Abarema longipedunculata (H.S.Irwin) 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
"Auyan-tepui, Estado Bolívar, Venezuela . . . a lo largo del Río Churún, vecindad del Campamento sur, sureste del ‘Second Wall.’Alt. 1690 metros, 3 May 1964, J. A. Steyermark 93316— Holotypus, NY! isotypi, F!, U!, US!, VEN!
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Synonyms
Pithecellobium longipedunculatum H.S.Irwin
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Description
Species Description - Macrophyllidious shrubs and trees 2-20 m, with densely rusty-tomentellous growing tips but early glabrate, the lvs bicolored, the coriaceous lfts dark green (when dry brown) and sublustrous above, paler dull (when dry tan) beneath, the capitula solitary and geminate in distal lf-axils, equaling or shorter than associated lvs. Stipules linear or linear-lanceolate 1.5-2.5 mm, early deciduous, absent from fruiting specimens. Lf-formula i-iii/3-5; lf-stks stout 0.7-5.5 cm, the petiole 0.7—2.2 cm, at middle 1.6—2.6 mm diam, the longer interpinnal segment(s) 0—1.8 cm; petiolar nectary between first pinna-pair sessile, round crateriform or shallow-cupular 2—3.5 mm diam, a similar one at tip of lf-stk and smaller, elliptic, shallowly concave ones at 1—3 further nodes of pinna-rachises; pinnae when more than one pair accrescent distally, the rachis of distal (or only) pair 4-7 cm, the longer interfoliolar segments 9-23 mm; para- phyllidia minute; pulvinules in dorsal view 1.6-3 x 1-1.5 mm, deeply cross-wrinkled; lfts distally accrescent, asymmetrically elliptic, oblong-, or obovate-elliptic from antically cuneate, postically rounded base, obtuse or obscurely emarginate, the larger ones 3.8-6.5 x 2-33.5 cm, 1.4-2 times as long as wide; the gently porrect midrib subcentric, the 9-12 pairs of major secondary nerves brochidodrome shortly within the thickened but scarcely revolute margin, the tertiary venulation weak and random, faintly raised on one or both faces of blade. Peduncles (3—)5—12.5 cm; capitula ±20-25-fld, the clavate receptacle 4-8 mm; bracts (caducous) not seen; fls (known only fallen) subsessile and obscurely pedicellate, probably dimorphic but the terminal one not observed, the perianth of peripheral ones 5-merous, densely brown-puberulent externally, the corolla more thinly so below the lobes; PERIPHERAL FLS: calyx narrowly campanulate 5-7.3 x 2-2.3 mm, the teeth 0.6-1.8 mm; corolla 8-9.5 mm, the lobes ±2 mm; androecium 30-36-merous, not seen complete and the color (probably white) uncertain, the stemonozone 1.2-1.8 mm, the tube 7-8.5 mm; ovary truncate and a trifle dilated at apex, glabrous; TERMINAL FL: unknown. Pods to 6 per capitulum, sessile or cuneately narrowed at base into an obscure pseudostipe, in profile linear, when well fertilized 7-10.5 x 1.3-1.7 cm, 10-13-seeded, gently evenly retrofalcate through less than ¼-circle, the piano-compressed leathery, glabrous reddish valves becoming low-convex over each developing seed, when dry fuscous, coarsely crossnerved and reticulate, framed by evenly arched or (peripherally) shallowly undulate sutures 1.6-2 mm wide, the endocarp internally orange-red at seed-cavities and pallid between them; dehiscence through both sutures, the valves narrowly gaping to release or coiling; seeds plumply oblong-ellipsoid, in broad profile ±8.5-10.5 x 5.5-7 mm, the thin testa whitish at base and thence translucent pale tan, loosely vesting the gray-blue embryo, pleurogram 0.
Distribution and Ecology - On rocky summits, on cliff ledges, and in zanjones of sandstone table mountains, at (1100—) 1400-2100 m, endemic to Venezuelan Guayana in state of Bolívar: Meseta Jáua, C. Auyántepui, and C. Venamo, to be sought on C. Guaiquinima and Chimantátepui. — Map 8.
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Discussion
The protologue of P. longipedunculatum pointed to P. marginatum and P. villiferum as its nearest relatives. The latter, also native but not endemic to sandstone table mountains of Guayana, differs obviously in softly pubescent hypophyllum of the leaflets and in pubescent ovary conical (not truncate) at apex. Because fruit and seed are still unknown in A. villifera, it was not included in the cladistic analysis, where A. longipedunculata is sister-group to the terminal containing A. floribunda and A. ferruginea. These together with A. gallorum form a clade united, in part, by the red or pinkish corolla and stamens.
Pithecellobium marginatum, superficially similar to A. longipedunculata in glabrous foliage and nearly straight pod, differs fundamentally in small long-pedicellate peripheral flowers and a pod that when ripe cracks transversely between seeds but does not dehisce conventionally through the sutures. Furthermore its pleurogrammic seeds are quite different from those of A. longipedunculata, which have a characteristic translucent, unmarked testa; and its lowland riparian habitat is further distinctive. It is referred herein to the genus Hydrochorea. Among the abaremas of the Guayana Highland A. longipedunculata is readily known by the combination of low leaf-formula, glabrous adult foliage, and gently falcate, not circinnate legume.
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Distribution
Bolívar Venezuela South America|