Trichomes in Trifolieae II

proc. Indian Acad. S~i., Vol. 88 B, Part II, Number 5, September 1979, pp. 391-395, @ printed in India. Trichomes in Trifolieae II MOHINI GUPTA Department of Botany, Multanimal Modi Post-Graduate College, Modinagar 201 204 MS received 11 August 1978; revised 5 March 1979 Almtraet. Triehomes of nine species belonging to four genera have been studied. Orsanographie distribution of each type is given. Ontogenyof one more type has been worked out. Keywords. Trichomes; Trifolicae; Papilionaceae. 1. Introduction Gupta and Murty (1977) had earlier described the trichomes of 39 species and concluded that trichomes of Trifolieae can only help in delimitation of some species and especially the genus Ononis. To supplement the earlier infolmation, trichomes of nine more species have been studied and reported in the present paper. Material of seven species (TrifoIium alpinum L., T. montanum L., T. medium L., T. badium Schreb, Ononis repens L., O. spinosa L. and Medicago falcata L.) was procured from Ziirich and that of Trigonella gracilis Benth. and Trifolium minus Smith from Nainital and Simla respectively. The method of study followed is similar to that described earlier. 2. Observatious Out of the nine trichome types reported earlier only five are observed in the present study. Of the five types three are of nonglandular types and two of the glandular types. Table 1 shows the organographic distribution of the different types of trichomes in the different species. 2.1. Nonglandular Trichomes Three types (B, C and D) are observed. As reported earlier B type of trichome occurs only in both the species of Ononis. Each hair either contains 5-12 elongated cells as in O. spinosa or 6-9 cells as in O. repens. Apex of the hair is acuminate in both the species (figures 1, 5). 391 392 Mohini Gupta o I ........ 4 ~J e~ 9 . ~ . 0 o e. o ~ ~ ~ ~ ~ ~.~ 0 0 0 ,.o t~ "de~ 0 Trichomes in Trifolieae H 393 Figures 1-28. 1-15. Non-glandular trichomes.. 1-5. Trichome of B type. 1. From the adaxial side of the stipule of Ononis spinosa. 2-5. Various developmental stages from the adaxial side of the sepals of O. repens. 6-11. Trichomes of C type. 6. From adaxial side of the leaf of Trifolium montanum. 7-9. Various developmental stages from the abaxial side of the leaves of T. montanum. 10. from the adaxial side of the stipule of T. montanum. 11. From the adaxial side of the sepals of Trigonella graeilis: 12-15. Various developmental stages and mature hairs of D type from the abaxial side of the leaves of Medicago falcata. 16-21. Tri- chomes of H type, 16., From the stem of Ononis repens. 17-21. Various developmental stages from the standard petal and adaxial side of the stipules of Ononis repens. 22-28. Trichomes of I type. 22-27. Various developmental stages from the abaxial side of the stipules of Medicago falcata. 28. From the adaxial side of the sepal lobes of Trifolium alpinum. (Scale A for figures 1, 5, 6, 10, 11. Scale B for figures 2-4, 7-9, 12-28.) 394 Mohini Gupta 2.1.1. Ontogeny : Ontogeny of this type has been studied in O. repens. An epidermal cell functions as an initial which can be differentiated from the rest of the cells by its dense cytoplasm, larger nucleus and slightly protruded distal end (figure 2). It divides tangentially to form a basal cell and an upper cell. The upper cell divides further (figures 2-5). C type of trichome recorded here resembles in structure with trichomes reported earlier but in Trigonella gracilis (figure 11), Trifolium alpinum and T. montanum (figure 6) the stalk cells of the hair vary from one to many. In T. montanum occasionally the terminal cell is bipartite (figure 16). 2.1.2. Ontogeny: The ontogeny is studied in Trifolium montanum. The hair initial can be differentiated from the rest of the cells by dense cytoplasm, prominent nucleus and slightly larger size. The initial enlarges and divides transversely to form a basal cell and an upper cell. The upper cell elongates and divides transversely to form a small stalk cell and an elongated terminal cell (figures 7-9). In those hairs in which stalk is many celled the upper cell undergoes two or three transverse divisions and thus stalk is many celled. D type of trichomes recorded here resemble in structure with the trichomes reported earlier (figure 15). 