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Home , Cordyline, Cordyline indivisa, Dracaena (plant)

_??_1989 by Cytologia, Tokyo Cytologia 54: 573-579, 1989

Cytology of of and from South India

P. M. Mathew and B. Vijayavalli

Department of Botany, University of Kerala, Kariavattom, Trivandrum-695 581, India

Accepted September 21, 1988

Cordyline Commers and Dracaena Linn. are two closely related genera belonging to the tribe Dracaeneae of Hutchinson's (1959) Agavaeae. Cordyline is a small , chiefly dis tributed in the Malayan, Australasian and Pacific regions. Hooker (1984) has described only one species in the peninsular India, but a few others are known here under cultivation for ornamental purpose. Dracaena is a woody tropical genus whose members are known for their graceful attractive foliage. Airy Shaw (1973) has recognised 150 species, distributed allover the globe. Hooker has reported 15 species in India, and in addition a large number of exotic species also occur here, grown for ornamental purpose. Cytology of three species of Cordyline and 12 taxa (10 species) of Dracaena is reported here.

Materials and methods

Materials of the species were procured from different gardens in South India. Chromo some studies were made from PMCs at meiosis and/or root tips. Flower buds and root tips

were fixed in 3:1 Carnoy's fluid. Root tips were pretreated in 0.002M solution of 8-hydroxy

- quinolin for 2 hrs at 4•Ž. Simple acetocarmine smear and squash technique was followed for making chromosome preparations.

Observations

Cordyline indivisa Hook, f. Root tip cells showed 38 small sized chromosomes (Fig. 3). The same chromosome num ber was previoulsy reported for the species (Rattenburry 1957). C. stricta Hook. f. Root tip cells showed 38 chromosomes which ranged in size from 2.4-0.67ƒÊm (Fig. 4). The chromosomes had median and submedian centromeres. Previously Singh (1978) reported two cytotypes, a diploid with 2n=38 and a polyploid with 2n=114. The polyploid cytotype had also been reported much earlier by Sato (1942) in the Japanese material. C. terminalis Kunth. Pollen mother cells showed 19 bivalents at meiosis (Fig. 1). Root tip cells showed 38

small sized chromosomes ranging from 2.0 to 0.6ƒÊm (Fig. 2). The same chromosome num ber was reported previously (Rattenburry 1957, Sharma and Gosh 1968). Ker-Gawl. This is a -like species with broad, laxly recurved, oblancealate, soft and leathery leaves forming a continually ascending and shining green rosettee, and producing fragrant yellowish flowers in clusters. Nineteen bivalents were observed in PMCs at diakinesis (Fig. 5). Root tip cells showed

38 small sized chromosomes ranging from 3.00 to 1.20ƒÊm in length (Fig. 6). Most of the chromosomes possessed nearly median or sub-median centromeres. The same chromosome number was reported previously by Sharma and Ghosh (1968), and 2n=42 by Singh 1978. 574 P. M. Mathew and B. Vijayavalli Cytologia 54

Figs. 1-12. Meiotic and mitotic chromosomes of species of Cordyline and Dracaena. •~1300.

1, Cordyline terminalis, diakinesis, n=19, 2, C. terminalis, 2n=38. 3, C. indivisa, 2n= 38 . 4, C. stricta, 2n=38. 5, Dracaena fragrans, diakinesis, n=19. 6, D. fragrans, 2n=38. 7, D.

fragrans var. 'victoria', diakinesis, n=19. 8, D. fragrans, var. lindenii, diakinesis, n=19. 9, D.

godseffiana, metaphase I, n=18. 10. D. godseffiana, 2n=36. 11, D. dremensis, diakinesis, n=19. 12, D. dremensis, 2n=38. 1989 Cytology of Species of Cordyline and Dracaena 575

