Rupert C. Barneby
Ebenopsis ebano (Berland.) Barneby & J.W.Grimes
2. Ebenopsis ebano (Berlandier) Barneby & Grimes, comb. nov. Mimosa ebano Berlandier, Mosaico Mexicano 4: 418. 1840 fide C. H. Muller, Phytologia 41(6): 386. 1979. — Original text not seen; lectotypus (Muller, 1. c.): s. loc., Berlandier 2262 (PH, herb, short.), the locality given on isotypus at F: "[El Encinal] de San Fernando à Santander [Tamaulipas, ±25°N] . . . 8bre 1830. Mexique." — Isotypi, G!, K! (see next entry), P!. — Chloroleucon ebano (Berlandier) L. Rico, Kew Bull. 46: 519. 1991.
Acacia flexicaulis Bentham, London J. Bot 1: 505. 1842. — "Texas, Berlandier. 2262." — Holotypus, K! = isotypus of the preceding. — Pithecolobium flexicaule (Bentham) Coulter, Contr. U.S. Natl. Herb. 2: 101. 1891. Zygia flexicaulis (Bentham) Sudworth, U.S.D.A. Div. Forest. Bull. 14: 248. 1897. Siderocarpos flexicaulis (Bentham) Small, Bull. New York Bot. Gard. 2: 91. 1901, nom. illegit. Samanea flexicaulis (Bentham) Macbride, Contr. Gray Herb., N. Ser. 59: 2. 1919. Ebenopsis flexicaulis (Bentham) Britton & Rose, N. Amer. Fl. 23: 33. 1928.
Hoopesia arborea Buckley, Proc. Acad. Nat. Sci. Philadelphia 1861: 453. 1862, ex parte, exclus. flor. caesalpiniaceo. — Equated by Bentham, 1875: 514, with Acacia flexicaulis, but based on a mixture, the essential character referable mostly to Cercidium.
Pithecolobium texense Coulter, Contr. U.S. Natl. Herb. 1: 27. 1890. — "[Nealley] 153 .. . Near Rome (Starr Co. [Texas])." — Holotypus, US 15159!. — Equated with P. flexicaule by Coulter, 1891,1. c.
Calliandra geniculata Wendland ex Bentham, Proc. Linn. Soc. London 30: 514. 1875, pro syn. (cult.).
Pithecolobium flexicaule sensu Sargent, Silva 3: 137, t. 147. 1892; Man. trees 538, Fig. 445. 1905 & ed. 2, p. 598, fig. 540. 1922; Standley, 1922: 396.
Pithecellobium flexicaule sensu B. L. Turner, 1959: 28, map 2, (Texas); Pennington & Sarukhan 1968: 184 & fig.; Isely, 1973: 114, map 38 (Texas); Vines, Trees of E. Texas 255 & fig. 1977.
Microphyllous, drought-deciduous trees commonly 2-8 m, with 1-several trunks 1.5-4 dm dbh but in undisturbed valley woodland attaining a height of 20 m and girth of 1 m, the bark fissured and flaking, the coarse stiffly flexuous branches armed at most nodes with a pair of straight ascending, ligneous, distally purplish-black or -castaneous and lustrous stipules subtending the primary lvs of long- shoots, most lvs fasciculate on scaley brachyblasts, the foliage appearing glabrous but the lf-axes and exceptionally also the plane, thinly papery olivaceous lfts thinly ciliolate with pallid hairs <0.25 mm, the amentiform spikes of small greenish ochroleucous, fragrant fls fasciculate on brachyblasts, mostly shorter than associated lvs. Stipules of primary lvs 2-10 mm, narrowed upward from ultimately swollen base into a vulnerant tip, those of verticillate lvs much shorter, imbricate. Lf-formula (i-)ii(-iii)/4-6; lf-stks 7-25(-28) mm, the petiole 3—14(—17) mm, at middle 0.4-0.7 mm diam, the longer interpinnal segments 4-11 mm; nectary between each pair of pinnae stoutly stipitate, in profile 0.45-1 mm tall, the shallow-cupular head 0.3-0.65 mm diam, no nectary at tip of pinna-rachises; pinnae when more than 1 pair accrescent distally, the rachis of furthest pair 11- 27(-33) mm, the longer interfoliolar segments (2.2-)3-7 mm; lft-pulvinules 0.25-0.4 x 0.3-0.5 mm, finely wrinkled; lfts opposite, accrescent distally, the blade oblong or bluntly rhombic-oblong from semi-cordate-auriculate or asymmetrically shallow-cordate base, broadly obtuse or widely emarginate, the penultimate pair 7-16.5 x 3-6(-6.4) mm, (1.8-)2.1-2.9 times as long as wide; venation