Anatomical and palynological comparison of three endemic species of Teucrium sect. Teucrium of Turkey Author Atasagun, Bayram text Phytotaxa 2022 2022-09-29 566 3 251 267 http://dx.doi.org/10.11646/phytotaxa.566.3.1 journal article 156938 10.11646/phytotaxa.566.3.1 becc08f3-9c7d-4e55-82ef-287bdc47d606 1179-3163 7137774 Teucrium pestalozzae Boissier (1853: 90) Stem: In the cross section of the stem, there is a single layered epidermis composed of rectangular cells in the outermost part. The epidermis cells are 6.98–26.56 × 4.65–14.06 μm in size. There is a thin cuticle layer on the epidermis. The cuticle thickness is between 2.34–7.81 μm. Glandular and non-glandular trichomes are localized on the epidermis. The cortex layer, which consists of 6–7 rows of oval parenchymatic cells, is located under the epidermis layer. Cortex cells are 9.38–29.68 × 5.47–25.00 μm in size. There are starch grains inside the parenchyma cells. The endodermis is composed of a single layer, quadrangular, flat and oval cells. The endodermis cells are 8.59–19.53 × 6.20–17.05 μm in size. Phloem and xylem elements can be distinguished in vascular tissue and xylem elements are well-developed. Tracheal cells are 2.33–20.93 μm in diameter. Between the phloem and the xylem, there are 1–2 rows of cambium. The pith rays are composed of a single row of cells. In the middle, there is a pith region composed of circular parenchymatic cells. The thickness of the parenchyma cells is between 4.69–41.86 μm ( Fig. 2B ). Leaf: The outermost protective tissue is the epidermis layer, which consists of a single row of rectangular cells. The epidermis cells are surrounded by a thick cuticle layer. Lower epidermis cells are smaller than upper epidermis cells. The lower epidermis cells are 7.04–24.64 × 4.93–15.49 μm and the upper epidermis cells are 13.38–64.78 × 10.56–39.43 μm in size. There are glandular and non-glandular trichomes on both epidermis. However, this number is higher in the lower epidermis. Leaves are bifacial. Under the upper epidermis, there are 2–3 rows of palisade parenchyma composed of cylindrical cells. The palisade parenchyma cells are 4.51–11.83 × 20.84–42.81 μm in size. Palisade parenchyma covers 43–77 % of the mesophyll layer. Under the palisade parenchyma, there are 2–3 rows of sponge parenchyma with more intercellular spaces. Sponge parenchyma cells are 8.45–22.53 μm in diameter. The mesophyll tissue is 105.6–209.10 µm thick. Both parenchyma tissues contain starch grains ( Fig. 2C ). FIGURE 2. Teucrium pestalozzae 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). Leaves are hypostomatic as stomata are observed only on the lower surface. The stomatal index on the lower leaf surface is 23.69. The walls of the epidermis cells are undulate. Midrib: The midrib shape is orbicular. There is collenchyma under both epidermis in the middle vein region. While the collenchyma layer under the upper epidermis has 2–3 rows, the collenchyma layer under the lower epidermis has 3–4 rows. The collenchyma cells are 8.45–23.94 × 6.34–16.41 μm in size. The vascular bundles are of collateral type and are surrounded by a single row of regularly arranged bundle sheaths. The bundle sheath cells are 6.44–32.19 × 7.24–24.14 μm in size. The xylem facing the upper epidermis and the phloem facing the lower epidermis are found in the vascular bundle. Under the phloem, there is a sclerenchymatic tissue ( Fig. 2D ). Pollen: Pollen grains of Teucrium pestalozzae are radially symmetrical, isopolar and tricolpate. Pollen shape is prolate, medium sized, polar axis is 28.95±2.28 μm and equatorial axis is 20.01±1.69 μm long. AMB is semi-circular, ornamentation is verrucate. Colpus elongated 19.48±2.21 μm. Exine is 1.94±0.43 μm and intine is 1.14±0.3 μm long ( Fig. 5 , Table 3 ).