Abarema brachystachya (DC.) Barneby & J.W.Grimes
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Authors
Rupert C. Barneby
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Authority
Barneby, Rupert C. & Grimes, James W. 1996. Silk tree, guanacaste, monkey's earring: a generic system for the synandrous Mimosaceae of the Americas. Part I. Abarema, Albizia, and allies. Mem. New York Bot. Gard. 74: 1-292.
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Family
Mimosaceae
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Scientific Name
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Type
". . in Brasilia." — Holotypus, G-DC! = F Neg. 6973.
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Synonyms
Inga brachystachya DC., Mimosa lusoria Vell.
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Description
Species Description - Macrophyllidious shrubs and treelets 1-3 m, the young branches, all lf-stks, and peduncles sordid- or rufous-pilosulous with incurved-ascending or spreading hairs to 0.2-0.4 mm, the chartaceous venulose bicolored lfts glabrous except for minutely ciliolate, loosely revolute margin, bright green or olivaceous and lustrous above, paler beneath, the short dense capituliform racemes solitary or 2-3-nate in the axil of contemporary lvs, or, by reduction of these forming a short terminal pseudoraceme. Stipules linear or linear-attenuate (1.5—)2—5 x 0.2-0.4 mm, caducous. Lf-formula iii—vi(—vii)/4—7(—10), the lfts of larger lvs (48-)76-164; primary lf-stks (4-)6-20 cm, the petiole proper (l-)2-4.5 cm, the longer interpinnal segments (l-)2-4.5 cm; lf-nectaries sessile, orbicular or variously crumpled and sometimes extended lengthwise, shallowly concave, usually pallid, the first (in random lvs wanting) situated immediately below insertion of proximal pair of pinnae and 0.8-1.5 mm diam, similar but mostly smaller ones at insertion of distal pairs of pinnae and lfts; pinnae decrescent proximally but either the distal or the penultimate pair longest, the rachis of these (4-)4.5-9.5 cm, the longer interpinnal segments 10-21 mm, a pair of minute paraphyllidia often present but caducous; lft-pulvinules in dorsal view 1-1.7 x 0.4-0.9 mm; lfts subequiform but accrescent distally, very obtusely rhombic from inequilateral base, obtuse or obscurely emarginate, the penultimate pair (18-)20-35 x (9-) 10—21 mm, the furthest pair to 2.5-4.5 cm; venation of a diagonal midrib slightly curved forward and pinnately branched throughout, the posterior nerve from pulvinule no longer than secondary ones, all these and a reticulum of lesser venules prominulous on both faces. Peduncles stout 4-15 cm; capitula ±20-45-fld, at full anthesis more or less hemispherical, the fls ascending and spreading on pedicels a little decrescent upward along receptacle, this becoming narrowly clavate and 5-11 mm; bracts oblanceolate ±1.5-2.5 mm, early dry caducous; fls dimorphic, the peripheral ones pedicellate, the terminal one sessile, the perianth of all 5-merous (random abnormalities), greenish white or ochroleucous, minutely puberulent overall; PERIPHERAL FLS: pedicel of lowest ones (1.5-)2.3-4.7(-5) mm; calyx turbinate-campanulate (2.3-)3.2-4.7(-5) mm, the obtusely triangular teeth 0.5-1.1 mm; corolla 6.4-9.7 mm, the lobes 2.3-3.2 mm; androecium white 32-56-merous, the longer filaments 24-42 mm, the stemonozone 0.9-1.5 mm, the tube 2.5-5 mm; ovary glabrous truncate; ovules 8-13; TERMINAL FL(S): pedicel subobsolete; calyx campanulate, 4-5.5 mm, the teeth 0.7-1 mm; corolla 8.5-12 mm, the lobes 2-2.6 mm; staminal tube as long as or to 2.5 mm longer than corolla. Pods of A. filamentosa, 14—16 mm wide; seeds of A. filamentosa, 7.5-8.5 x 6-6.5 mm, the pleurogram ±6 x 3.5 mm.
Distribution and Ecology - In restinga and brushy woodland along the Atlantic coast of S Brazil, below 100 m, locally plentiful in latitude 22°40'-25°30'S between Espírito Santo and Paraná. — Map 25. — Fl. IX-III(-V).
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Discussion
Abarema brachystachya, A. obovata, and A. filamentosa form a replacement series that runs northward in a narrow ribbon along the Brazilian coast from Paraná to El Salvador, but is interrupted in Espírito Santo, where the line turns inland into submontane woodland. This south-north sequence corresponds more or less exactly with a morphological cline expressed in leaf-formula and in size of leaflets, which are most numerous and smallest in A. brachystachya, fewest and largest in A. filamentosa, and of intermediate size and number in A. obovata. Taking into account only the larger, fully expanded leaves of any plant, we found in A. brachystachya 48 leaflets per leaf and upwards, in A. obovata 24 to 36 per leaf, and in A. filamentosa 24 or less. The smaller, more numerous leaflets tend to be rhombic in outline, the larger ones obliquely obovate. Leaflets of A. filamentosa are glabrous throughout, whereas those of A. obovata and A. brachystachya are at least finely ciliolate, and those of A. obovata often pilosulous on one or both faces.
The basionym Inga brachystachya was known by Bentham (1875: 583) to be a taxonomic synonym of Mimosa lusoria Vellozo, but following the so-called Kew rule, which recognized the first combination in the accepted genus, he treated the species as Pithecolobium lusorium, a name unacceptable under the present code.
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Distribution
Espirito Santo Brazil South America| Rio de Janeiro Brazil South America| São Paulo Brazil South America| Paraná Brazil South America|