Cytologia 49: 613-627, 1984

Cytological Observations on Some West Himalayan Orchids Tribe: Epidendreae III (Subtribes: Crytopodiinae, Cymbidiinae, Sarcanthinae)

P. N. Mehra and S. K. Kashyap

Botany Department, Panjab University, Chandigarh, India

Received October 20, 1982

This third and last paper of the present series on Epidendreae gives the cyto logical information on 16 species belonging to 12 genera spread over subtribes Cyrtopodiinae, Cymbidiinae and Sarcanthinae. The taxa of these subtribes have a great horticultural potential because of their very fascinating flowers. Hybridiza tion work on the members of Cymbidiinae as well as Sarcanthinae is very much in progress in different parts of the world.

Material and methods

Materials were collected from nature in the Western Himalayas. Chromosomal

studies were made from pollen mother cells (PMC's), embryo-sac mother cells

(EMC's) and from root tips. Karyotypic analysis was done in some members. The methods and techniques adopted are the same as described earlier (Mehra and

Kashyap 1983). Photomicrographs are at uniform magnification of •~1510 except

where otherwise stated. Voucher specimens are deposited in the Herbarium of the

Botany Department, Panjab University, Chandigarh.

Results and discussion Table 1 summarises the results of present investigation. Some notes are ap pended for individual taxa. Subtribe: Cyrtopodiinae Bentham Eulophia R. Br. ex Lindl. This genus comprises 200 pan-tropical terrestrial species (Airy Shaw 1973). In most of the species, flowers and leaves appear at different times. E. campestris Wall. is widely distributed along the lower elevation of Western Himalayas growing in open grassy places at an altitude of about 300m. Tubers are believed to form the bulk of the commercial product known as 'Salep-misri'. It flowers during March-April. Meiotic studies from PMC's showed 24 bivalents at M-I, and M-II (Fig. 1). The present count falls in line with the only report of n=24 by Vij et al. (1976a). The genus has wide range of chromosome numbers viz., 2n=32, 38, 54 and 56 (Sampathkumaran and Rangaswamy 1931, Chatterji 1965, Tanaka 1965, Pancho 1965, Mehra and Vij 1970). It is difficult to comment on its basic number at the Table 1. * Species worked out for the first time . + New chromosome number added/B-chromosomes . 616 P. N. Mehra and S. K. Kashyap Cytologia 49 present state of our knowledge. AR-Rushdi (1971) has observed n=20, 22, 23, 31 and possibly 24 for Eulophia. Oreorchis indica Hook. f. It is a terrestrial species met with in moist situations at an altitude of about 2200m. Somatic determination from root tip mitosis re vealed 2n=42 (Fig. 2). Chromosomes are small and appear to possess median or submedian primary constriction. The species is investigated for the first time. The only other species of this genus O. patens is known to possess 2n=48 (Ono et al. 1957, Mutsuura and Nakahira 1959) and 2n=50 (Tanaka 1965) chromosomes. On the basis of this information, it is difficult to decide the basic chromosome number for the genus. Dressier (1974) has merged the subtribe Cyrtopodiinae into Cymbidiinae which seems unjustified on the basis of number and morphology of chromosomes.

Subtribe: Cymbidiinae Bentham

The subtribe is horticulturally important. It includes 11 genera (Dressier and Dodson 1960) of which only 5 have been investigated cytologically (cf. Tanaka and

Kamemoto 1972, 1974). Colchiploids, hybrids and horticultural varieties are known at the triploid, tetraploid and pentaploid levels. Cymbidium Sw. The genus is of great ornamental value and includes more than

40 epiphytic as well as terrestrial species distributed in tropical Asia and Australia

(Airy Shaw 1973). C. giganteum Wall. grows as an epiphyte in the thick moist forests in the

Kumaon hills at about 1300 m. Chromosome number from root tip mitosis re vealed 2n=40 (Fig. 3). They exhibited gradual size gradation and measured from 3.44-1.98ƒÊ. Total chromosome length is 41.83ƒÊ. The karyotype consists of 30m+8sm+2st chromosomes (Fig. 22).

