Cassia fastuosa

  • Title

    Cassia fastuosa

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Cassia fastuosa Willd. ex Benth.

  • Description

    11.  Cassia fastuosa Willdenow ex Bentham in Martius, Fl. Bras. 15(2): 95. 1870.—Typus infra sub war. fastuosa indicatur.

    Potentially massive trees with broadly rounded crown, reaching 40 m with trunk 1 m diam but commonly seen 8-18 m with trunk 1.5-6(-8) dm diam and sometimes as a precociously flowering treelet no more than 4 m, the older branchlets livid glabrate, prominently obtusangulate, the hornotinous ones with lvs (except for sometimes glabrate upper face of lfts) and axes of inflorescence all minutely pilosulous with fine incurved or curly hairs up to 0.1-0.25 mm, the emergent foliage sordid-tomentulose but early greening and when adult bicolored, the lfts then lustrous green above and paler beneath, the phyllotaxy spiral, the long loose racemes of large fragrant fls borne on a stiff tapering, geotropically arcuate axis either terminal to few-lvd branchlets or to leafless branchlets arising from annotinous wood, anthesis coinciding with or closely following leaf-fall and flush of new foliage.

    Stipules thinly herbaceous green 2-lobed, appearing lunately semi-elliptic and laterally attached below middle, there 2.5-5 mm wide, the obliquely lance-acuminate or -caudate lobes unequal, the ascending one (5-)7-14(-15) mm, the descending one 3.5-7(-10) mm, the whole blade in age delicately reticulate-venulose, deciduous long before the associated lf.

    Lvs 1-4, mostly ±1.5-3 dm, progressively longer and more complex upward along each branchlet; petiole including firm pulvinus 14-26(-32) mm, at middle 0.8-2 mm diam, openly shallowly grooved ventrally; rachis mostly ± 1-2.5 (rarely -3.4) dm, the lfts inserted alternately up to 9-19 mm apart on each side, the ventral groove continuous; pulvinules 0.8-2 mm; lfts on each side of rachis 9-12 in early lvs, in later ones 12-25(-29), slightly decrescent toward base and often also toward apex of lf-stalk, the larger lfts narrowly lance-oblong, oblong-elliptic or seldom narrowly oblong-ovate, obtuse apiculate or acute to acuminulate 3-6 x 1-1.5(-1.7) cm, 3-4.4(-5) times as long as wide, at inequilateral base cuneate or rounded proximally, rounded to truncate and obtusangulate distally, the (adult) margin revolute, the midrib impressed above, cariniform beneath, the 8-13(-15) camptodrome with random intercalary secondary veins becoming finely prominulous on both faces, a faint open tertiary venulation either prominulous on both faces or dorsally only, or sometimes fully immersed.

    Racemes subsessile, openly (15-)20-35-fld, the axis with short or obsolete peduncle 15-35 cm, fully grown before the subsimultaneous anthesis of all its fls, these borne on stout, widely divaricate or recurved pedicels (2.5-)3-5.5(-6) cm, the pedicels when recurved also twisted to restore the fl to vertical; bracts herbaceous lance- or narrowly ovate-acuminate or -caudate 6-12 x 2-4 mm, persistent at least into early anthesis, then deciduous; bracteoles (basal or exceptionally shortly displaced upward along pedicel) similar to bracts but shorter and somewhat more persistent; fl-buds obovoid-ellipsoid, densely minutely velvety-puber- ulent; hypanthium narrowly vase-shaped (2.5-)3-5 mm; sepals firm, greenish or fuscous, convexly ovate-obovate, scarcely graduated in length, the longest 9.5-14(-15) mm, all promptly deciduous; petals golden yellow, widely expanded and almost plane, persistent beyond fall of sepals and androecium, subhomo- morphic, broadly obovate beyond the conspicuous claw, the longest petal (23-)25-37(-39) x 13-26 mm, the claws 2.5-6; androecium glabrous except for sometimes puberulent fertile anthers, the sigmoid filaments of 3 long stamens strongly dilated ribbonlike (33.5-)35-62 mm, of the rest porrectly erect, diminishing backward toward the vexillum, of 4 fertile ones 7-18 mm, of 3 adaxial sterile ones 5.5-14 mm, the antesepalous pair of the latter hamately recurved at apex; anthers of 3 long stamens ovate obtuse 2.5-4.5 x 1.8-2.2 mm, of 4 fertile median ones (4-)4.4-6 x 1.6-2.5 mm, of 3 adaxial sterile ones 0.5-1.7 mm, that of the antevexillar one larger than that of its neighbors; ovary densely loosely pilosulous, the stipe 4-6(-8) mm, the style (little differentiated externally) 2.5-3.5 x (0.55-)0.6-0.75 mm, the minute intro-antrorse stigmatic cavity ±0.2 mm diam; ovules 162-234.