D. fragrans var. 'victoria' This variety is characterised by leaves with the middle region green and with broad golden yellow margins. This also showed 19 bivalents in PMCs (Fig. 7). D. fragrans var. 'Lindenii' This has wide limpy pendant leaves with broad , often indistinct greenish yellow bands at margins, and with the centre green . This variety showed 19 bivalents in PMCs (Fig. 8) and 38 chromosomes in root tip cells . D. godseffiana Hort. This is a small shrubby , popularly known as 'florida beauty' The possessed spreading curly stems and thin leathery elliptic leaves in whorls of three . Leaf blade is glossy, deep green and irregularly spotted yellow . Eighteen bivalents were observed in PMCs (Fig. 9) and 36 small sized chromosomes in root tip cells (Fig . 10). Previously a polyploid cyto type with 2n=84 was reported (Sharma and Datta 1960). D. dermensis 'Warneckee' This species has sessile sword-shaped, leathery and green-streaked leaves which are milky green in centre and bordered with a transluscent white band on each side inside the narrow bright green edge. PMCs showed 19 bivalents (Fig. 11) and root tip cells showed 38 small sized chromosomes (2.5 to 1.0ƒÊm) with nearly median centromeres (Fig . 12). Previously Singh (1978) has reported 2n=40, 42 and 84 in this species. Sato (1942) had reported 2n= 38 in the Japanese material. D. kindtiana Hort. The plants are relatively shorter with green leaves. Petioles are erect and long, sometimes as long or even longer than the lamina which are borne at right angles to the petiole. The leaves are sagittate in shape and with a rigid surface. This species also showed 19 bivalents during meiosis (Fig. 13) and 38 small sized chromosomes in root tip cells (Fig. 14) with nearly median centromeres. Previously Singh (1978) has reported 2n=40. D. marginata Hort. This species has branching slender trunks, with a terminal rosette of green, narrow rib bon-shaped leaves with tapering ends and narrow red margins. During meiosis, diakinesis showed 19 bivalents (Fig. 15). Previous workers have reported 2n=40 (Sharma and Ghosh 1968) and 2n=42 (Singh 1978). D. reflexa Lamt. This is a tropical evergreen species with slender flexuous stem eventually becoming scan dant, densely furnished with clasping narrow and leathery leaves beautifully margined by two wide bands of golden yellow. This species showed 19 bivalents at diakinesis in PMCs (Fig. 16) and 38 small sized chromosomes in root tip cells with nearly median and sub-median cen tromeres. Previous workers have reported different somatic numbers such as 2n=40 (Sharma and Ghosh 1968) and 42 (Singh 1978). D. sanderiana Hort. This plant, popularly known as 'Ribbon plant', has beautiful lanceolate leaves with green central band and broad yellowish white margins. This species also showed 19 bivalents at diakinesis (Fig. 17) and 38 small sized chromosomes (2.00-1.00ƒÊm) in root tip cells (Fig. 18). The present count is at variance with the earlier report of 2n=32 by Sharma and Datta (1960),

2n=40 by Gradella (1977) and 2n=42 by Singh (1978).

D. spicata Roxb. This is a shrubby species with green leaves showing great variation in size. Materials of this consistently showed 19 bivalents in PMCs (Fig. 19). Meiosis was fairly normal with re gular anaphase separation (Fig. 20). Root tip cells showed 38 chromosomes (Fig. 21). The karyotype appeared to be fairly symmetrical as bulk of the chromosomes had their centromeres 576 P. M. Mathew and B. Vijayavalli Cytologia 54

Figs. 13-24. Meiotic and mitotic chromosomes of species of Dracaena. •~1300. 13, Dracaena kindtiana, diakinesis, n=10. 14. D. kindtiana, 2n=38. 15, D. marginata, diakinesis, n=10. 16,

D. reflexa, diakinesis, n=19. 17. D. sanderiana, diakinesis, n=19. 18. D. sanderiana, 2n=38. 19, D. spicata, diakinesis, n=19. 20. D. spicata, anaphase 1. 21, D. spicata, 2n=38. 22, D.

surculosa, diakinesis, n=20. 23. D. ternifolia, metaphase I, n=19. 24, D. ternifolia, 2n=38. 1989 Cytology of Species of Cordyline and Dracaena 577

located in the median or submedian region . The somatic chromsomes were small sized (3.00

-1.40ƒÊm) without appreciable size difference of chromosomes . Previously Singh (1978) has reported 2n=40.

D. surculosa Hort. This is a branching plant with whip-like wiry stems, distantly bearing pairs or whorls of long elliptic, olive-green and leathery leaves with indistinct pale white patches. During meio sis 20 bivalents were observed at diakinesis (Fig. 22). D. terniflora Roxb. This is a low decumbent slender with elliptic oblanceolate and fairly acuminate leaves. This showed 19 bivalents during meiosis and 38 chromsomes in root tip cells (Figs. 23, 24). The somatic chromosomes were small sized with no appreciable size variation and with nearly median and sub-median centromeres. A polyploid cytotype (2n=80) has been previously reported (Sheriff and Singh 1973, Singh 1978).