The present count 2n=40 is in agreement with the reports by Mehlquist (1952),

Wimber (1957), Sharma and Chatterji (1966) and Vij and Mehra (1976). Wimber

(1966) considered x=20 as the basic number for the genus Cymbidium which is of common occurrence in the species so far investigated (cf. Tanaka and Kamemoto

1972, 1974). Mehra and Sehgal (1978), however, reported n=19 and 2n=42 in some species which appear to be of secondary origin.

Subtribe: Sarcanthinae Bentham Sarcanthinae is one of the most horticulturally important subtribes since its members possess beautiful showy flowers. It includes 106 genera distributed in the tropical and subtropical regions of the old world including Malaya, Eastern India, Phillipines, China and Japan. Not much work has yet been done on this subtribe; only about 39 genera are reported cytologically which comes to about 36%. Some workers like Tara and Kamemoto (1970) and Shindo and Kamemoto (1963a, b, c, d) have undertaken karyotypic analysis of some of its members . Presently 12 species falling under 9 genera have been studied. All the members have advanced type of pollinia, each pollinium being surrounded by a waxy wall. Acampe papillosa Lindl. grows as an epiphyte at lower elevations of about 700m. Somatic studies from root tip mitosis revealed 2n=36 . Chromosomes 1984 Cytological Observations on Some West Himalayan Orchids 617 appear to have median or submedian centromere. The present count confirms the haploid number n=18 reported by Mehra and Sehgal (1978), who also found a cytotype with n=19 from the Eastern Himalayas. The cytotype with 2n=38 was also reported earlier by Vij and Mehra (1976) from the same area. Kamemoto et al. (1964) and Tara and Kamemoto (1970) also reported n=19. In all, only three species are known cytologically and all are built on 2n=38. The possible basic number of the genus is x=19 and the present taxon seems to be an aneuploid.

Aerides Lour.

A genus of much ornamental value, comprising 40 species and chiefly distributed in India, Indochina, Japan and Malaysia except New Guinea (Airy Shaw 1973).

In the Western Himalayas the genus is represented by 2 species only, both of which have been studied presently.

A. multiflorum Roxb. grows commonly as an epiphyte on mango trees from Dharamsala onwards to Kumaon hills at lower levels ascending up to 1300m. It has beautiful pink-flowered drooping inflorescences which appear during April

June. Nineteen ring-and rod-shaped bivalents were seen at M-I (Fig. 4). Non conjugating chromosomes were also observed in about 15% cells. Meiosis was normal.

Somatic count revealed 2n=38 chromosomes from root tip mitosis. Chromo somes are small and appear to possess median or submedian primary constriction.

The earlier reports of n=19 by Arora (1968) and Vij and Mehra (1976) are thus con firmed. However, Sharma and Chatterji (1966) reported 2n=40 for the species.

A. odoratum Lour. is also met with as an epiphyte at lower levels in the Doon valley and Kumaon hills. It too has a great ornamental value, flowering during

April-May.

The chromosome number was determined from PMC's which revealed n=18

at diakinesis (Fig. 5). Some of the bivalents showed early disjunction. Meiotic course was normal. This number was further confirmed from root tip squashes

which revealed 2n=36. The present finding is at variance with the previous ones

2n=38, 40 (cf. Tanaka and Kamemoto 1972, 1974) and seems to represent an aneu

ploid taxon. About 18 species belonging to this genus are known cytologically so far. Out

of these only four have been found to possess 2n=40 while all the rest have 2n=38

(cf. Tanaka and Kamemoto 1972, 1974, Moore 1973) with the exception of the

present taxon which has 2n=36. Darlington and Wylie (1955) suggested x=19, 20 as the basic numbers for the genus.

Cleisostoma micranthum K. and P. is an epiphyte distributed in the Kumaon hills between 800-1100m. Its flowering period is April-May.

