Teucrium semrae Aksoy et al. (2020: 326)

Atasagun, Bayram, 2022, Anatomical and palynological comparison of three endemic species of Teucrium sect. Teucrium of Turkey, Phytotaxa 566 (3), pp. 251-267 : 256-257

Teucrium semrae Aksoy et al. (2020: 326)

Stem: In the cross section of the stem, there is a thick cuticle layer in the outermost part. Beneath, there is an epidermis layer, which consists of single-row, rectangular and oval cells as a protective tissue. The epidermis cells are 6.20–24.03 × 3.10–11.62 μm in size. There are non-glandular and glandular trichomes on the epidermis. Just under the epidermis, there is a 6–8 layered cortex layer that occupies a narrow space. The cortex parenchyma cells are 6.98–31.00 × 6.20– 36.43 μm in size. The endodermis layer is composed of a single row of rectangular cells with a size of 10.07–35.65 × 5.43–16.27 μm. Between the phloem and the xylem, there is the cambium made up of several rows of flat cells. In the xylem, there are localized sclerenchyma elements between the trachea and the tracheids. Tracheal cells are 2.33–19.37 μm in diameter. The pith rays are in a single row and the innermost pith is composed of parenchymatic cells. The diameter of the parenchyma cells in the pith region is between 6.98–30.23 μm ( Fig. 3B ).

Leaf: In the cross section of the leaf; there is an epidermis layer consisting of a single row, regularly arranged and rectangular cells on the lower and upper parts. Above the epidermis layer, there is the cuticle layer. Upper epidermis cells are considerably larger than the lower epidermis cells. The upper epidermis cells are 7.75–39.71 × 9.15–22.69 μm and the lower epidermis cells are 3.52–13.38 × 3.52–10.56 μm in size. Trichomes are found on the leaf surface and lower part. The leaf is bifacial (dorsiventral) and under the upper epidermis, there is a double-rowed palisade parenchyma containing abundant chloroplasts. The palisade parenchyma cells are 4.69–12.20 × 14.55–29.57 μm in size. Under the palisade parenchyma, there is a 2-row sponge parenchyma with wide spaces. Sponge parenchyma cells are 9.22–27.65 μm in diameter. Palisade parenchyma covers 53.4–66.7% of mesophyll tissue. The mesophyll tissue is 83.09–265.90 µm thick. Starch grains are present in both parenchyma tissues ( Fig. 3C ).

Leaves are hypostomatic as stomata are observed only on the lower surface. The stomatal index on the lower leaf surface is 21.50. The walls of the epidermis cells are undulate.

Midrib: The midrib shape is rectangular. The vascular bundle in the midrib is larger than the others. There are crystals in the tissue under the upper epidermis. Collenchyma under both epidermis layers has 2–3 rows. The collenchyma cells are 7.04–23.23 × 6.34–21.12 μm in size. There is a bundle sheath consisting of a single row of parenchymatic cells localized around the vascular bundle. The bundle sheath cells are 4.23–35.21 × 3.52–15.49 μm in size. Vascular bundle is collateral type, xylem and phloem are clearly distinguished. The xylem is located on the adaxial side and the phloem is located on the abaxial side ( Fig. 3D ).

Pollen: Pollen grains of Teucrium semrae are radially symmetrical, isopolar and tricolpate. Pollen shape is prolate, medium sized, polar axis is 40.95±3.47 μm and equatorial axis is 24.49±2.69 μm long. AMB is semi-circular, ornamentation is microverrucate. Colpus elongated 28.08±2.67 μm. Exine is 1.85±0.36 μm and intine is 1.09±0.18 μm long (Fig. 6, Table 3 ).

Figures

FIGURE 3. Teucrium semrae A. Habit, B. Stem cross section, C. Leaf cross section, D. Midrib cross section (pd: periderm, co: collenchyma, sc: sclerenchyma ca: cambium, ph: phloem, xls: xylem, tr: trachea, pt: pith, ep: epidermis, tc: trichome, cu: cuticle, ue: upper epidermis, le: lower epidermis, pp: palisade parenchyma, sp: spongy parenchyma, p: parenchyma, bs: bundle sheath).