(CAESALPINIACEAE)--A NEW SPECIES FROM SOUTH INDIA

Transcription

1 CASSIA INTERMEDIA (CAESALPINIACEAE)--A NEW SPECIES FROM SOUTH INDIA B. D. SHARMA, K. VIVEKANANTHAN* AND N. C. RATFIAKRI$IilqAN (Botanical Survey of India, Central Circle, Allahabad 2) MS received 1 March 1974 ABSTRACT A new species, Cassia intermedia Sharma, Vivek. & Rathak. is described and illustrated. The natural interspecific hybridisation between C. occidentalis Linn. and C. hirsuta Linn. has resulted in the evolution of the new species. This finding has been corroborated by external morphological features and the phytochemical analysis. Cassia intermedia Sharma, Vivek. et Rathak., spec. nov. Differt a C. occidentali Linn. pilis hirsutis super ramos juniores, foliola (utraque superficie) et legumina: affinis etiam C. hirsutae Linn. sed differt praecipue leguminibus compressis, minus pilosis et vix torulosis. Frutices erecti, m alti; caules lignosi, teretes, saepe suleati; rami maturiores puberuli, juniores vero hirsuti et valde flexuosi. Folia bipinnata; rhachis cm longa, puberula, glande solitaria, sessilia, globosa vel ovoidea, 4-2 mm supra basim ; stipulae 5-6 mm longae, hirsutae ; foliola (3-) 4-5 (-6), unumquidque cm, paribus acerescentibus, subcoriacea, utraque superficie hirsuta, ovata ad ovato-oblonga, apice acuta vel acuminata, basi vero anguste vel late rotundata et aliquando inaequilateralia, integra; petiohdi 1-2 mm longi, hirsuti. F!ores racemis brevipedunculatis et paucifloribus in paniculis axillaribus vel pseudoterminalibus dispositis; bracteae 4-5mm longae, lanceolatae, hirsutae; pedieelli 0.8-1"2cm longi, usque ad 2"5 cm crescentes in fructu, puberuli. Sepala cm, subaequalia, late ovata, concava. Petala t" cm, subaequalia, lutea, venis prominentibus, obovato-suborbiculatus. Stamina 10; infima 2 longissima, filamentis 4-8 mm longis, glabris, curvatis; antheris 4-6 mm longis, apice latis, poro apicali aperientibus; 4 lateralia filamentis 4-3 mm longis, antheris vero 4-4 mm longis; suprema * Botanical Survey of India, Southern Circle, Coimbatore 2. B5gDoe

2 302 B.D. SHARMA AND OTHERS 3 et infima i ad staminodia deminuta. Ovarhtm em longum, pubescens ; stylus 4-3 mm longus, glaber. Legumina cm, compressa, Iinearia, saepe leviter curvata, vix torulosa, hirsuta, suturis non distinctis; semhza 4-4 x 4 mm, fusca, ovato-suborbiculatus (Figs. 1-12). Holotypus, Sharma A et isotypi, Sharma B-D lecti ad Thekkady, dist. Idikki in statu Kerala, die Paratypi, Vivekananthan A-E lecti eodem in loco, die , Vivekananthan A-C lecti eodem in loco, die , Sharma A and B lecti ad Moyar, dist. Nilgiris in statu Tamil Nadu, die et Fivekananthan A-E lecti ad Theppakadu, dist. Nilgiris in statu Tamil Nadu, die Holotypus positus in herbario centro nationalis, Calcutta (CAL), isotypi et paratypi positi in herbario regionis australis, Coimbatore (MH). Cassia intermedia Sharma, Vivek. & Rathak., spec. nov. It differs from Cassia occidentalis Linn. by the presence of hirsute hairs on the younger branches, leaflets (both surfaces) and fruits. Also allied to C. hirsuta Linn. but differs mainly in having pods compressed, less hairy and scarcely torulose. Erect shrubs, m tall; stems woody, terete, often furrowed; older branches puberulus, younger hirsute and zigzag. Leaves bipinnate; rhachis cm long, puberulus with a solitary, sessile, globose or ovoid gland 4-2 mm above the base; stipules.5-6 mm long, lanceolate, hirsute; leaflets 3-6, each x cm, in aecreseent pairs, subcoriaceous, hirsute on both surfaces, ovate to ovate-oblong, acute or acuminate at apex, narrowly or broadly rounded and sometimes inequilateral at base, entire; petiolules 1-2 mm long, hirsute. Flowers in short-peduncled, fewflowered racemes arranged in axillary or pseudoterminal panicles; bracts :k 5 mm long, lanceolate, hirsute; pedicels em long elongating up to 2"5 cm in fruit, puberulus. Sepals subequal, x 0"5-0.7cm, broadly ovate, concave. Petals subequal, 1-5 x cm, yellow with prominent veins, obovate-suborbicular. Stamens 10; 2 lower longest, with ±. 8 mm long, glabrous, curved filaments and :i: 6 mm long anthers with broadened top opening by an apical pore; 4 laterals with + 3 mm long filaments and :i: 4 mm long anthers ; upper 3 and lower 1 reduced to staminodes. Ovary i 1-2cm long, pubescent; style± 3 mm long, glabrous. Pods x cm, compressed, linear, often slightly curved, scarcely torulose, hirsute, sutures not distinct; seeds i 4 x 4 ram, brown, fiat, ovate-suborbicular (Figs. 1-12).