PMC's revealed n=19 at diakinesis (Fig. 6). Bivalents are both ring and rod shaped. Meiosis was normal. The gametic chromosome number was further confirmed from root tip mitosis which showed 2n=38 chromosomes (Fig. 7). The

chromosomes have slight gradation in size and range from 1.58-1.05ƒÊ. Total 618 P. N. Mehra and S. K. Kashyap Cytologia 49

Figs. 1-9. Eulophia campestris: 1, PMC at M-II showing n=24. Oreorchis indica: 2, somatic cell with 2n=42 at metaphase. Cymbidium giganteum: 3, somatic cell with 2n=40 at metaphase. Aerides multiflorum: 4, PMC with 19 bivalents at diakinesis. A. odoratum: 5, PMC with 18 bivalents at diakinesis. Cleisostoma micranthum: 6, PMC with 19 bivalents at diakinesis. 7, somatic cell with 2n=38. Gastrochilus calceolaris: 8. PMC with 19 bivalents at diakinesis. 9, abnormal sporad. 1984 Cytological Observations on Some West Himalayan Orchids 619

chromosome length is 47.68ƒÊ. Karyotype consists of 24m+6sm+8st (Fig. 23). The present counts n=19, 2n=38 are in line with the observations of Mehra and Vij (1970) and Vij et al. (1976a). In some species of the genus Cleisostoma Mehra and Sehgal (1978) reported n=20, 21 which appear to be of secondary origin.

Gastrochilus calceolaris Don. grows epiphytically at an elevation of 800m in Dehra Dun, ascending up to 1400m in Kumaon hills. Its flowering period is

March-April. Meiotic studies revealed n= 19 at diakinesis (Fig. 8). In a few mother cells n=18 was also observed at M-I. A few bivalents showed early dis junction at diakinesis. Secondary associations at M-I were noticed in about 25 cells. Presence of abnormal tetrads (Fig. 9) suggests aberrant meiosis. Pollen mitotic metaphase revealed n=19 (Fig. 10). Mitotic study from root tip squashes also showed 2n=38 (Fig. 11). Variable numbers 2n=34, 38 and 40 are reported for different species of this genus (cf. Tanaka and Kamemoto 1972, 1974). Only x=19 in all probability is the real basic number and the others like n=17, 20 may be secondary in origin.

Doritis Lindl. The genus comprises only 5 species which are distributed from India to West Malaysia (Airy Shaw 1973). Doritis taenialis Bentham is of ornamental value and grows in the Kumaon hills as an epiphyte mostly on oak trees at about 1500m. Its flowering period is May-June. Presently it is found to occur in two cytotypes, diploid and triploid. Cytotype with n=19: Meiotic studies from EMC's revealed 19 bivalents at M-I (Fig. 12) with 7-8 bivalents somewhat smaller than the rest. Cytotype with 2n=57: Somatic number determination from root tip showed 2n=57 (Fig. 13). Both the cytotypes grow mixed in the same population. The triploids have longer roots (about 1m) and more flowers compared to the diploid. Roy and Sharma (1972) reported 2n=40 for this species, while Chatterji (1965) reported 2n=40, 60. Vij and Mehra (1976) recorded n=19. Two more species of the genus are known cytologically e. g. D. buyssoniana with 2n=76 (Woodard 1951) and D. pulcherrima with n=19, 2n=38 (Woodard 1951, Sagawa and Niimoto 1961, Shindo and Kamemoto 1963e, Chardard 1963 and Kamemoto et al. 1964). A te traploid taxon with 2n=76 is also on record (Kamemoto et al. 1964) in D. pulcherrima. On the basis of these studies alongwith present one, x= 19 is the true basic number for this genus and n=20 seems to be derived.

