Cassia javanica

  • Title

    Cassia javanica

  • Author(s)

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Cassia javanica L.

  • Description

    13.  Cassia javanica Linnaeus, Sp. Pl. 379, 1753.—Typus infra sub var. javanica indicatur.

    Semideciduous trees of rapid growth, attaining 25, rarely 40 m, some flowering precociously, where not crowded amply round-crowned with downs wept branches, these and the trunk either smooth or armed with persistent spiniform branchlets, the young parts varying from minutely puberulous to densely pilosulous, the phyllotaxy distichous, the simply or paniculately racemose inflorescence terminal to lateral branchlets, these either leafless from annotinous or even older branchlets or basally leafy from hornotinous growth.

    Stipules 2-lobed, highly variable in development, either thinly foliaceous and reniform or crescentic, laterally attached, each lobe obtuse mucronulate or apiculate-acuminulate, the blade attaining 25 x 1 cm measured between tips of lobes, or both lobes subulate-linear and less than 1 mm wide, the lower lobe then often divaricate-ascending, in any case early caducous and absent from mature specimens.

    Lvs heteromorphic, progressively longer and more complex upward along each annual increment of stem, those of flowering branchlets always relatively short and simple, the longest lvs attaining ±2-3.5(-4.3) dm, the shortest rarely less than 1 dm; lfts (4-)8-17(-20) pairs, subequilong or the lowest and sometimes the terminal pairs a little smaller than the rest, all quite variable in outline, either ovate-obtuse, or ovate-acuminulate, or broadly oblong obtuse or deltately acute, or obovate obtuse or emarginate, the longer ones (3-)3.5-8(-9) x 1.5-3.2 cm, when adult sublustrous and intricately reticulate.

    Racemes subsessile, densely 10-many-fld, subcorymbose at anthesis, the several simultaneously expanded fls raised to level of nodding buds, the axis becoming 3- 12(-18) cm; bracts thinly herbaceous, persistent with the similar but shorter bracteoles into anthesis, broadly to narrowly ovate-acuminate from broadly cuneate or subcordate, rarely auriculate base, less often lance-attenuate, 5- 12(- 17) mm long; pedicels widely ascending, including the hypanthium (2.5-)3-6 cm; hypanthium slenderly vase-shaped 2.5-6 mm; sepals firm, green or purplish, subequilong, ovate, oblong-obovate or lanceolate obtuse or rarely subacute, the longest 4-10 mm, all reflexed at anthesis and puberulent on both faces; petals widely spreading subhomomorphic, pale pink or carmine at full anthesis fading whitish, buff-pink or (dry) orange-buff, puberulent dorsally, including the short claw (15-) 18-35 mm long, in outline varying from broadly obovate to oblong-elliptic or oblanceolate and at apex from broadly rounded to subacute, 8-16 mm wide; androecium yellow, like that of C. fistula except for long filaments abruptly or gradually dilated in their distal curve into a plump ellipsoid or subglobose nodule 3.5-5 x (1.1-) 1.7-2.5 mm, the anthers thinly puberulent dorsally, those of 3 long stamens 2.4-4.3 mm, of 4 fertile antesepalous ones 3-5.5 mm; ovary strigulose, pilosulous or glabrescent; ovules 68-94.

    Pod pendulous short-stipitate, the body elongately pipelike terete or a trifle obcompressed 4-6 dm x 1.4-1.8(-2) cm, straight or almost so, the sutures neither thickened nor prominent, the valves atropurpureous, dark brown or almost black and glabrate at maturity, obscurely constricted at the septa, the firm endocarp only 0.2-0.3 mm thick in section, the interseminal septa almost papery 0.1-0.2 mm thick, each locule filled with a finally detached suberous disc 4-5 mm thick enveloping a seed; seeds horizontal, broadside to the septa within their suberous envelope, plumply biconvex-obovid, ±6.5-8 x 6-7 x 4-5.5 mm, the hilum sub- basal on one broad face, the testa pale or chestnut brown, smooth and glossy; x = 12, 14.—Fig. 2 (pod).

    As described herein, C. javanica consists of a complex series of forms thought to be native from the Bay of Bengal southeast through Malaya, Sumatra and Indonesia to Timor and New Guinea and through Indochina to southern China (Yunnan) and the Philippines, but for so long and so widely planted for ornament both within and beyond its supposed homeland that aboriginal patterns of dispersal are now difficult or impossible to reconstruct. The plants vary between themselves in a) pubescence b) amplitude of stipules, c) shape of leaflets, d) position of racemes on new or old wood, accompanied or not by coeval foliage, e) size of calyx, f) amplitude and length (not necessarily correlated) of petals, g) size of fertile anthers, and h) chromosome number; furthermore some trees are said to have, particularly when immature, trunks and annotinous branchlets armed with persistent spinescent branchlets, but the significance of this feature, seldom noted by collectors and not seen on herbarium specimens, cannot be estimated. In the past, various syndromes of the characters just listed have been evoked in support of segregate species C. nodosa Buch.-Ham. ex Roxb., C. megalantha Dcne., C. agnes (De Wit) Brenan, and the varieties indochinensis Gagnep. and pubifolia Merr., but the identification of specimens is still difficult and the literature is contradictory. The species most persistently segregated from C. javanica, latterly with explicit misgivings, is C. nodosa, originally described from trees grown by Roxburgh at the Calcutta Botanic Garden, to which it was introduced from the region of the Ganges Delta (Chittagong, East Pakistan). Recent and contemporary authors who maintain C. nodosa either as a distinct species or as a subspecies of C. javanica (De Wit, 1955, p. 204; Isely, 1975, p. 101; Ali, 1973, p. 10; K. & S. Larsen, 1974, p. 205) attribute to it relatively small (but still dilated) stipules, short petals and acute leaflets; but this formula cannot be applied usefully to the whole complex, for stipules proper in C. nodosa may be found on plants with obtuse-retuse leaflets or large flowers (or both). When Brenan (1958, l.c.) raised C. javanica var. agnes De Wit to specific rank he introduced as a taxonomically meaningful criterion a difference between leafless cauliflorous simple racemes and leafy terminal, simple or branched ones, the branched type being supposedly characteristic of C. agnes. This same mode of variation was noticed in Philippine C. javanica by Merrill (Philip. J. Sci., Bot. 6: 48. 1910) who, somewhat paradoxically but perhaps following King (Mat. Fl. Malay Pen. 9: 155. 1902), associated cauliflory with C. nodosa, not with C. javanica as most others have done. Backer & Backhuizen van den Brink (Fl. Java 1: 537. 1963) state that in Java C. javanica and C. nodosa both flower from defoliate branches, but they maintain the species as different in the intensity of sepal and flower color, in average shape of leaflets and in size of calyx (nodosa 5-7.5 mm, javanica 7.5-10 mm). No consensus as to the differential characters, the taxonomic status, or the exact dispersal of C. nodosa has been reached.

