Proc. Indian Acad. Sci. (Plant Sci.), Vol. 90, Number 2. April 1981, pp. 153-162. ~~) Printedin India. Comparative morphology and taxonomic value of foliar sclereids in Limonium Tour. (Limoniaceae) T ANANDA RAO* and SILPI DAS Botanical Survey of India, Howrah 711 003, India * Present addxess : 47/11, " Srinivas ", Mount Joy Extension, Hanurn91 Bangalore 560 019, India MS received 13 August 1979 ; revised 19 December 1980 Abstraet. Foliar sclereids in Limonium Tour. exhibits diffuse, termifial of mixed pattems of distribution. A few instances have been focussedto place on record the importance of sclereids in any future taxonomic revision of this genus. Keywords. Foliar scIereids ; Limonium ; taxonomic vaiue ; Limoniaceae. 1. Introduction Spicutar ceUs or branehed sclereids have been recorded in the mesophyll of a few taxa of the genera Aegialitis, Limoniastrum and Limonium (Abraham 1965; Solereder 1908; Metcalfe and Chalk 1957; Fraine 1916). Further details on the forro, struztttre aad distribution of foliar sclereids have been added recently (Rao and Das 1968; Bokhari 1970). The present work represents a further contri- bution to the morphology aad distribution of sclereids in 30 species of Limonium Tour. The data thus obtained have been utilised to evaluate their taxonomic value. 2. Materials and methods The materials for this study were through the courtesy of the Directors/Keepers from several herbaria, here abbreviated foUowing the symbols published by Holmgren and Keuken (1974); I-[erbarium of the Komarov Botanical Institute of the Academy of Science of USSR (LE), Prof. Popov Street, 2, Leningrad, p. 22. U.S.S.R. ; Moseow Main Botanic Garden, Academy of Seiences of U.S.S.R. (MI-lA), Moseow 127276, U.S.S.R. The names oŸ the taxa studied are arranged in alphabetieal order. 1. Limonium articulatum (Lois) O. Kuntze, Maritima province Mueller s. n. (LE). 2. L. aureUm (L.) H~II. Anon. s. n. Herb. Fiseher (LE); Mangolia, A. Rayllhya s. n. (MHA). 3. L. axillare(Forsk.) O. Kuntze, Herb. Hortt. Baton imperatis, Lertingrad. P.O)--6 154 T Ananda Rao and Silpi Das Anon s. n. (LE); Saudi AraNa, W. Diekson 562 (LE). 4. L. bahusiensis (Fr.) O. Ktmtze, Emil Almquist s. n. (LE). 5. L. bicolor (Btmge) O. Kuntze, Mongolia, B. Dashiim s. n. (MITA). 6. L. bellidifolium (Gouan) DUM. Mediterranean, Gay s. n. (MHA). 7. L. cabulicum (Boiss.) O. Ktmtze, Afghanistan, Griffith 4171 (CAL). 8. L. carolinianum (Walt.) Britton, Ganada, Nova. S:otia, Crescent beach, H. N. Zirtck 1122 (MITA). 9. L. caspium (WiUd.) Gamn. S. E. Kttt~cheroyskaya 390 (MITA). 10. L. gmelinii (Willd.) O. Kuntze, Rottmaaia, Sophia, St. Georgiev s. n. (MHA); Fischer s. n. (LE). 1 i. L. meyeri (Boiss.) O. Ktmtze (= S. gmelinii Willd. var. laxiflora Boiss.) Persian bay, Szovits 60d (LE). 12. L. humile Mili., British isles, Bangor, Angtesey, P. W. Richards 52(MITA). 13. L. nash¡ Small, Ganada, Qttebec. P. Louis- M~rio 34459 (MI-IA). 14. L. piptopodum Nevski, Mediterranean, G. Pro;kuriakova s. n. (MHA). 15. L. pubescens (DG.) Oi Kuntze, Algiers Anort. s. n. (LE). 16. L. reniforme (Girard) Lincz, Uzbikistan, A. Kohokchziakn s. n. (MITA). 17. L. reniflorum O. Kuntze, Scandanevia, Anderson s. n. (LE). 18. L. sareptanum (Becker) Gato% Anon. E. Salomon s. n. (LE); N. A. Lcaiova s. n. (MI-IA). 