2.1.3. Ontogeny: Ontogeny of this type has been studied in Medicago falcata. Any epidermal cell can function as hair initial and an initial cell can be differentiated from the rest of the cells by its large size, prominent nucleus and dense cytoplasm. It elongates to form a papilla and undergoes a transverse division to form a basal cell and an upper cell. The upper cell elongates and divides transversely to form a small rectangular stalk cell and an elongated terminal cell with warty projections all over the surface (figures 12-15). 2.3. Glandular Trichomes Only H and I types are observed. H type is found only in Ononis (figures 16, 21). 2.3.1. Ontogeny: Ontogeny of this type is studied in O. spinosa. The conspicuous trichome initial elongates to form a papilla and divides transversely to form an elongated upper cell with prominent nucleus and dense cytoplasm at the distal end and a basal cell (figures 17-19). The upper cell elongates and divides transversely to form a row of cells. The terminal cell of this row enlarges, becomes globular with dense cytoplasm and a prominent nucleus, which divides transversely as well as longitudinally to form a multicellular head (figures 20-21). In I type of trichome variations have been recorded in the number of cells forming the stalk. Stalk may be single celled as in Trifolium medium, T. montanum and Medicagofalcata (occasionally more celled) or more celled as in Trifolium alpinum (figure 28) and Trigonella gracilis (occasionally one celled). 2.3.2. Ontogeny : This has been studied in Trifolium alpinum and Medicago falcata. Since, all the ontogenetic stages are similar in both the species it is described here only in Medicago falcata. The prominent hair initial elongates to form a papilla and divides transversely to form a basal cell and an apical cell (figures 22-23). The apical cell divides further transversely to form a uni-, bi- er multicelled stalk and an ttpper head initial which divides to form a multicellular head (figures 24-27). Trichomes in Trifolieae H 395 3. Discussion In the nine species investigated non-glandular trichomes were reported earlier in some of the members like Trifolium badium, T. medium and T. montanum (Toma 1971), Ononis spinosa (Toma and Danis 1973). Presently non-glandulal trichomes are recorded in all the species and hairs of these species resemble in general features with the hairs reported by earlier workers. Both the species of Ononis differ from the species investigated (Gupta and Murty 1977) earlier in the number of cells forming the hair. In these species hairs with more number of cells are found. B type of non-glandular trichomes are recorded only in both the species of Ononis. Of the nine species C type is found only in Trifolium alpinum, T. montanum and Trigonella gracilis and D type in Trifolium badium, Trifolium minus and Meclieago falcata. Of the two glandular types, H type is recorded only in Ononis on all parts except stamens. I type of trichomes are only found in Trifolium alpinum, T. medium T. montanum, Trigonella gracilis and Medicago falcata. Thus by the absence of I type of trichomes Trifolium badium and Trifolium minus can be distinguished from the rest of the species. Ontogeny of trichomes is found similar in different species. As in the earlier study no correlation is found between the type of trichome and the tip of the initial cell and in the ontogeny of hairs developed on the vegetative and floral organs. Thus from the study of the trichomes of nine species, it can be concluded that only the trichomes of Ononis are of characteristic type as concluded by Gupta and Murty (1977) from 39 species. Acknowledgements The author is thankful to Prof. P K Endress (ZUrich) for providing material for the present study, and to Prof. Y S Murty, Botany Department, Meerut University, Meorut for valuable suggestions and help. Referen~ Gupta M and Murty Y S 1977 Trichomes in Trifolieae; Prec. Indian Acad. Sci. 85 77-89 Toma C 1971 Recherches de histo-anatomie comparee chez les especes de Trifolium L de Rou- manic. II. La tige; Acta Botanica, Horti Bucurestiensis pp. 187-203 Toma C and Danis E 1973 Contributii La Differentierea Morfo-Anatomica A speciilor de Ononis L. Din Flora Romaniel cu uncle consideratii de ordin ecologic; Lucrarile statiunii, Stejarul pp. 7-20 P. (B)--7 .

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