    In our search for acceptable names for the cassias of the C. javanica complex cultivated and weakly naturalized in the Americas, we have sorted all available Asiatic material in several ways, using each of the variable features listed in the preceding paragraph as the primary division. Partition by characters a, c, d and f produced assortments which were either flagrantly improbable from the geographic viewpoint or were internally heterogeneous in parallel ways, or both at once. A dense pilosulous vesture of foliage and inflorescence was encountered only in the Philippines, but was found associated there either with broad foliaceous or minute subulate stipules and with inflorescences arising either from new or from old branches; moreover a pilosulous inflorescence combined with merely puberulent foliage occurs at random points in the range of the complex. We regard such pubescence variants as beneath taxonomic notice, although they can be visually striking and may have horticultural value. Merrill and De Wit (11. cc.) have noticed the variation in leaflet outline and we think rightly regard this as superficial, for it is not consistently linked with any other single character-state or combination of such. Position of the inflorescence in relation to annotinous foliage would be significant if it could be shown that two fundamentally different types of raceme were present, as suggested by Brenan’s emphasis on a branched panicle terminating leafy branchlets supposed to characterize C. agnes. In reality all inflorescences of C. javanica sens, lat., whether simple or branched, terminate branchlets lateral to a primary indeterminate (seldom collected) leafy axis; they are generally leafless when arising from older wood and vary from leafless to several-leaved when arising from annotinous growth, a phenomenon that occurs also in Brazilian C. ferruginea. Transition from leafless cauline and leafy subterminal racemes (branched or not) is not be denied, and once again we agree with De Wit and Merrill in devaluating the taxonomic import of this character. It is noteworthy in this connection that Roxburgh’s portrait of the original C. nodosa cultivated at Calcutta that was published in Wight’s leones (l.c.) shows a leafy branchlet bearing one major and one lateral minor raceme, an arrangement not fundamentally different from the inflorescence attributed to C. agnes. The two chromosome numbers reported in C. javanica sens. lat. suggest genetically distinct species, and this line of investigation should be followed up by Asiatic botanists who have ready access to fresh material of morphologically different populations. The senior author’s count (Irwin & Turner, 1960, p. 310) of 2x = 28 relates to var. indochinensis of this revision; that of x= 12 lacks a voucher and cannot be tied in with any particular form of the species.

    Characters that we have found promising for the purposes of classification are development of the stipules, the size (but not the color) of the sepals, and the size of the fertile anthers, for these in varying combinations, sometimes reinforced by petal-length, appear to be related to the dispersal of plants certainly or probably wild. The fleeting nature of stipules, which are never found associated with mature leaves or with pods, is a practical handicap, and we have found the identification to variety of fruiting C. javanica possible only by inferential matching with more or less sympatric flowering specimens similar in foliage. In spite of difficulties and uncertainties which are unavoidable in our present state of ignorance we can dimly recognize four main classes of specimens which may provisionally be referred to four varieties of C. javanica. The recognition of more than one independent species in the complex is no longer possible.

    Key to Varieties of C. javanica

    1. Stipules dilated, amply foliaceous reniform or moderately dilated crescentic, the lobes diametrically opposed and the blade at point of attachment (1.5-)2-10 mm wide. Anthers of 4 fertile antepetalous stamens 4-5.5 mm; petals (23-)25-42 mm.

    2. Blade of stipules amply foliaceous venulose, at least 1 cm long from tip to tip of lobes and at least 1/3 as wide; sepals (6.5-)7-10 mm; native in Indonesia e.-ward from Java, n. to Luzon in Philippine Is.

    13a. var. javanica (p. 50).

    2. Blade of stipules crescentic up to 18 mm long but not over 5 mm wide; sepals 5.5 7 mm, n.-e. India through Indochina to s. China, widely diffused in cultivation.

    13b. var. indochinensis (p. 50).1. Stipules not dilated, the lobes subulate-linear less than 1 mm wide, the lobes often divergent at ±90°.

    3. Calyx relatively large, the sepals 6-9 mm; anthers of 3 long stamens 3.5-4.3 mm, o fertile antepetalous ones 4-5.5 mm; petals 20-32 mm (note: in spite of epithet on y sometimes densely pubescent).

    13c. var. pubifolia (p. ).3. Sepals 4-4.5 mm; anthers of 3 long stamens 2.2-2.9 mm, of 4 fertile antepetalous ones 3—4 mm; petals mostly 15-20, rarely -25 mm.

    13d. var. microcalyx (p. 51).