19. L. sinuatum (L.)Mili. Dalgerie, P. Jamin 1850 (LE). 20. L. semenovii (I-Ierd) O. Kuatze, Kazikstan, V. Goloskokov s. n. (MHA). 21. L. stocksii (Bois~.) O. Kuntze, India, Saurastra, Porbtmder, B. Sal'tU 2473 (CAL); Diu Island, T. A. Rao 1965 (CAL.). 22. L. suffruticosum (L.) O. Ktmtze, M. Ehmanola 755 (MITA); Germany, Anon s. n. (LE); Fischer 178 (LE). 23. L. tenellum (Tucz.) O. Kuntze, Mangolia, M. L. Legrov s.n. (MHA). 24. L. thouinii (Viv.) O. Ktmtze, Algeria, B. Balansa 403 (LE); Egypt, Alexandria, C. G. Ehrertbeng s. n. (LE). 25. L. tomentellum (Boiss.) O. Kuntze, Wender- lick 93 (LE). 26. L. virgatum (Willd.) Fourr, Italy, A. Bioudi (LE); Barcelona, I-I. Motuin s. n. (LE). 27. L. vulgare Mill., Denmark, Jylland K. Wunstedt. s. n. (MHA). 28. L vulgare Mil/. ssp. serotinum (Rchb.) Gatos, France, Arles, F. ttop¡ s. n. (MITA). 29. L. vulgare Mili. ssp. humile (Mili.) Gatos, Dapla Ex. tterb. Musci. ttist. Naturhistorisches Mttseum, Wein. (MI-IA). 30. Limonium sp. Lusitania, Welwitoch 1160 (LE). The clearing techniqtte is after Foster (1955) and the classification of sclereids is after Rao and Bhttpal (1973). 3. Observations A study of the cleared [eav~, hand sections and macerations reveal=d that foliar sCl91 c~n be sorted out from a purely positional relatinnship with voinlet endings into diffaso, terminal or mixod patt=rns. Diffuse scl91 have boen notir irt L. aureum (L.) ttiU, L. axillare (Forsk.) O. Kuntzo, L. bicolor (Bunge) O. Kumze, L. gmelinii (WiUd.) O. Kumze (figure 12), L. suffruticosum (L.) O. Kunt.ze, L. virgatum (WiUd.) Fourr. (figure 13). Terminal sclereids have been noficed in L. articulatum (Lois.) O. Kuntze, L. cabulicum (Boiss.) O. Kuntze (figure 10), L. pubescens (DG.) O. Kunt~e, L. stocksii (Boiss.) O. Kuntze (figures 1-3), L. vulgarae Mil1. (figure 6) and L. vulgarae ssp. serotinum (Rehb.) Ganas. Mixeat patt~rn of distribution of sclereids observed in L. meyeri (Boiss.) O. Kuntze and 1]. tamentellum (Boiss.) O. Kuatze (figures 4, 5 and 15). Foliar sclereids in Limonium 155 I IOO~U 'i Figures 1-3. 1. Transection of lamin~ of Limonium stocksii (Boiss.) O. Kuntze (Ra.o T A 1965, CAL) showing fttsiform a.nd ra,miferm sclcreids dispersed in the palŸ aad a fr in coatact with vascular bund[e. 2, 3. M~oerated scir of L. stocksª *. don$ing to polymorphir grouping. 156 T Ananda Rao and Silpi Das Figures 4-5. 4. Transection of lamina of Limonium tomentellum (Boiss.) O. Kuntze (Wenderlick 93, LE) showing rhizosclereids in the palisade in eontact with vascular veins and diffuse ramiform sclereids in the spongy region. 5. Fusoid to polyrarnous sr of Limonium tomentellum. Foliar sclereid~ in Limonium 157 :~ii/Ji:!): ~:} ) 6 r---- -f 200/12 Figure 6. Transeetion of lamina of L. vulgare Mili. showing the clase relationship of sdereids and veins. Asa contrast to the above fiadiags veirt-end• devoid of sclereids were eneountered in the terminal of L. bahusiensis (Fr.) O. Kuntze, L. bellidifolium (Gamen) DC., L. carolinianum (Walt.) Britton, L. caspium (WiUd.) Gatos, L. humile Mili., L. nashii SmaU., L. piptopodum Navski, L. reniforme (Gizard) Lincn, L. reniflorum O. Kuntze, L. sareptanum (Beeker) Ganas, L. sinuatum (L.) Mill., L. semenovii (Haxd) O. Kuatze, L. tenellum (Turcz.) O. Kuntze, L. thouinii (Viv.) O. Kuntze and L. sp. 3.1. Typology Irre;pective of their positional relationship with the vein-endings the foliar sclereids can be classified into the following types. Since the types ate already described in detai[ (Rao and Das 1968; Bokhari 1970) a summary of the types has been outlined below. 