palmate, of (3-)4— 5(-6) nerves from pulvinule, the open, often somewhat sinuous midrib a little forwardly displaced from center, V-forked well beyond midblade and usually not quite reaching the blade-apex, the inner posterior primary nerve produced to anastomosis at or well beyond midblade, the outer ones progressively shorter, the stronger primary nerves weakly branched and connected by random feeble tertiaries. Fl-spikes including peduncle 2-4.5(-5) cm, densely yellowish- or sordid-puberulent overall, the rachis compressed, the fls either subcontiguous or well-spaced; bracts ovate 0.4-0.8 mm, tardily deciduous; perianth 5- merous or the calyx randomly 4—7-merous, the latter puberulent overall, the corolla sometimes glabrate proximally but always puberulent on lobes; calyx hemispherical 0.8-1.2 x 1.1-1.5 mm, bluntly ribbed, the depressed-deltate teeth 0.2-0.4 mm, one sinus sometimes recessed almost to base; corolla funnelshaped 3.3—4.6 mm, the ascending lobes ±1-1.5 x 0.7-1.2 mm; androecium (34-)42-66-merous, (6.5-) 7-19 mm, the stemonozone 0.4—0.6 mm, the tube 3-4 mm, the callosities at base within 0.2-0.25 mm tall, sometimes poorly developed; ovary 1.1-1.4 mm, cuneately contracted at each end, at base into a stipe ±0.3 mm, at anthesis either glabrous or microscopically papillate, puberulent after fertilization. Pods almost always solitary, of slow maturation and hanging on the tree for nearly a full year, in aspect recalling the fruit of tamarind, sessile or almost so, compressed- sausagelike, straight or gently decurved, abruptly apiculate, when well fertilized 9-19 x (1.6—)1.8—3 cm, 9-17 mm thick, the broad sutures immersed, the woody valves ±1.5-2.5 mm thick, produced between seeds as pithy septa, rough and densely minutely brown-puberulent externally, appearing fuscous (or blackish)-felted, when weathered breaking into a mosaic of small tesserae; dehiscence very tardy, after falling, the valves at first separating at each end of pod, not or scarcely gaping, finally separating their whole length; seeds obliquely descending on filiform, straight funicles, plumply oblate-spherical or obtusely rhomboid 10-15 x 9.5-10 x 6-8 mm, the red- brown smooth testa 0.6-0.9 mm thick, closely investing the lentil-like pallid embryo, consisting of a thin outer coat becoming translucent when soaked, a thin crustaceous undercoat, and a much thickened fuscous or blackish endotesta, the not quite complete pleurogram 8-11.5 x 6.5-9.5 mm.
In thickets and subtropical deciduous woodland, on caliche and gritty clay soils of upland hillsides and sometimes on richer soils of river bottoms, mostly below 500 m, locally plentiful in NE Mexico (Tamaulipas and adjoining states) and SE Texas (N to the Nueces valley); disjunct and local in Yucatán; cultivated in S Texas, Florida, and elsewhere. — Map 47. — Fl. V—VII(XII). — Ebano (Mexico); Texas ebony (U.S.A.), acte (S. L. Potosí, Huasteco).
Stiffly flexuous branches, spinescent stipules, characterisitc leaflet-venation (see description), and spicate units of inflorescence arising from scaly brachyblasts identify E. ebano at anthesis, and the woody pod is unmistakable. The fruit ripens slowly and has been described as indehiscent or almost so, but after falling the valves in fact separate their whole length into a pair of boat-shaped vessels that spill the seed on the ground. Texas ebony is most commonly seen as a shrubby treelet, dark green when foliate, forming thickets in thorn-scrub and chaparral on impermeable caliche substrates, but Isely (1973) reported that in rich bottomland it can attain a stature of 20 m. The hard wood is used for fenceposts and in Mexico provides excellent charcoal.