Chloroleucon mangense (Jacq.) Britton & Rose
-
Authors
Rupert C. Barneby
-
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.
-
Family
Mimosaceae
-
Scientific Name
-
Type
"In insulis Caribaeis vicinaque Americes continenti.", elaborated in Select. Stirp. Amer. Hist. 2(qu): 267. 1763 & ibid. (fol) t. 262, fig. 70. 1781. — "Habitat Carthagenae, frequens in insula Mango [= Isla Manga, today a suburb of the city of Cartagena,
-
Description
Species Description - Wide-crowned, drought-deciduous trees and arborescent shrubs, at maturity (2)3-8 m, with smooth bark peeling in flakes and densely lenticellate annotinous branchlets, randomly armed with solitary or rarely geminate, divergent, tapering and vulnerant thorns to ±0.6-2.5 mm, very variable in lf-formula and in pubescence, either glabrous throughout or the lfts pilosulous with fine white, loosely spreading- ascending hairs to 0.15-0.4 mm, the hemispherical capitula of narrow whitish or greenish white fls expanding coevally with new foliage at lowest nodes of new branchlets, the lvs at anthesis commonly not fully expanded (membranous, smaller than at maturity), usually a little paler beneath than above; perulate buds axillary to older lvs ovoid 1.5-5 mm, their scales glabrous dorsally, striate-nerved, often microscopically ciliolate, each deciduous from a linear, transversely semiamplexicaul scar. Stipules at foliate and floriferous nodes commonly obsolete, when present submembranous, linear or narrowly oblanceolate- elliptic, 5-13 x 0.5-4 mm, the blade finely nerved, quickly deciduous. Lf-formula ii-ix/4—25(-29), the numbers more exactly given under each variety; lf-stk of mature lvs (0.5-)2-9.5 cm (of lvs coeval with fls, no further described, often shorter), the petiole proper (8-)9-24 mm, the longer interpinnal segments 6-20 mm; a convex nectary variable in form either near midpetiole or well below it, either sessile or shortly stipitate, 0.2-0.8 mm tall and 0.3-1 mm diam, similar but smaller nectaries on some distal segments of lf-stk and yet smaller ones at tip of each pinna-rachis; pinnae usually subdecrescent proximally, the rachis of distal ones 2.5-7 cm, the longer interfoliolar segments 0.8-17(-22) mm; lfts linear to broadly obovate or oblong-elliptic, the largest of a plant (always disregarding the proportionately broader furthest pair) 3.5-22 x 1-14 mm, 1.4-5 times as long as wide; venation of (2)3-5 primary nerves from very short pulvinule, the midrib subcentric to displaced to divide blade to ±1:2, either straight or less often distally curved forward, on each side 2-5-branched, the inner posterior primary nerve brochidodrome usually well above midblade, the outer ones very short, a tertiary venulation or reticulum developed in broader lfts, all venation sharply prominulous beneath, less so or immersed above. Peduncles solitary or paired with a thorn in the first 1-3-foliate axils of each new branch- let, (7-) 10-30 mm, very slender at anthesis, much thickened in fruit; capitula 15—30-fld, the fls erect- ascending, the receptacle becoming 1-3 mm; bracts commonly rudimentary or absent, exceptionally membranous, spatulate-oblanceolate to 1.6 mm; fls dimorphic, 1-3 central ones not or scarcely longer than the rest but their androecium much modified; perianth of all fls glabrous except for always densely pallid-papillate margin of corolla-lobes, or the calyx, rarely the corolla also, thinly pilosulous; PERIPHERAL FLS: perianth 5-merous; calyx narrowly campanulate 1.7-2.8 x 0.8-1.2 mm, the ovate-deltate teeth 0.2-0.5 mm; corolla 4.4-7.3 mm, the tube 0.8-1 mm diam, the ovate lobes 0.8-1.5 mm, their slender midrib once or twice branched; androecium 10-18- merous, 12-18 mm, the tube 2.3-3.2 mm, free from and included within the corolla; TERMINAL FL(S): calyx and corolla not or scarcely longer but a little broader than in peripheral fls; antheriferous stamens no more numerous than in peripheral fls but the filaments united into trumpet-shaped tube 7-10 mm, its flaring orifice fimbriate with short sterile filaments; ovary of all fls truncate, glabrous; stigma slightly dilated, ±0.2 mm diam. Pods often solitary but sometimes to 5 per capitulum, sessile but basally attenuate, in profile broad-linear, nearly straight or falcately recurved (or equivalently contorted) through to 3/4 circle (but not spirally coiled), when well fertilized 8-26 x 0.6-1.5 cm, at first flat and thin-walled, becoming thicker and lignescent at maturity, the strong sutures either straight or undulately constricted between the seeds, the thin, reddish brown or greenish, always glabrous exocarp coarsely venulose, the crustaceous endocarp to 0.3 mm thick, internally mealy between seeds, these lying in discrete cavities; funicle filiform, coiled distally; dehiscence tardy, the sutures narrowly gaping but the seeds apparently released only by weathering on the ground, the valves also developing transverse fracture lines between seeds as though incipiently lomentiform; seeds either obliquely or sub- vertically descending, compressed-oblong-ellipsoid, in broad view 5.5-7.5 x 3-5.1 mm, smooth and pale fawn- or putty-colored, fuscous over the pleurogram, this elongately U-shaped 3.2-5 x 1.7-3 mm; seed-testa ±0.4 mm thick in section, composed of a thin translucent coat gelatinous when wetted and a hard impervious inner coat; no endosperm.
