Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 63. (Budapest 1971)

Kováts, D.: Some histological observations on Lihospermum purpureo-coeruleum L. seedlings

ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 63. PARS BOTANICA 1971. Some Histological Observations on Lithospérmum pupureo-eoerulcum L. Seedlings By D. KOVÁTS, Budapest The plant Lithospérmum purpureo-coeruleum L. is a characteristic herb of the dry, calciphilous oakwoods on carbonate substrates and of a Submediterranean climate in our Central Range and adjacent regions (ZÓLYOMI, 1963). As a perennial plant propagating by stoloniferous means, its spreading has also a phytosociological importance in the coenologic pattern and polycormon formation (PRÉCSÉNYI, FEKETE, SZUJKÓ — LACZA, 1967). Many authors have treated, and are still discussing, the coenological conditions of this plant. Thus also in our Institute, SZUJKÓ —LACZA and FEKETE investigate, besides also other plants, its connections with the habitat factors (SZUJKÓ—LACZA, FEKETE, 1971), production, entogenesis and in this respect also chlorophyll content. In the course of these investigations a number of unclarified problems have arisen, apparently requiring an anatomic approach. The general, overall histological characterization of the Boraginaceae has already been given in the great anatomic works (SOLEREDER, 1899, 1908; METALF & CHALK, 1950). These authors treated rather the exotic, lignifying species. Certain histological aspects of the genus Lithospérmum was discussed already by JODIN (1903), but a great number of unclarified problems still remain. It were these considerations which instigated me to study this plant histologically. Although the work is still far from being completed, I still deem some of the observations made heretofore worthy of publication. In the followings, I propose therefore to dicuss briefly the root, hypocotyl and epicotyl stems, with special regard to the development of the vascular tissue system and primarily that of the xylem, of the seedlings of Lithospérmum purpureo-coeruleum L. Material and method Investigations were made on seedlings of diverse age (2 — 8, 14, 19 and 35 days old seedlings). As a plant proliferating notably by vegetative means, to induce germination presented grave difficulties. The hard shell of the nutlet, representing a mechanical obstruction, was carefully broken, and, after the removal of the outer cover of the seed (probably containing substances inhibiting germination), the seeds were induced to germinate on filter-paper. The approximately two weeks old seedlings were then transplanted into soil (Pl. I, Fig. 4). To obtain slides, the seedlings were fixed in NAVASIN'S fixing mixture. Manual and microtomic slides were made, vezuvine-malachite green staining applied, and the slides made permanent in watery glycerine. Morphological observations The general external morphologic characterization of the seedlings can be found in JODIN'S (1903) and CSAPODY'S (1968) works. According to JODIN, the cotyledons of the genus Lithospérmum are hispid only on their upper surface. Those of my seedlings were hispid also on the underside of the leaves, but less so as on the upperside. Thus JODIN'S statement cannot be accepted categorically.