Lamium orientale

Atasagun, Bayram, Aksoy, Ahmet & Martin, Esra, 2015, Contribution to the systematic knowledge of Lamium multifidum and L. orientale (Lamiaceae), Phytotaxa 203 (2), pp. 147-158 : 151-152

Lamium orientale

Root:—The cross section of the root has at its outermost section a 3–4 cell thick periderm layer consisting of rectangular cells. Certain parts of the periderm have been disrupted. Under the periderm is a 6–9 cell thick parenchymatous cortex consisting of oval or rectangular cells. In the layer that follows the cortex is the vascular bundle. Immediately under the phloem, it is possible to distinguish a cambium consisting of several layers of cells. The xylem tissue under the cambium has numerous trachea and tracheids. The xylem rays consist of 1–4 layers of rectangular cells ( Fig. 4A ).

Stem:—The epidermis forms the outermost section, and consists of several layers of rectangular cells. There are trichomes scattered on the epidermis. The collenchyma consists of 8–10 layers of cells, and is located only in the corner sections. The cortex consists of 2–6 layers of oval or rectangular shaped parenchymatous cells. Cortex cells, which are closer to the epidermis, are smaller than those closer to the vascular bundles. Inside the vascular bundles, the xylem is located inwards, while the phloem is located outwards. There is also a cambium between the xylem and phloem, which is difficult to distinguish. The pith region underneath the vascular bundles consists of large diameter cells with round or polygonal shapes ( Fig. 4B ).

Leaf:—Both the upper and lower sides of the leaf consist of a single layer of regular and rectangular cells with no spaces between them. Cells in the upper epidermis are larger than those in the lower epidermis. There are hairs on both the upper and lower epidermis. The leaf type is bifacial. Under the upper epidermis is a palisade parenchyma consisting of regularly arranged cylindrical cells. Underneath of this palisade parenchyma is a spongy parenchyma consisting of irregularly arranged cells with numerous spaces between them ( Fig. 4C ).

In the center of the cross section taken from the median vein, there is a vascular bundle consisting of the phloem and xylem. The vascular bundles are surrounded by a single layer of sclerenchymatic cells. The region between the sclerenchymatic cells and the epidermis is occupied with parenchymatous cells ( Fig. 4D ).

Figures

FIGURE 4. Cross section of Lamium orientale A. Root. B. Stem. C–D. Leaf (p: periderm, c:cortex, ca: cambium, x: xylem, t: trachea, pi; pith, pr: pith ray, co: collenchyma, ph: phloem, ad: adaxial surface, ab: abaxial surface, ue: upper epidermis, le: lower epidermis, p: parenchyma, pp: palisade parenchyma, sp: spongy parenchyma, vb: vascular bundle, h: hair).