3. la. Fusiform sclereids : They have a spindle-shaped base form with fusoid ends which are straight or sometimes bent curiously into C-shaped, V-shaped or sigmoid-shaped and fotmd scattered in the mesophyll either parallel to the leaf- sttrface or vertically disposed in the palisade region. Structurally they exhibit two forro variations confin.ed mainly to the thickentng of cell-wall : fusiform with thin cell-wall and wide htmen of uaiform width or thick striated and pitted cell-wall and narrow lumen. 158 T Ananda Rao and Silpi Das 3. lb. Rhizosclereids : It is not uneommon to observe fusiform sclereids ha~ing a tendeney to branch at one end. Such branehes are attenuated and gire a root- liko app~~raace (figures 2, 3). Structurally they huye a columnax body with tendeney to fork irregularly at one end only. The cell-wall is thick, striated, pitted and the htmen is more or less uniform. 3. le. Ramiform sclereid : Tlais has the base form of a rhizosclereid with forking or rooting branches at both the ends. The branehes are dichotomous of trichoto- mous with limited extensions. The cell-waU is relatively thick, often pitted and possesses lumen of u~iform width in the main column and also in the branehes. Apart from sclereids the other interesting significant morphological features of the lamina are the presente of brachy and selerotracheoids at the vein-endings aad formation of seleroeysts encasing the vasculature at the basal and mid-region of the laminae in a few t91 namely L. stocksª and L. cabulicum (figures 8-11). In the majorities of the investigated species, ir has beea found that the terminal vein-endings huye slightly thickened ceU-wall and dilated brachytracheoids in groups, possessing thick cell-wall and prominent helical thickenings. They are disposed paraliel to the lamina or vertieaUy to the leaf-surface. 3. ld. Polyramous sclereids : They huye the base forms of ramiform sclereids with extended, regular or irregttlax branches of equal or unequal length. The eell-waU is thiek, striated and sometimes tuberculate or undulated or sinuous. This diversity gives a curious appearance to these types of idioblasts. 3. le. Spheroidal sclereids: Spherical or semi-spherical or oval-shaped, thick- walled with or without pits are often seen at the basal region of the laminae. They ate mosfly isolated and found in the vicinity of major veins. 3. lf. Tracheoids: Ir is not uncommon to observe the presence of terminal brachytracheoids or sclerotracheoids at the vein-endings in the laminae of L..tomentellum (figure 14) where mixed pattern of sclereids are also encotmtered (Rao aafl Bhupal 1972). 4. Taxonon¡ value The taxonomic treatment of Limonium us described by Boissier (1848) and the present study on the distribution of sclereids in various sections, sub-sections and individual t91 deserve futl attention in any future revision of this genus.