Distribution and Ecology - In deciduous and semideciduous, more or less xeromorphic woodland or chaparral at elevations mostly below 600 m, exceptionally to 1200 m, widespread in locally differentiated forms from the S margin of the Sonoran Desert in NW Mexico to Colombia, Venezuela and the Antilles, thence S along the E foothills and intermontane valleys of the Andes into NE Bolivia. Flowering with the flush of new foliage following rains, becoming leafless or nearly so in the dry season; filaments white on expansion, becoming ochroleucous or yellowish when faded.
-
Discussion
Excepting only the localized Cuban Ch. guantanamense we here include within Ch. mangense all segregates of Chloroleucon native to Mexico and Central America, Colombia and Venezuela, and the Antilles; and we further extend it to embrace Ch. mathewsii, found around the western edge of the Amazon basin in Peru, northeastern Bolivia, and adjoining Brazil. In continental South America north of the Amazon River it is the only species of Chloroleucon, other than Ch. foliolosum and Ch. eurycyclum, readily distinguished either by very numerous small leaflets or by tightly coiled fruit, or by both.
Within this extensive range of dispersal, the inflorescence of Ch. mangense remains monotonously uniform within a quite narrow size range, but there is conspicuous variation in pubescence of the leaves, in number of pinnae and leaflets per leaf, and in both length and width of fruit, which have consequences in width and length of interseminal septa and in orientation of the seeds. The variation in pubescence appears almost everywhere random and independent of other factors; despite the importance attached to it in the past, it has no taxonomic significance. Within each subunit of the species, such as occupies a phytogeo-graphically natural range and is in other respects uniform, there occur perfectly glabrous and more or less densely pubescent populations (or individuals). These are far from evenly distributed within the species as a whole: Cuban var. lentiscifolia, for example, is prevailingly glabrous but occasionally pilosulous, whereas the reverse is true of var. vincentis and var. leucospermum, and all known examples of var. mangense and var. mathewsii are pubescent to some degree. Length and width of the fully mature pod are, within narrow limits, correlated with dispersal. However, the length of the fjruit is not determined by number of ovules or seeds. In the long narrow pod of var. leucospermum the seeds are no more numerous than in the shorter and proportionately broader one of var. vincentis, but they stand further apart in narrower longer locules separated by distinct constrictions of the sutures. Because of vertical extension and horizontal constriction of the valves, the seeds are turned mechanically into a nearly vertical orientation. Number and reciprocally adjusted size of leaflets are the most obvious differences between geographic races of Ch. mangense, but care must be taken in interpreting the size. Stems collected when the flowers are in full anthesis normally bear only immature leaves, with small tender leaflets not yet fully expanded and materially different in size and texture from those of mature leaves coeval with the fruit. The smallest leaflets are linear, whereas larger ones vary imperceptibly from narrowly oblong to oblong-elliptic or obovate, and the venation increases in complexity with increase in size. Marked discontinuities in leaflet-shape between geographically vicariant varieties of Ch. mangense are generally lacking, but in conjunction with fruit characters the average leaf-formula is distinctive.
Geographically central to the species is var. mangense, characterized by high leaf-formula, narrow leaflets, and relatively broad pod with straight sutures. We hypothesize that in context of this species a multi- foliolate, microphyll leaf and a relatively wide pod with straight sutures are primitive features. Passing outward in any direction from the geographic center of the species one encounters progressively fewer leaflets, or narrower pods, or both, and the leaf- modification appears to have followed parallel courses in areas now distantly disjunct. On account of the parallelism, the identity of a given specimen of unknown origin may be unrecognizable by characters of the foliage, but easily known by the pod. The varieties of Ch. mangense with relatively low leaf-formula and broad leaflets are decisively distinguished from South American Ch. tortum and Ch. tenuiflorum only by straight or falcate but never spirally coiled pod.
Correlation between morphology and dispersal is so nearly perfect in Ch. mangense that we are led to interpret occasional discordant records as due to dispersal by humans. The single records of var. leucospermum in Haiti and at the port of Kingston in Jamaica are examples. There are some genuinely puzzling intermediate forms, the identity of which we may have misinterpreted. Some plants from northern Falcón, Venezuela, and from Yucatán Peninsula seem intermediate between Cuban var. lentiscifolium and continental vars. vincentis and leucospermum respectively. An imperfect flowering specimen from Ecuador (Portovelo, perhaps = Portoviejo, but even the province unknown, J. N. Rose 23452, NY) is ambiguous between vars. mangense and mathewsii.
-
Distribution
Mexico North America| Cuba South America| Belize Central America| Guatemala Central America| Honduras Central America| Nicaragua Central America| Virgin Islands South America| Martinique South America| Saint Vincent and the Grenadines South America| Venezuela South America| Colombia South America| Ecuador South America| Peru South America| Bolivia South America| Acre Brazil South America| Jamaica South America| Panama Central America|