Luisia Gaud. The genus comprises 30 species, distributed from tropical Asia to Japan and Polynesia (Airy Shaw 1973) of which 2 species have been presently investigated. L. inconspicua Hook. f. grows as an epiphyte at a lower elevation of about 800m in the Kumaon hills. Its flowering period is July-August. Gametic chromosome number was determined from PMC's which revealed n=19 at M-II (Fig . 14). Laggards were observed at A-II. Dyads, triads, monads were also seen alongwith normal tetrads. The present counts n=19, 2n=38 are in 620 P. N. Mehra and S. K. Kashyap Cytologia 49 harmony with the report by Mehra and Vij (1970), Vij and Mehra (1976) and Mehra and Sehgal (1978). L. trichorhiza Bl. is a terete-leaved species like the previous one. It grows epiphytically in the Kumaon hills and in Doon valley at 900-1100m. Flowering period is April. Meiotic studies revealed n=19 at diakinesis (Fig. 15). Some of the smaller bivalents showed precocious disjunction. Meiosis was normal. Root tip

Figs. 10-18. Gastrochilus calceolaris: 10, pollen mitotic metaphase with n=19. 11, somatic cell showing 2n=38. Doritis taenialis: 12, EMC with n=19 at M-I . 13, somatic cell showing 2n= 57 chromosomes. Luisia inconspicua: 14, M-II with n=19 at one pole. L. trichorhiza: 15, PMC with 19 bivalents at diakinesis. Ornithochilus fuscus: 16 , somatic cell with 2n=38 at metaphase. Rh ynchostylis retusa: 17, PMC with n=19 at M-I. 18, somatic cell with 2n=38 at metaphase . 1984 Cytological Observations on Some West Himalayan Orchids 621 mitosis showed 2n=38 chromosomes. The present counts n=19, 2n=38 for the species are in conformity with Jones (1967), Vij and Mehra (1976) and Vij et al. (1976b). An aneuploid number n=20 was given by Arora (1968). Only 5 species under this genus are known to possess n=19, 2n=38, while in some species n=20, 2n=40 are also in record (cf. Tanaka and Kamemoto 1972, 1974). Darlington and Wylie (1955) suggested x=20 for Luisia.

Figs. 19-22. Vanda cristata: 19, somatic cell with 2n=38. 20, somatic cell with 2n=76. V.

parvifiora: 21, PMC with n=19 at diakinesis. Cymbidium giganteum: 22, karyogram of figure 3. 4530. •~

But x=19 appears to be the primary basic chromosome number and x=20 may be of secondary origin. Ornithochilus Wall. is a monotypic genus represented by o. fuscus Wall. distri buted from India to Burma, Siam and China (Airy Shaw 1973). It grows as an epiphyte in shady and moist situations at about 1300m in the Kumaon hills. Gametic chromosome number was determined from PMC's which showed n= 622 P. N. Mehra and S. K. Kashyap Cytologia 49

19 at diakinesis. The complement has both ring and rod-shaped bivalents. Meio sis was normal. Somatic studies revealed 2n=38 from root tip mitosis (Fig. 16).

Chromosomes showed size gradation and measured from 1.72-0.79ƒÊ within the com plement. Total chromosome length is 46.62ƒÊ. Karyotype consists of 26m+ 8sm+4 st as seen in the karyogram (Fig. 24).

The present counts n=19, 2n=38 are in accord with the previous reports of

Sharma and Chatterji (1966) and Vij et al. (1976b). For this monotypic genus x=l9 is the basic number.

Rhynchostylis B1.

Although this horticulturally important genus contains 15 species distributed in

China and Indomalayasia (Airy Shaw 1973), it is represented by a single epiphytic species in India. R. retusa Bl. found in the foothills of Western Himalayas, also extending to

Eastern Himalayas. It has beautiful drooping inflorescences with light pinkish white flowers which appear in April-May. Nineteen rod-shaped bivalents were observed at M-I (Fig. 17). Non-congres sion of some bivalents was observed at this stage in about 15% cells. Meiotic course was by and large normal. Somatic studies from root tips showed 2n=38

(Fig. 18) chromosomes which showed regular size gradation and measured 2.11 0.79ƒÊ within the complement. Total chromosome length is 56.42ƒÊ. Karyotype- is symmetrical with 34m+4sm as seen in the karyogram (Fig. 25).

