Cytological Studies in Some Central and Eastern Himalayan Grasses I

Cytologia 40: 61-74, 1975 Cytological Studies in Some Central and Eastern Himalayan Grasses I. The Andropogoneae P. N. Mehra and M. L. Sharma Depatrment of Botany, Panjab University, Chandigarh, India Received May 10, 1973 Though comparatively of recent origin, the Andropogoneae is regarded as a highly specialized tribe of the grass family (Bews, 1929, Hartley 1950). Its repre sentatives occur in all latitudes under a wide range of soil and climatic conditions. In the Indian sub-continent, the tribe is represented by about 64 genera and 380 species (cf. Bor 1960). Mehra, P.N. et al. (1968, 1970) have made a detailed cytological study of the North Indian grasses and reported chromosome numbers for about 200 species, of which 40 belong to the tribe Andropogoneae. These authors have also presented a phylogenetic scheme of evolution of the various tribes, including Andropogoneae, of the grass family. The present paper presents data on 50 taxa of this tribe from the hills of Dar jeeling (E. Himalayas) and Nainital (C. Himalayas). These results are likely to help in the understanding of evolution of this tribe and laying basis for the improve ment of grasses for economic exploitation. Material and methods Collections for meiotic studies were made from the wild populations growing in the hills of Darjeeling and Nainital and the near by suburbs within an altitudinal range of 220-2600m. Material for meiotic studies was obtained from unopened inflorescences and the fixations made in Carnoy's fixative. After 24 hours, the fixed material was usually transferred to 95% alcohol. The anthers were subse quently squashed in 1-2% acetocarmine. The slides were made permanent in eu paral. Photomicrographs were taken at a uniform magnification of •~1500. Pollen fertility refers to morphologically normal pollen which stained with acetocarmine. All the identifications were checked at the Herbarium of the Forest Research Institute, Dehra Dun. These were further confirmed by late Dr. N. L. Bor of Kew Gardens. The voucher specimens were deposited in the Herbarium of the Department of Botany, Panjab University, Chandigarh, India. Observations Table 1 summarises the results of observations on 50 taxa belonging to 44 species. In the succeeding pages only the interesting features in some of the species and an account of the comparative morphology of polyploid races of five species is presented. 62 P. N. Mehra and M. L. Sharma Cytologia 40 Table 1 1975 Cytological Studies in Some Central and Eastern Himalayan Grasses I 63 Table 1 Continued 64 P. N. Mehra and M. L. Sharma Cytologia 40 Table 1 Continued 1975 Cytological Studies in Some Central and Eastern Himalayan Grasses I 65 Table 1 Continued ** Genus worked out for the first time. * Species worked out for the first time . + New report for the species (new cytotype). Literature cited in Table 1 according to Darlington and Wylie (1955), Cave et a1. (1956-68) and Taxon (1969-72). Where same chromosome number is reported by many workers, only the recent reports have been included in Table 1. Apocopis paleacea (Trin). Hochr. This grass was found forming a part of the sward on open hill sides near Ranik het. Cattle graze it greedily along with other grasses. Fig. 7 shows 7 bivalents at metaphase I. Since no other species of this genus has so far been investigated, x=7 is suggested as the base number of the genus which, it may be emphasised, is least frequent in the tribe Andropogoneae. Until some more species of the genus are worked out, it will be difficult to postulate the origin of this number. Arthraxon lanceolatus (Roxb.) Hochst. Distributed also in Deccan Peninsula. This grass is not of much use as fodder. Mehra, K. L. (1965) reported n=18 for this species whereas Mehra, P. N. et al. (1968) found n=10 as the gametic chromosome number. The present count of n=15 (Fig. 8), which is a new report, shows it to be a hexaploid based on x=5, a base number proposed by Mehra, P.N. et al. (1968) for the genus Arthraxon. A. lancifolius (Trin.) Hochr. This is a highly variable species with or without pedicelled spikelets, smooth or scrobiculate glumes of the sessile spikelets and with varying degree of hairiness of the racemes. The present count of n=9 (Fig. 9) with normal meiosis differs from the single previous report of n=10 by Khosla and Singh (1971) who also observed a tetra valent in 50PMCs and laggards at late anaphase I. 66 P. H. Mehra and M. L. Sharma Cytologia 40 Capillipediumparviflorum (R. Br.) Stapf. This grass is common in the waste places in the hills and is eaten by sheep, cattle and goats. Table 2. Capillipedium parviflorum Figs. 1-2. 