Senna atomaria (L.) H.S.Irwin & Barneby

Authors

Howard S. Irwin, Rupert C. Barneby

Authority

Irwin, Howard S. & Barneby, Rupert C. 1982. The American Cassiinae. A synoptical revision of Leguminosae tribe Cassieae subtrib Cassiinae in the New World. Mem. New York Bot. Gard. 35, part 2: 455-918.

Family

Caesalpiniaceae

Scientific Name

Senna atomaria (L.) H.S.Irwin & Barneby

Type

Holotypus, LINN 528/17 (lvs only, ex hort. upsal.)!- Correctly equated by Britton & Rose, 1930, p. 269, with Cassia emarginata sensu Benth. et auct. posterior., non C. emarginata Linn., quae = Senna bicapsularis nob.

Synonyms

Cassia atomaria L., Cassia arborescens Mill., Cassia longisiliqua L.f., Cassia elliptica Kunth, Cassia grisea A.Rich., Cassia chrysophylla A.Rich., Cassia michoacanensis Sessé & Moc., Cassia emarginata var. subunijuga B.L.Rob. & Bartlett, Isandrina maxonii Britton & Rose

Description

Species Description - Xerophilous but not obviously xeromorphic, drought-deciduous, potentially arborescent shrubs or trees at anthesis (2-)3-17(-20) m, with 1-several gray or brownish trunks attaining 7-15(-?) cm diam and a rounded head of ill-scented foliage, the annotinous branchlets scaley and lenticellate, the hornotinous ones together with foliage and axes of inflorescence softly, often densely pilosulous or tomentulose with straight spreading, simply incurved or shorter, variously curly or even crimped hairs up to 0.2-0.6(-0.7) mm, the bicolored lfts dark olivaceous and dull or sublustrous above, pallid beneath, pubescent on both faces but more thinly and shortly so above, the lf-stalks and inflorescence nearly always charged with small thickened orange, erratically branched trichomes, the young vesture often lutescent fading whitish, the racemes arising either from a) leafless or depauperately leafy brachyblasts borne on otherwise leafless branches, or b) from brachyblasts lateral to branches leafy distally, or c) axils of ordinary foliage lvs, the inflorescence normally coinciding with renewed vigorous growth following rains, the foliage in actuality either syn- or hysteranthous, but mature lvs usually coeval with pods. Stipules erect, subulate, triangular-subulate or rarely setiform 1.2-4(-5) x 0.3-1 mm, firm, early dry stramineous, often but not always persistent after fall of lf, either pilosulous or glabrous dorsally, ± thickened at base and externally convex, superficially nerveless. Larger mature lvs (8.5-)10-24(-28.5) cm, those directly associated with fls or crowded on brachyblasts smaller in all dimensions (and not further described); petiole including firm discolored pulvinus (2-)2.5-6.5 cm, at middle 0.8-1.6 mm diam, terete except for 2 low thick ventral ridges; petiolar gland 0; rachis (0-)1.5-9(-11) cm, its longer interfoliolar segments 1-3(-3.4) cm; pulvinules (1.5-)2-5 mm; lfts (1-)2-5 pairs, accrescent distally, the distal pair broadly obovate to elliptic or less commonly ovate, when broadest beyond middle obtuse or emarginate at apex and either rounded or cuneate at the subequilateral base, when broadest near or below middle either obtuse or deltately acute mucronulate, the distal pair (2-)3-11(-13) x (l-)1.5-5.4(-6) cm, (1.4-)1.6-2.8(-3.2) times as long as wide, the margin strongly revolute, the midrib with 5-15 (commonly 6-11+ random intercalary) pairs of secondary camptodrome veins and a complex mesh of reticular venules all sharply prominulous (and often pallid) beneath, on upper face only faintly raised or mostly immersed, rarely engraved. Racemes commonly (3-)5-15(-18) but occasionally (in Jamaica, Hispaniola, Venezuela) 20-55-fld, 2-several simultaneously expanded fls raised ± to or above level of succeeding buds, the slender, when long pendulous axis together with short peduncle becoming (1.5-)2-7 (exceptionally to 11-17) cm; bracts ovate- or lance-attenuate 1.5-3.5 mm, early caducous; young fl-buds globose, pilosulous, puberulent or glabrate, the sepals separating before true anthesis; pedicels at anthesis subfiliform, in fruit much thickened (13-) 15-24(-28) mm; sepals greenish, fuscous or yellow and petaloid, well graduated, the small outermost ovate 2.5-4(-4.5) mm, the largest innermost one obovate, oblong-obovate or suborbicular (4.5-)5-7(-8) mm, all reflexed in late anthesis; petals rich orange-yellow drying bright or brownish yellow, delicately dark-veined, either glabrous or thinly pilosulous dorsally, the 3 adaxial and one abaxial (opposed to pistil) slenderly clawed and homomorphic except of different sizes, (7-)8- 16(- 17) mm long, the blades oblong-oblanceolate or -obovate, the vexillar petal usually shortest, either obtuse or retuse, the abaxial one longest, the fifth petal thick-clawed and abruptly incurved through ±90°, convex and folded over androecium, measured along falcate midrib (12-) 13-23 mm; androecium glabrous or the anthers more commonly thinly pilosulous with erect stiff hairs, the staminodes 1.2-1.6 mm wide, emarginate at both ends, the filaments subequal or the abaxial ones a trifle longer, the 7 fertile anthers yellow, isomorphic except the abaxial ones sometimes slightly longer, all narrowly oblong obcompressed (2.8-)3-4.7(-5) x (1.1-) 1.2-1.7(-1.8) mm, at apex bluntly truncate and incurved into 2 very short, latero-infraterminal separated beaks opening by a vertical slit, the whole anther sulcate lengthwise at the connective and carinate by the sutures, each theca obscurely sulcate proximally between suture and connective; ovary glabrous at anthesis, often permanently but sometimes becoming densely pilosulous following fertilization, the vesture persistent along the sutures and sometimes also the valves of the mature pod; style stout, gently incurved 0.9-1.8 mm, at conic tip 0.3-0.5 mm diam, the minute stigmatic cavity terminal glabrous; ovules 46-70. Pod pendulous, the stipe 2^4(-5) mm, the body elongately linear straight or almost so, strongly compressed but thick-textured, potentially 2.2-3.5(-3.7) dm long but often following abortion of some or many proximal or random distal ovules shorter or irregularly strangulated (or both), between the greatly thickened sutures (8-)8.5-12(-14) mm wide and at them 2-3.5 mm thick, the cross section narrowly oblong or coarsely I-shaped, the firm subsucculent green valves becoming woody, dark brown or blackish, prominently venulose, their incrassate margins splitting transversely, the interseminal septa lignescent, the seed-cavities 3-5.5 mm long, as wide as the valves, the whole pod long-enduring on the tree, falling indehisced except by transverse fracture through the septa, the seeds released only by trampling or rot of valves; seeds transverse, obovoid or oblong- obovoid, accommodating themselves to the width of the cavity and thus moderately compressed parallel to the valves or rarely subterete, 4.2-5.3 x (2.2-)2.7-3.6 mm, the testa light reddish-brown, smooth but not highly lustrous, the elliptic or broadly oblong areole 1.2-2.4(-3) x (0.6-)0.8-1.7 mm.-Collections: 265.