The present findings of n=19, 2n=38 are in line with the earlier reports (Arora 1971, Vij and Mehra 1976, Kamemoto et al. 1964 and Tara and Kamemoto 1970).

The basic chromosome number x=19 is suggested for this genus.

Vanda R. Br. This horticulturally important genus embraces 60 species, distributed in India, China, Indomalayasia and Marianne Islands (Airy Shaw 1973). Only 4 species are reported from the Western Himalayas (Duthie 1906). Many interspecific and intergeneric hybrids of Vanda are known (cf. Tanaka and Kamemoto 1972, 1974). Only 2 species have been worked out presently. V. cristata Lindl. grows as an epiphyte forming thick clusters on oaks in the Kumaon hills between 1200-1500m. The flowering period is from May-June. Two cytotypes with chromosome numbers n=19, 2n=38 and 2n=76 were noticed presently. Diploid cytotype with n=19, 2n=38: Meiotic determination from PMC's re vealed n= 19 at diakinesis. Early disjunction was noticed in some of the bivalents. Meiotic course was normal. Somatic studies revealed 2n=38 from root tip mitosis (Fig. 19). Chromosomes appear to have mostly median or submedian centromere. Tetraploid cytotype with 2n=76: Somatic studies from root tip mitosis reveal ed 2n=76 (Fig. 20) chromosomes. The report of a tetraploid taxon (2n=76) in the species is new. V. parviftora Lindl. grows as an epiphyte in the Doon valley at about 700m, flowering in May. 1984 Cytological Obesrvations on Some West Himalayan Orchids 623

Figs. 23-25. 23, karyogram of figure 7 (Cleisostoma micranthum). 24, karyogram of figure 16

(Ornithochilus fuscus). 25, karyogram of figure 18 (Rhynchostylis retusa). All•~4530. 624 P. N. Mehra and S. K. Kashyap Cytologia 49

Meiotic studies revealed n=19 at diakinesis (Fig. 21). Bivalents were ring and rod-shaped. Non-congression of some of the bivalents was common at M-I. Dyads, and triads were also seen. Unequal distribution of chromosomes was observed during the formation of tetrads leading to unbalanced spores. This count of n=19 was earlier reported by Mehra and Kashyap (1976) and later confirmed by Vij et al. (1976a). Jones (1963) reported 2n=ca. 40. To date about 24 species of Vanda are known cytologically. Majority of them possess n=19, though other numbers n=ca. 16, ca. 18 and 20 are also reported by some authors (cf. Tanaka and Kamemoto 1972, 1974). Darlington and Wylie (1955) suggested x==19 as the basic number for Vanda which seems most logical. The genus has many polyploids and aneuplids. The subtribe Sarcanthinae is considered as the most advanced among the Orchidaceae. Almost all the members have small or medium-sized chromosomes, monopodial habit, specialized type of pollinia and are easily prone to hybridization. The chromosome number in all the presently studied taxa, alongwith those mention ed in the literature, reveals n=19, 2n=38 as the most common number (see also Ta naka and Kamemoto 1972, 1974). Presently a triploid cytotype with 2n=57 in Doritis taenialis and a tetraploid one with 2n=76 in Vanda cristata have been found to be new. It is concluded that x=19 is the real basic number for the entire sub tribe Sarcanthinae. All other numbers may have had secondary origin in the pro cess of evolution and speciation. Dressler has recently (1974) raised this sub tribe to tribal rank which the subtribe possibly deserves.

