 The relationship of the last-mentioned variety is much nearer var. longibracteatum , 

 from which it is distinguished by its puberulous branchlets, differently shaped and 

 smaller leaflets, longer inflorescences, and smaller bracts. The inflorescences of 

 var. longibracteatum and arirambense are considerably longer than in any of the 

 other varieties and are distinctly arcuate, suggesting that they may be pendent in 

 nature. 



Var. arboreum is quite distinct by virtue of its narrow leaflets ^hich are smaller 

 on the average than those of plants of the other varieties. It becomes a tree of 

 considerable proportions, attaining heights of 35 m. according to the field notes 

 of B. A. Krukoff. These characteristics and its longer, differently shaped bracts 

 serve to separate it from its nearest relative, var. medium. As the epithet of the 

 latter implies, this variety is transitional, between var. longibracteatum and ar- 

 boreum. Its shorter bracts, puberulous bracteoles and shorter inflorescences serve 

 to distinguish it from var. longibracteatum, 



22, Macrolobium arenarium Ducke, Arch. Jard. Bot, Rio de Janeiro 3: 101. 1922. 

 Figure 7. 



Low shrub to 2 m. tall, the branchlets and leaves glabrous. Petioles 9-17 mm. 

 long, terete. Petiolules 3-5 mm. long. Leaflets 5.5-10.5 cm. long, 3"5 cm. wide, 

 equilateral, ovate to oval, the base equilateral, obtuse, the apex abruptly acumi- 

 nate or subacuminate, the extremity obtuse to acute; costa strongly impressed on 

 the upper surface, salient beneath, the venules subobscure. Inflorescences 4-5.5 