Distribution and Ecology - Thorn-forest, chaparral, tropical deciduous and semi-deciduous woodland and brush-savanna, locally surviving in xeric microhabitats (outcrops, barranca-terraces, stream-banks, coral reefs) within mesic climax associations, mostly 1-600 m but attaining 1000-1150(-1600) m in s. Mexico (Michoacan, Oaxaca, Chiapas), Honduras and n. Venezuela (Maracaibo Basin, Cordillera Costanera), interruptedly widespread and locally abundant over much of seasonally arid lowland Mexico, Pacific Central America, West Indies and n. South America: Pacific lowlands and foothills of Mexico and Central America from s. Sonora (lat. ±28°N) and s. Baja California Sur to n.-w. Costa Rica (Guanacaste, lat. ±10°N), in Mexico extending inland to Balsas Depression (in Michoacan and Mexico) and e. across the Continental Divide to the Papaloapan and Grijalva valleys in n. Oaxaca and and Chiapas, in Guatemala e. to rio Motagua; Gulf lowlands of e.-centr. Mexico in s. Tamaulipas, centr. Veracruz and immediately adjacent San Luis Potosi (lat. 19-23°30'N); Bahamas (Eleuthera); circum-Caribbean from Yucatan Peninsula through Greater Antilles to Puerto Rico (s.-centr. only) and, becoming rarer, around the Lesser Antilles to Guadeloupe, St. Vincent and Curasao; arid coastal n. Colombia from Bolivar to Guajira Peninsula; n. Venezuela from periphery of Maracaibo Basin e. to Nueva Esparta, Sucre and Monagas, thence s. locally to the lower Orinoco and Caronf valleys in Bolivar (Cd. Bolivar, Parque Caroni).- Fl. in Mexico and Central America primarily (I-)II-V, in West Indies primarily II-VIII, in South America primarily III-X, but sparse flowering with leaves erratic throughout the year except in extreme desert conditions, the fruit long persisting, often contemporaneous with new fls.