1, Capillipedium parvifloum (R. Br.): n=10•{1B (left) and n=20 (right) . 2, Cymbo pogon distans (Nees.) Wats.: n=10 (left) and n=20 (right). Table 3. Cymbopogon distans 1975 Cytological Studies in Some Central and Eastern Himalayan Grasses I 67 Figs. 6-11. 6, Andropogon tristis n=10. One bivalent showing precocious disjunction. 7, Apocopis paleacea n=7. 8. Arthraxon lanceolatus n=15. 9. A. lancifolius n=9. Note secondary associations among 3 pairs of bivalents. 10, A. micans n=18. 11, Capillipedium pteropechys n=20. 68 P. N. Mehra and M. L. Sharma Cytologia 40 Two cytotypes with n=10•{1B and n=20 have been presently investigated. The diploid with n=10 was previously reported by Church (1940), Chen and Hsu (1962), Mehra, P. N. et al. (1968), whereas the tetraploid with n=20 was reported by Celarier and Harlan (1957). Khosla and Singh (1971) added a hexaploid strain with n=30. Recently, Mehra, P. N. and Remanandan (1973) have reported n=11 for this species. This is the first report of the occurrence of a B chromosome in a cytotype of this species. The distinguishing morphological features of the diploid with n= 10•{1B and the tetraploid with n=20 are presented in Table 2 (also see Fig. 1). Cymbopogon distans (Nees) Wats. This grass is distributed in the Himalayas. It contains an aromatic lemon scented oil in its tissues. Two cytotypes with n=10 (diploid) (Fig. 13) and n=20 (tetraploid) have been observed. The tetraploid was earlier reported by Mehra, P.N. et al. (1968), whereas the diploid has been recorded by Mehra, P.N. and Remanamdan (1973). The hexaploid with n=30 was reporetd by Saxena and Gupta (1970). Thus three eu ploid races are known for this species. Comparavite morphology of the diploid (n=10) and tetraploid (n=20) is presented in Table 3 (also see Fig. 2). C. martinii (Roxb.) Wats. Very common in South-east Asia. This grass possesses two forms known as ' motia' and 'sofia' which are cultivated for the sake of lemon oil. The chemical nature of the oil in the two cases, however, is different. It is difficult to separate these two forms in the herbarium but the following differences were evident in the field as earlier pointed out by Burkill (1909). Figs. 3-4. 3, Cymbopogon martinii (Roxb.) Wats.: n=10 (left) and n=20 (right). 4, Microste gium nudum (Trin.) A. Camus.: n=10 (left) and n=21 (right). In 'motia', the culm leaves make a right or obtuse angle with the culm, the grass grows in scattered patches and there are a few radical leaves at the base. In ' sofia' by contrast, the leaves make an acute angle with the culm, the grass grows in dense patches and the radical leaves are many. Var. 'sofia' is diploid with n=10 and var. 'motia' is tetraploid with n=20. The species thus occurs in two cytolo gical races. 1975 Cytological Studies in Some Central and Eastern Himalayan Grasses I 69 The count of n=10 confirms the previous report of Mitra and Dutta (1967), whereas the finding of n=20 agrees with that of Gupta (1965). The distinguishing characters of the two races are summarised in Table 4 (also see Fig. 3). Figs. 12-17. 12, Chrysopogon echinulatus n=10. 13, Cymbopogon distans n=10. 14, C. micro theca n=10. 15, C. stracheyi n=10. 16, Eulalia hirtifolia n=10. 17, E. mollis. n=9. Ischnochloa falconeri Hook. f. It is a very delicate grass which is found growing among mosses and resembles 70 P. N. Mehra and M. L. Sharma Cytologia 40 Figs. 18-24. 18, Ischnochloa falconeri n=20. 19, Microstegium nudum n=21. 20, Miscanthus nudipes n=20. 21, Mnesithea laevis n=9. 22, Sclerostachya fusca n=15. 23, Spodiopogon dubius n=10. 24, Themeda anathera n=10. 1975 Cytological Studies in Some Central and Eastern Himalayan Grasses I 71 Arthraxon lancifolius in habit and appearance. Fig. 18 shows 20 chromosomes at anaphase I. Meiosis was quite normal as also evidenced by nearly 100% pollen fertility. The genus Ischnochloa which is re presented by a single species, I. falconeri, in India has been worked out for the first time. Table 4. Cymbopogon martinii Table 5. Microstegium nudum Microstegium nudum A. Camus This grass grows commonly in hills under light shade. It is not of much use as fodder. Two cytotypes with n=10 and n=21 (Fig. 19) have been discovered. Celarier (1956a) reported n=10 for this species, whereas a count of 2n=72 was made by Avdulov (1931) and Chen and Hsu (1962). Meiosis was quite normal in both the cytotypes worked out here. 72 P. N. Mehra and M. L. Sharma Cytologia 40 A comparison of the morphological characters of these is given in Table 5 (also see Fig. 4). Sclerostachya fusca A. Camus This species was found to possess n=15 as the meiotic chromosome number (Fig.

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