General discussionon Epidendreae While the chromosome number generally is the same, n=20, there is definite phylogenetic reduction in chromosome size in the Bletiinae, Thuniinae, Coelogyni nae and Epidendrinae alliance. This is extremely clear from the karyograms of the representative members of Bletiinae (Calanthe tricarinata) and of Coelogyninae (Coelogyne cristata and Pholidota articulata) assembled in Figs. 17-19 (Mehra and Kashyap, this journal). The chromosomes in the first two subtribes Bletiinae and Thuniinae are comparable in size to members of the Orchideae and some of the members of Neottieae. Also it is striking that Bletiinae and Thuniinae comprise ground-growing orchids like the latter two subtribes. However, Coelogyninae and Epidendrinae have taken to epiphytic mode of life and this is correlated with the reduction in chromosome size. Also they are phylogenetically more advanced than Thuniiinae and Bletiinae. Undoubtedly both Liparis and Malaxis have heterogenous assemblage of forms varying both in chromosome numbers as well as in size and need careful scrutiny to organize and split these two genera into more natural groups . In this the mor phological features in the various taxa have to be given due importance in such segregation. However, some of the members of the Liparis and Malaxis show the primitive character of somewhat large size of the chromosomes. Furthermore it is appropriate to raise the genus Oberonia into a separate subtribe Oberoniinae because of the consistent basic number n=15 of its constituent species and a near uniformity 1984 Cytological Observations on Some West Himalayan Orchids 625 of their chromosome size. As stated in the text this is in line with the suggestion of Mehra and Kaushik (unpublished work) made on the basis of their anatomical studies. Dendrobiinae has experienced phylogenetic reduction in chromosome size and strikingly it has almost exclusively epiphytic mode of existence. In the genus Dendrobium there is an assemblage of forms with relatively larger chromosomes (cf. D. chrysanthum) and rather minute ones (cf. D. bicameratum). The genus which is at present constituted of an overwhelmingly large number of species could better be segregated into more natural assemblages. However, the chromosome number in the Dendrobiinae consistently remains n=19 or 20. In Cymbidiinae the chromosomes are moderately large in size (cf. Cymbidi um giganteum) but in Sarcanthinae there is a tendency to reduction in size which will be evident on a scrutiny of the chromosomes of Cleisostoma micranthum, Gastro chilus calceolaris and Ornithochilus fuscus. Both of these subtribes are closely re lated. It is also interesting to note that while Cymbidiinae comprises members both terrestrial and epiphytic, in Sarcanthinae the epiphytic habit is the rule. Here again there is a correlation between relatively large chromosomes and terrestrial habit and a trend towards reduction in chromosome size on the assumption of epi phytic mode of life. It may as well be stated that while the basic number in Cymbidi inae is predominantly n=20, in Sarcanthineae there is wobbling of one chromosome, the number varying from 20 to 19, with the latter number being the most predom inant. It is also worthy of note that the chromosomes at meiosis in the PMC's give an appearance of being larger than the mitotic chromosomes. Furthermore the bi valents at male meiosis in PMC's are relatively larger than those in the embryo-sac mother cells. In conclusion we are inclined to think that it would be more appropriate to follow Lindley who originally splitted the epidendrous group of plants into 3 tribes Epidendreae, Malaxideae and Vandeae which appear to us natural, rather than lump all these into a single comprehensive tribe Epidendreae as done by Dressler and Dodson (1960).

Summary

Cytological investigations were carried out in 16 species included in 12 genera of Epidendreae. One species of the genus Oreorchis (O. indica: 2n=42) is investi gated for the first time. New chromosomal reaces were discovered in Aerides odoratum (n=18), Doritis taenialis (n=19, 2n=57) and Vanda cristata (2n=38, 2n= 76). It is concluded that the comprehensive tribe Epidendreae (sense Dressler and Dodson) should really be split into 3 distinct tribes Epidendreae, Malaxideae and Vandeae as originally proposed by Lindley. In each of these alliances there is gradual reduction in size of chromosomes from the more primitive to the advanced ones with the adoption of epiphytic mode of life from the original terrestrial base. 626 P. N. Mehra and S. K, Kashyap Cytologia 49

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