Samanea inopinata

  • Title

    Samanea inopinata

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Samanea inopinata (Harms) Barneby & J.W.Grimes

  • Description

    3. Samanea inopinata (Harms) Barneby & Grimes, comb. nov. Serianthes inopinata Harms, Notizbl. Bot. Gart. Berlin-Dahlem 11: 55. 1930. — "Brasilien: Kultiviert im Bot. Garten Rio de Janeiro unter dem Namen Pithecolobium saman (Oktober 1928 — A. Ducke n. 15248)." — Holotypus, †B, isotypi, K!, RB!, UB!. — Pithecolobium inopinatum (Harms) Ducke, Mem. Inst. Oswaldo Cruz 51: 426. 1953. Albizia inopinata (Harms) Lewis, Leg. Bahia 182. 1987.

    Pithecellobium nuriensis [sic] Irwin, Mem. New York Bot. Gard. 15: 107, fig. 4. 1966. — "Venezuela, Edo. Bolívar, between Rancho Alegre and base of cerro, on trail to Quebrada Cabeza Burro, 5 km east of Chicharras. J. A. Steyermark 89317." — Holotypus, NY (2 sheets)!; isotypus, VEN 58840!.

    Calliandra tubulosa Bentham, London J. Bot. 3: 101. 1844, ex parte, quoad Gardner 1280, exclus. lectotypo.

    Albizia sp. Lewis & Owen, Leg. Ilha de Maracá 43. 1989. — Spm. authent.: Lewis 1422 (K!, NY!), Ratter 5723 (K!, NY!).

    Macrophyllidious trees potentially attaining 40 m with trunk to 1.5 m diam, but commonly smaller, sometimes flowering as treelets 2.5 m, the annotinous branchlets becoming corky and fissured; in almost all aspects other than the distinctive fruits resembling S. tubulosa, the pubescence similar in quality and distribution, either pallid or yellowish, the dimensions of lf-parts and fls sometimes but not consistently greater. Stipules ±4-6.5 x 1-1.3 mm. Lf-formula iii— iv/3—5; lf-stk of lvs on flowering branchlets 12-20 cm (of lvs from sterile or juvenile stems, no further mentioned, to 45-55 cm), the petiole 4-8 cm, at middle 1.7-2.8 mm diam, the longer interpinnal segments 3-5.5(-6.5) cm; lf-nectaries of S. tubulosa, the petiolar one at or shortly above base of petiole 1.2-3.5 mm diam; rachis of distal pinnae 4.5-11 cm, the longer interfoliolar segments 1.7-3 cm; lfts at apex either broadly obtuse muticous, or obtuse mucronate, or low-deltate apiculate, the blades of the penultimate pair ±4-6 x 2.1-2.5 cm, the venation as in S. tubulosa. Peduncles 6.5-15 cm; capitula 12-20-fld, the receptacle including terminal pedestal 1.5-4 mm, interfloral bracts linear-oblanceolate 3-10.5 x 0.45-1 mm; PERIPHERAL FLS: pedicel of lower ones 4-9.5 x 0.4—1 mm; calyx 7-11 x 2.7-4 mm, the teeth up to 0.9-2.6 mm; corolla 14-18.5 mm, the lobes 3-6 mm; androecium 24-35-merous, 42-54 mm long, the stemonozone 2-3.5 mm, the tube 8-12 mm; ovary sessile, linear in profile, tapering into the style, densely silky-strigulose overall; TERMINAL FL: differentiated apparently as that of S. saman but not studied in detail. Pods 1-2 per peduncle, sessile or almost so, in profile broad-linear 11-25 x 1.5-3.5 cm, only a trifle compressed and 1-2 cm thick, straight or randomly bent sidewise but not arcuately recurved, girdled by prominent, dorsally either plane or shallowly sulcate sutures 4-6 mm wide, the densely puberulent, often subvelutinous valves closely and deeply transversely wrinkled from suture to suture, internally composed of crustaceous or ligneous endocarp 0.2-1 mm thick in section and alveolate pulpy (pitchlike) mesocarp 2.5-6 mm thick, the cavity divided by septa into 1-seeded locules 5-6 mm long; dehiscence 0; seeds resembling those of S. tubulosa.

    In forest, or southward in caatinga-forest, 100-710 m, discontinuously dispersed in E South America both N and S of the Amazonian Hylaea: in E Venezuelan Guayana (lower Río Paragua and Altiplanicie de Nuria in estado Bolívar) and adjacent Guyana (Kanuku Mts) and Brazil (Ilha de Maracá in N Roraima); and in E Brazil from centr. Maranhão to Pernambuco (Tapera) S to ±13°30/ in E-centr. Bahia (Maracás, Jequié, Jaguaquara); described from a tree, of unknown provenance, cultivated at Rio de Janeiro. —Map 36. — Fl. N of the equator III—V, in E Brazil X-III. — Saman (Venezuela); coronha (Roraima); casqueiro (Bahia).

    Samanea inopinata is a cryptic species, not certainly distinguishable at anthesis from the closely related S. tubulosa. The peripheral flowers of the capitula are potentially larger and borne on potentially longer pedicels, and the range in leaf-formula is narrower, but we have found overlap in all vegetative and floral characters that we have measured. The fruit, however, is instantly recognized, for the valves lack the continuous livid exocarp common to S. tubulosa and S. saman and instead are deeply and closely wrinkled horizontally from one suture to the other. Fruits of this sort seem to coincide with dispersal shown in Maps 35 and 36. In our assessment of allopatry we initially ignored flowering specimens, which are inherently ambiguous.

    In its two foci of dispersal, as described above, the flower is equally variable in size, but the pod appears to have diverged into two forms. In eastern Brazil (Mori 12191, NY; the cultivated type collection of Serianthes inopinata), the pod is about 3.5 cm wide and 2 cm thick, with pulpy mesocarp about 6 mm and ligneous endocarp nearly 1 mm thick in section. By contrast, the populations in and around the Guayana Highland (type collection of Pithecellobium nuriense; Lewis 1422, NY) have pods only 1.5-1.8 cm wide and 1-1.3 cm thick, with mesocarp 2.5-4 mm and thinner, crustaceous endocarpic walls about 0.2 mm thick in section. Lewis and Owen (1989: 43) discussed the problem, but postponed a taxonomic conclusion until the relationship between these plants and the true saman, which herein is considered irrelevant, might be clarified. If the apparent difference in fruit-size is confirmed by new collections from the northern and southern lobes of the range of S. inopinata, we would admit P. nuriense as varietally distinct. The disjunction in range is less compelling insofar as precedents of similar bifocal dispersal without morphological differentiation are well established: for examples in Caesalpiniaceae see Senna velutina (Vogel) Irwin & Barneby and Chamaecrista roraimae (Bentham) Irwin & Barneby, described by Irwin and Barneby (1982: 232, 669).