1970 13 A Cytological Study of the Zingiberales with Special Reference to Their Taxonomy1 H. K. Mahanty Sir John Cass College, London E. C. 3., Great Britain2 Received September 16, 1968 Abstract The chromosome numbers have been determined for sixty four species spread over all the families of Scitamineae. In about eighteen of these species, meiosis has been studied. The findings are correlated with the presumed evolution of the various groups. The evolution of the chromosome complements in the various families is discussed in the light of the past and present findings. In Musaceae (broad sense) three distinct groups: (a) Musa-Ensete, (b) Heliconia and (c) Ravenala-Strelitzia-Phenakospermum are recognised and sub-familial status proposed for these. According to the cytological data it is concluded that the genus Zingiber should be included in the tribe Hedychieae. From the evidence of flower morphology, geographical distribution and cytologi cal differences it is proposed that the African representative of Kaempferia should be restored to the status of a separate genus, Cienkowskya of Solms Laubach. It is suggested that haploid number 11 is the original basic number for the whole of the Scitamineae, and other numbers such as, 9, 10, 11, 12, 13, 14, 16 and 17 are secondary in origin. Of these, 9 occurs exclusively or predominantly in Ensete. Costus, Canna, and Orchidantha, 12 in the sub-family Zingiberoideae and 13 in Marantaceae. The names of the species which have been studied in the present investigation are given below:- MUSACEAE 1. Ensete sp., 2. Musa sp., 3. M. sapienoum Linn., 4. M. cavendishii lamb, 5. Heliconia caribea Lam., 6. H. bihai Lin., 7. H. brasiliensis Hook., 8. H. aurantiaca, Ghiesbreght., 9. Strelitzia reginae. Banks., 10. S. parvifolia. Dryand 11. S. parvifolia var juncea Bot. Reg. LO WIACEAE 2. Orchidantha longiflora H. Winkl., 13. O. maxillaroides (Ridl.) K. Schum. ZINGIBERACEAE 14. Tapeinochilus ananassae Hasak., 15. Costus macrostrobilus K. Schum., 16. C. albus A, Cheval., 17. C. niveus G. F. W. Mey., 18. C. sp. (Nigeria); 19. C. sp. (Costa Rica), 20. C. schlechteri H. Winkler., 21. C. englerianus K. Schum, 22. Hedychium thyrsiforme, Ham., 23. Kaempferia angustifolia Roscoe., 24. K. elegans Wall., 25. K. pulchra Ridl., 26. K. gilbertii. Hort., 27. K. rotunda. Linn., 28. K. carsonii. Bak., 29. K. sp. (African); 30. K. kirkii (Hook) Witt et per, 31. 1 This paper is compiled from two theses submitted for M. Sc. and Ph. D. of London University. 2 Present address: Cawthron Institute, Nelson, New Zealand. 14 H. K. Mahanty Cytologia 35 K. aethiopica (solms) Benth., 32. K. rosea. Schweinf; 33. K. sp. (African); 34. K. brachystemon K. Schum., 35. "K. ethleae". 36. Zingiber spectabile Griff., 37. Z. cylindricum Moon. 38. Globba winitii Wright., 39. G. heterobractea K. Schum., 40. G. albiflora var. aurea (Ridl) Holtt., 41. Alpinia mutica Roxb., 42. A. formosama K. Schum., 43. Roscoeae purpurea Smith., 44. R. alpina Royle; 45. R. cautleoides Gagnep., 46. R. Lumeaua Balf. et Sm., N. R. sp. MARANTACEAE 54. Calathea albertii fide Roy. Bot. Gdn. Edin., 55. C. cylinerica (Roscoe) K. Schum., 56 C. nigricans Gang., 57. C. picturata (Lind.) K. Kochet Lind., 58. C. leucostachys Hook., 59. C. Wiotii (Morren) Reg.. 60. C. argyrophylla Hort. ex Kew Land List., 61. Stromanthe sanguinea (Hook) Lond., 62. Ctenanthe kummeriana (Morren) Eichler., 63. C. lubbersiana (Morren Eichler; and 64. Thalia geniculata Linn. Introduction Taxonomic position: According to Bentham and Hooker's General Plantarrum (1883) the Zingibereles as a whole were considered to be one family among the Mono cotyledones, under the series Epigyneae. In Engler and Prantl's Die Naturlichen Pflanzen-familien (1889) the Scitamineae were divided into four families: Musaceae, Zingiberaceae, Cannaceae and Marantaceae. Endlicher (1836-40) (after Richard 1831) divided the family into two tribes; Heliconieae and Uranieae. Schumann (1900) divided the Musaceae into three subfamilies Musoideae, Strelitzioideae and Lowioideae, and further subdivided the Strelitzioideae into two tribes; Strelitzieae and Heliconieae. Winkler (1930) extended this division by the formation of another tribe, Ravenaleae. Hutchinson (1934) raised the status of Schumann's three sub-families to those of families. Nakai (1941) recognised another family, Heliconiaceae in addition to Hutchinson's three families. Lane (1955), however, recognised Lowiaceae as a distinct family from Musaceae and this is also agreed by various workers, but divided Musaceae into two subfamilies; Musoideae and Heliconiodeae and dividing Musoideae again into three tribes; Museae, Ravenaleae and Strelit zieae. Schumann (1904) separated the family Zingiberaceae into two sub families; Zingiberoideae and Costoideae and the Zingiberoideae were further sub-divided into three tribes; Globbeae, Hedychieae and Zingibereae. Hutchin son (1934) on the other hand divided the family directly into four tribes; Costeae, Hedychieae, Globbeae and Zingibereae. Holttum (1950) made an alteration to this scheme by transferring the genus Zingiber from the tribe Zingibereae to the Hedychieae and thus the former had to be renamed as Alpineae which is, in fact, Schumann's Zingibereae without Zingiber . This view is also shared by Tomlinson (1956). 