Discussion

Due to seasonal dimorphism, S. atomaria is not easily visualized through descriptions. A tree flowering at winter’s end from naked branches will be transformed in summer by a mantle of foliage sometimes mixed with erratic axillary racemes; while another may flower first from brachyblasts mixed with relatively small leaves destined not to attain their full amplitude until the pods begin to form. The species is most closely related to S. mollissima, which has the same long compressed many-seeded indehiscent pod but caducous stipules, all leaflets ovate-acuminate and all racemes axillary to coeval and ample leaves. In Pacific Mexico, where S. mollissima var. glabrata and S. atomaria are sympatric, the latter is easily distinguished by the pattern of inflorescence and the always 2-3 pairs of obovate (not 4-6 pairs of acuminate) leaflets; but in a wider view of these sibling species over their whole ranges these differential characters are fallible. Individual trees of S. atomaria in West Indies and Venezuela have many leaflets broadest below the middle and if not long-acuminate then distinctly deltate-acute at tip; others have many or all racemes pendulous and many-flowered from coeval leaf-axils, just like those of C. mollissima, although the individual flower is then smaller. Accompanying this small flower are generally shorter and slightly narrower anthers, and the seeds of S. atomaria are, so far known, a little smaller, as might be expected from the generally slightly narrower pod. Despite the fact that we have not found any one fully reliable diagnostic character, the identity of specimens is usually instantly clear and we have no difficulty in following tradition in the matter. A second close relative is the semiscandent S. peralteana, which see for comment. Within S. atomaria there is evidence of incipient racial differentiation coincident with dispersal. Mexican and Central American S. atomaria except for the populations in Yucatan, have in mature leaves only (1-)2-3 pairs of relatively large leaflets, the distal pair up to about 6-11.5 cm long, with 8-15 pairs of secondary veins, whereas the average mature leaf in West Indies, Venezuela and Colombia consists of 3-5 pairs of leaflets up to about 3-6.5 cm long, with only 5-9 pairs of secondary veins. Exceptions are relatively few and scattered: the Puerto Rican populations, for example, have few large leaflets of the Mexican type, unlike any in Hispaniola or Guadeloupe, as have a very few from northern South America; moreover starved foliage from Mexico may resemble in size if not in number of leaflets fully expanded foliage from the Antilles. It is possible that the Puerto Rican plant, curiously localized in a small area around Coamo, Salinas and Cayey, is an old introduction from the continent; if this could be proved, the separation of geographic subspecies might become justified, in which case the varietal epithet subunijuga would be available for the large-leaved Mexican and Central American form. A peculiar sterile specimen from Haiti (St. Marc, l’Artibonite, Leonard 2922, NY), left unnamed by Britton, is probably abnormal S. atomaria but is anomalous in having nothing but bifoliolate leaves. It may be juvenile, but field-observation is obviously indicated. The hard yellow wood of S. atomaria is gathered for fuel and formerly furnished a yellow dye. Animals feeding on the foetid foliage and firm fleshy pods are said to suffer loss of hair, as has been reported for the related S. haughtii in northern Peru. Senna atomaria often shares with the latter the curious development on the initially glabrous ovary of a fine pilosulous vesture that persists on the mature pod.

Common Names

Vara or flor de San Jose, alcaparro, barba de jolote, lengua de perro, chile perro, palo de zorrilla, p. hediondo, mora hedionda, patita, vainillo, arguchoco , chicha- rong, guncho , xtuab, xtuabin , Carbonera, canafistola ci- marrona, jupiter amarillo, guacamaya amarilla, yellow candlewood, bois cabrite, palo de chivo, p. de burro, sopalpo extranjero, velamuerto, chivato, chilmeto cuchillito, caraganito, jinnu, mora, Brusca, macho, Brusquillo, carangano, platanillo, tarantan, cacaíto, canafistol'in, mucutena extranjera

Distribution

Michoacán Mexico North America| Oaxaca Mexico North America| Chiapas Mexico North America| West Indies| Sonora Mexico North America| Baja California Sur Mexico North America| Guanacaste Costa Rica Central America| Michoacán Mexico North America| México Mexico North America| Tamaulipas Mexico North America| Veracruz Mexico North America| San Luis Potosí Mexico North America| Central Eleuthera Bahamas South America| Nueva Esparta Venezuela South America| Sucre Venezuela South America| Monagas Venezuela South America| Bolívar Venezuela South America| Puerto Rico South America| Saint Vincent and the Grenadines South America| Curaçao South America| Guadeloupe South America|