    Pod pendulous, narrowly rod-shaped, when fully fertile 40-70 x 1.1-1.35(-1.65) cm, bluntly bicarinate both dorsally and ventrally by parallel contiguous, low-prominulous stout ribs 1-2 mm diam, convex laterally, the cross section oblately elliptic, the thin pithy exocarp either early glabrate or densely persistently velvety-puberulent, transversely cracked when dry, the thinly woody but rigid endocarp 0.3-0.4 mm thick, the wall of the septa slightly thinner, the locules 3-3.5 mm long, occupying the whole width of the cavity; seeds turned broadside to the septa enveloped in gelatinous, when dry flaky pulp, in broad outline obovate 5.5-8 x 4-5.5 mm, the testa smooth castaneous lustrous.

    The sumptuously large-flowered C. fastuosa, during its short flowering season the handsomest of the Amazonian true cassias, is closely related to C. ferruginea; together they are a sibling couple that conforms to a familiar pattern of differential radiation and vicariant dispersal within and to the southeast of the Amazonian Hylaea. The relatively ample stipules, long-clawed petals and large median anthers reliably distinguish C. fastuosa at anthesis or in young leaf, and later on the narrower, less prominently 4-costate pod, in which the more numerous seeds are packed into locules only half as long, is distinctive. Although the flower of C. fastuosa is prevailing larger than that of C. ferruginea, there is some overlap in overall length of petals, especially in the more northern populations of the latter (var. ferruginea) and those disjunct in the wet coastal forest of southern Bahia, exactly where one might expect to find evidence of a common origin. Until lately C. fastuosa has appeared to differ from C. ferruginea in the velvety-puberulent, not early glabrate pod, but this difference fails in C. fastuosa var. calva described below.

    Our material of C. fastuosa from French Guiana and lower Amazonia in Para and Amapa appears identical at anthesis with that obtained in the Madeira-Purus basins in the southwestern Hylaea. In both the ovary is pilosulous, but its subsequent history is different in the two regions. In lower Amazonia the expanding epidermis of the fertilized ovary acquires, in addition to its original vesture, a plushlike indumentum of minute silvery gray or at first yellowish hairs which persists into full maturity of the fruit. In Acre, Rondonia and adjoining Mato Grosso and Beni no secondary indumentum develops and the pilosulous hairs of the ovary are quickly dispersed over the expanding valves and ultimately lost altogether, the half-grown pod becoming smooth and lustrous. Except for one collection from Humayta on the Madeira (Krukoff 6989, NY), of which the mature pod appears to have been velvety when young, the two forms are widely and effectively separated in dispersal and consequently deserve taxonomic status.

    Several collectors have recorded the strong agreeable perfume of the flowers of C. fastuosa, likened by George Black to the aroma of passionfruit.

    Key to Varieties of C. fastuosa

    1. Fertilized ovary acquiring a dense plushlike indumentum of minute whitish or yellowish hairs, this persisting throughout the life of the developing fruit, the fully formed pod velvety- puberulent; French Guiana, n.-e. Brazil (Amapa, Para), rarely w. to Manaus and the middle Maderia R. in Amazonas). 11a. var. fastuosa (p. 42).

    1. Fertilized ovary lacking a secondary indumentum, its pilosity quickly dispersed over the expanding valves of the pod and ultimately deciduous, the developing and mature pod glabrate lustrous; s.-w. Brazil (Acre, Rondonia, n. Mato Grosso) and adjoining Bolivia (Beni). 11b. var. calva (p. 43).