1970 A Cytological Study of the Zingiberales 15 Cytological information about the whole order was sparse except for Musaceae which had been thoroughly investigated by various workers (Agharkar and Bhaduri 1935, Cheeseman 1935-36, Cheeseman and Larter 1935, Dodds 1943, 1945, Charkravorti 1948, 1946, and Simmonds 1962). Quite a number of workers have reported on the chromosome numbers of other families (Morinaga 1929, Boehm 1931, Sugiura 1931, Gregory 1936, Benerji 1940, Janakiamal 1945, Holzer 1952 and Malik 1961). In 1943 Raghavan and Venkatasubban first published a paper on cytology of the Zingiberaceae in relation to their taxonomy. They determined the chromosome numbers of 24 species but since their technique was based mainly on the sectioning method, very little data regarding the chromosome morphology was given. Nevertheless, this work laid the foundation for later workers. Ven katasubban (1946) made a preliminary survey of chromosome numbers in 38 species of various families of the Zingiberales. Later, Chakravorti (1948, 1952) and Sato (1948) made a considerable contribution to the karyological knowledge of this group. In 1957 Sharma and Bhattacharyya attacked this problem with modern squash techniques and reported on the cytology of 9 species of Calatheae and Maranta. In 1959 they made an extensive contri bution to our knowledge of the karyology of the Zingiberaceae. One of their main conclusions was the very widespread occurrence of inconstancy in chromosome numbers in individual species. Sato (1960) made another im pressive study on the karyotype analysis with special reference to proto karyotype and stable karyotype in the Zingiberales: but the main drawback in his investigation was the use of the sectioning method which is virtually useless for studying the chromosome morphology in order to make reliable idiogram. Information about meiotic divisions is sparse, reliable information being restricted to only a few species except in Musaceae (sensu stricto) have been considerably investigated by a number of workers (loc. cit.). It is worth noting that Tomilson (1956, 1959, 1960, 1961a, 1961b) has made a thorough investigation into the anatomy of the Zingiberales and by combining his findings with the morphological characters he has brought into light many interesting and hitherto unknown facts which will prove of great assistance in classifying this group. It will be obvious from the above survey of literature that an extensive study of cytology with modern techniques is extremely desirable. The, value of not only chromosome number but also chromosome morphology as an aid to taxonomy is becoming increasingly clear and it was with the aim of employing this powerful weapon to attack this problem the present investi gation is undertaken. Preliminary studies (Spearing and Mahanty 1964) have already clearly shown the value of this method. 16 H. K. Mahanty Cytologia 35 Whilst a lot of information can be obtained from idiograms of the somatic chromosomes, but essential information about the homologies of the chromo some complements can be obtained only from the study of meiosis which, for this reason has been investigated in quite a number of species. An attempt has been made to include representatives of not only the families, but also of the sub-families, tribes and smaller sections as was possible, despite the difficulty in obtaining the living material of many forms. Materials have been obtained from Botanical Gardens all round the world and an effort has been made to obtain specimens that would shed light on karyotypic changes related to geographical distribution. Methods and materials The study of the somatic chromosomes of the Zingiberales is a matter of great difficulty because of their low stainability . After a long trial of the techniques commonly applied in plant cytology the one described below based on those of Tjio and Levan (1950) and La Cour (1941) has proved so far to be the best and has been extensively used in this investigation . Clean excised root tips were pretreated with a saturated solution of monobromonaphthalene in water for two hours . Next they were transferred to a watch-glass containing 9 drops of 2% orcein in 45% propionic acid and the watch glass was gently heated over a spirit lamp for 2-6 seconds , one d rop of NHCI was added , heating was resumed again for a few seconds and the root tips left in the mixture for one and a half hours . A root tip was then placed in a small drop of 1% orcein in 45% propionic acid on a slide , the extreme tip cut off (the proximal part being discarded) covered with a coverslip, and given a gentle tap with a blunt pencil in order to squash the growing point. Gentle tapping with a needle greatly facilitated the spreading of the cells. Uniform manual pressure was applied through a few thick ness of blotting paper, which helps to spread the chromosomes and also absorbs the excess stain.