3 Cassia intermedia (Caesalpiniaceae) 303 I0 o 9 II f, Figures Cas~+ia intermedia Sharma, Vivek. & Rathak. Fig. I. Flowering t~ig, FiBs.2 and 3. Sepals, Figs Petals, Fig. 7. Staminode, Fig. 8 and Fig. 9. Stamens, Fig. 10. Ovary, Fig. 11. Pod. Fig. 12. Seed.

4 304 B.D. SHARMA AND OTHERS Holotype, Sharma A collected on 12 March 1973 from Thekkady, Idikki District, Kerala, is deposited in the Central National Herbarium, Sibpore, Calcutta (CAL) and isotypes, Sharma B-D and paratypes, Vivekananthan A-E (Thekkady, Idikki District, 28 January 1965), Vivekananthan A-C (Thekkady, Idikki District, 26 November 1967), Sharma A and B (Moyar, Nilgiri District, Tamil Nadu, 18 August 1970) and Vivekananthan A-E (Theppakadu, Nilgiri District, Tamil Nadu, 9 April 1972) are housed in the Herbarium of the Southern Circle, Botanical Survey of India, Coimbatore (MH). The new species Cassia intermedia Sharma, Vivek. & Rathak., presented here, has been collected from two different localities, viz., Thekkady, Kerala State and Mudumalai, Tamil Nadu. Though one or the other author could collect this interesting species as early as in 1965 and subsequently in 1967, 1970, 1972 and 1973, the taxonomic delimitation of this taxon with the closely allied species, C. occidentalis Linn. and C. hirsuta Linn. could not be ascertained till the phytochemical analysis of the leaf samples of all the three species under discussion was carried out at the University of Reading, UK and correlated with the field observations made by the authors. The hybridisation between species, which is one of the principal means of speciation, is not uncommon in nature. However, the percentage of those successfully evolved, established and naturalised hybrids is very small as compared to the total number of individuals in the hybrid population. The rarity of such phenomenon taking place in nature is not due to the difficulty of producing interspecific hybrids, but to the meagre chance of those hybrids becoming established. Both the species of Cassia, viz., C. occidentalis Linn. and C. hirsuta Linn. were found growing along with C. intermedia sympatrically at both the localities which are approximately 300 km apart. The occurrence of C. occidentalis and C. hirsuta is a common feature in waste lands. However, their occurrence sympatrically in a new ecological niche or environmental condition--marshy substratum--might have provided suitable habitat for the establishment of the new entity. Besides the external morphological characters, the phytochemical findings corroborate its hybrid origin. The chromatographic pattern of Cassia hirsuta and C. occidentalis have~differentprotiles (Figs. 13and 14). The new species Cassia intermedia Sharma, Vivek. & Rathak. (Fig. 15) shows the additive inheritance of the chemical characters. The chromatograph of mixed extracts of the two

5 Cassia irttermedia (Caesalpiniaceae) :305,; w ii z - ~ il ~ L ili: ~[- o~ ~I ~--~ I % g T o Q -, oo c:~ m

6 306 B. D. SHARMA AND OTHERS parental species (Fig. 16) closely match with that of the Cassia intermedia Sharma, Vivek. & Rathak. The robust habit of the new species and its occurrence in the new niche gives an impression of polyploidy. The additive inheritance of the phytochemicals further substantiate this hypothesis. However, a chromosomal count of the new species would deafly solve this riddle. ACKNOWLEDGEMENTS The authors express their deep sense of gratitude to Dr. J. B. Harborne, Department of Botany, Plant Science Laboratory, University of Reading (U.K.), for providing phytochemical data. They are also indebted to Dr., 1~. ML Matthew, St. Joseph's College, Tiruchirapalli (Tamil Nadu)., for rendering Latin translation.