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

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

zone divide by radial walls. Many pericambial cells are now septa Le by 2—3 radial walls. Most of the endodermal cells are by now secondary, with one radial cell wall (Pl. IV, Fig. 1). The cells of the primary cortex are easily detachable, and this intense dividing of the pericambial zone indicates the approaching decortication and periderm formation. The main developmental stages of the vascular bands of the radicula are schematically shown in Fig. 2. 2. The hypocotyl Depending principally on the development of the radicula, I found various kinds of fascicular transitions (rearrangements) from the radicula into the hypocotyl (Fig. 3). In the majority of the examined seedlings, the structure of the central cylinder in still radicular in character at the lower level of the hypocotyl, but the primary cortex already reveals a stem structure. The Caspari-punctate endoderm is concurrently also a starchy sheath (Pl. IV, Fig. 2). The primary cortex is delimited by radially elongated epidermal cells (46x18 u.) with hairs of a cystolithic content. This supraterranean shoot, with its outer appearance and green colour (chlorophyll), has a stem character. In the youngest roots I studied —in which the procambium fascicle had not yet differentiated completely and the waved cambium not closed into a ring

— the radially situated two xylem fascicles widen and turn into a tangential direction during their transition into the hypocotyl, but they remain in the cotyledonary level. The cambium closes into a ring. Both phloem fascicles bifurcate below the insertional points of the cotyledons, extending from the transversal into the Fig 2. Main developmental stages of the vascular bands of Lhe radicula in cross sections, schematically