Discussion All the species of Cordyline reported here are based on x=19. One of the species (C. stricta) exists as a polyploid cytotype (2n=114) elsewhere in India (Singh 1978). Of the 12 taxa (10 species) of Dracaena reported here, one each has n=18 (D. godseffiana) and n=20 (D. surculosa), and all the rest have n=19. In some of the n=19 and 2n=38 species, diploid cytotypes with 2n=40 and 42 and polyploids with 2n=80 and 84 also have been reported earlier (Gradella 1977, Sharma and Ghosh 1968, Sing 1978). The chromosome data so far known show that the genus has four basic numbers (x=18, 19, 20, 21), of which x=20 could be the earlier evolved one. The solitary instance of a taxon with n=10 (D. baptistii) reported by Sharma and Datta (1960) appears to indicate that x=10 could be the primary basic consti tution in Dracaena from which x=20 condition arose by polyploidy which in turn given rise to x=19, 18 and 21 by aneuploidy in either direction. Further evolution, as it appears, must have been through polyploidy resulting in taxa with 2n=80, 84, 114 etc. The chromosome situation in Dracaena thus indicates that both polyploidy and aneuploidy have played signifi cant role in the evolutionary history of the genus. The diploid cytotype of D. terniflore (2n=40) reported here from South India appears to be interesting. Previously Sheriff and Singh (1973) had reported a 2n=80 tetraploid cytotype from here. On the basis of exomorphic, cytological and cytogeographical data on D. tern (flora and D. spicata, they have suggested that the tetraploid D. terniflora might have arisen as an al lotetraploid derivative in the North-Eastern region of the Indian subcontinent through hybridi sation between D. spicata (2n=40) and some other diploid species with 2n=40, and subsequent ly migrated to Malaysia and also down to South India. Now with the detection of the diploid cytotype of D. terniflora from South India, it becomes apparent that the tetraploid taxon re ported by Sheriff and Singh might have originated in this region itself. The other diploid taxon which they have speculated to be one of the parents of their tetraploid D. tern flora must be the above diploid cytotype of the species. Hutchinson (1959) has removed Bentham and Hooker's Liliaceous genera such as Draca ena, and Cordyline, and Amaryllidaceous genera Agave, Doryanthus etc. from their re spective families and treated them under a newly created , Agavaceae under the order Agavales. Most of the modern taxonomists agree that Hutchinson's treatment, although based on evidences from external morphology alone appear as an attempt in the right direction notwithstanding certain pitfalls in minor details. In Hutchinson's classification, the tribe Dracaeneae includes four genera such as Cordyline, Dracaena, and Cohnia. In exomorphology and chromosome make-up, species of Dracaena and Cordyline are very similar. 578 P. M. Mathew and B. Vijayavalli Cytologia 54

Both the genera have similar basic chromosome series (x=18, 19, 20) and small sized chromo somes with graded and fairly symmetrical karyotypes. The other two genera, although dif ferent in exomorphology, also have comparable chromosome situation which indicate that a high degree of karyological homogeneity exists within this tribe. The other tribes of Hutch inson's Agavaceae (Yucceae, Agaveae, Polyantheae) exhibit a chromosome condition distinct from that of the Dracaeneae (x=30 and extreme intrakaryotypic size difference), and hence on karyological consideration, there appears to be very little relationship between Dracaeneae and the other tribes of Hutchinson's Agavaceae, which apparently poses need for removal of the tribe Dracaeneae from the Agavaceae. Sharma and Choudhury (1964) have pointed out that, as the chromosomes of Dracaena resembled those of Ophiopogon (Liliaceae) and as the relationship between the two has been accepted by most taxonomists, they can better be accommodated in the same assemblage in a separate tribe under the Liliaceae or in a distinct family separated from the Agavaceae. In the recent classification by Takhtajan (1980) the members of the Dracaeneae are treated in a separate family, Drecaenaceae which according to him is related to and Ophi opogon, and probably have a common origin. He has kept them all under his Liliales. Da hlgren and Clifford (1982) and Dahlgren et al. (1985) who have also treated this as a separate family closely related to their Asparagaceae, have however, kept it under their . On exomorphic (woody) as well as on chromosomal similarity (x=10 and small sized chromo somes) the suggested relationship between Asparagus and Dracaena appears to be sensible.

Summary

Cytology of three species of Cordyline and ten of Dracaena is reported from South India. The gametic numbers observed in species of Cordyline is n=19 and in Dracaena are n=18, 19 and 20, of which n=19 predominated. Chromosome data show that both the genera have similar basic chromosome consitution (x=18, 19, 20) and small sized chromosomes. The x=20 in Dracaena is postulated to be the earlier evolved one by polyploidy from a possible x=10 primary condition. Polyploidy and aneuploidy appear to have played significant role in speciation and evolu tion in the genus. Systematic relationships of the genera is considered. Hutchinson's treatment of Cordy line and Dracaena along with Sansevieria and Cohnia in the same tribe (Dracaeneae) is pointed out to be justifiable on karyological grounds. But this tribe appears to have very little cytol ogical likeness with the other tribes of Hutchinson's Agavaceae, and this supports the suggested removal of Dracaeneae from the Agavaceae.

Acknowledgements

The authors are grateful to Prof. C. A. Ninan, Head of the Department for encouragement and facilities. One of us (BV) is thankful to the University Grants Commission, Government of Kerala and to the Management of the S. N. Trust for financial assistance and study leave benefits during the course of this work.

References

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