Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 65. (Budapest 1973)
Kováts, D.: Anatomical investigations on the vegetative system of Lithospermum purpureo-coeruleum L.
Rhizomes with vessel and strengthening elements multiply and strongly thickened, especially xylem ; this latter thus occupving greater part of cross-section area (Plate II, Fig. 4; Plate III, Fig. 1). Cambium forming early; generally 5-6-seriate in epigeous shoots (Plate II, Fig. 1) ; cambial rows of cells in rhizomes generally swelling to become 10 -15-seriate. Xylem In young shoots and at a primary stage, xylem of a fascicular structure, persisting for a time even after early formation of cambium. Fascicles consisting of a radially situated proto- and metaxylem row each, with 1-2-seriate parenchymatous cells between them. Fascicular structure of primary xylem indicating a fascicular formation of procambium. Subsequent to secondary elements separated by cambium, a contiguous xylem ring evolves. Xylem fascicles connected by a secondary parenchyma (according to JODIN, characteristic of the whole genus Lithospermum) . Primary xylem retaining its fascicular structure in developed, secondarily already thickened shoots with a contiguous ring already formed by secondary xylem elements (Plate II, Figs. 1, 3). Radial rows of proto- and metaxylems deeply penetrating pith parenchyma in some others, thus forming a sinuous pith crown (Plate I, Figs. 3 -4). Protoxylem vessels often deforming owing to pressure of neighbouring tissues. Also secondary xylem elements arranged more or less into radial rows, but this order frequently disturbed by some tracheae of great diameter (Plate II, Figs. 1, 3). In cross-section, width of xylem ring fluctuating between 100-250 p. Cell number of radial rows generally 10-15 (Plate II, Figs. 1. 3). Vessel diameters highly divers. On exterior side (towards cambium), vessels of secondary xylem with very small lumen, with a maximum cross-section diameter of 4-5 ft, while the tracheae of largest metaxylem and secondary xylem attaining a maximum diameter of even 25-35 p (Plate II, Figs. 1, 3). In general, tracheae and tracheids with a small lumen, quadrangular or circular in cross-sections, whereas vessels with a big lumen appearing as quinquangular or sexangular, or also rounded. CeUs walls of vessels, either with large or small lumina, of secondary xylem in Lithospermum purpureo-coeruleum L. bordered-pittedly thickened (Plate III, Figs. 2-3), while those of primary xylem vessels (large metaxylem as well as small protoxylem vessels) spirally thickened (Plate III, Figs. 2-4). — This is the reason why I cannot accept SOLEREDER'S (1899) and METCALFE & CHALK'S (1965) statements concerning the genus Lithospermum, namely that the cell walls of the smaller vessels are thickened spirally. The vessels with small lumen of the secondary xylem in Lithospermum purpureo-coeruleum L' are bordered-pittedly thickened. Since the major part of the xylem is secondary, the greater part of also the vessels have walls thickened bordered-pittedly (Plate III, Fig. 2; Plate IV, Fig. 1). The bordered pits are mostly variable (Plate III, Fig. 3; Pl. IV, Fig. 1), the pores slit-shaped. Vessel perforations usually simple (Plate III, Figs. 2-3; Plate IV, Fig. 1), but sieve-perforations also occur (in greater numbers in the roots than in the shoots ; cf. KOVÁTS — STIEBER 1972) in shoot xylems of Lithospermum purpureo-coeruleum L., as observed in Cordia Myxa by PRAEL and POMRENCKE (SOLEREDER 1899). Xylem parenchyma less developed. According to SOLEREDER (1899), the underdeveloped state of the xylem parenchyme is characteristic of te wJiole family, whereas METCALFE & CHALK (1965) contends that the xylem parenchyme show r s an
