Fig 1.
Heteromorphic leaves of one Populus euphratica tree from bottom to top of the crown (Pe1–Pe12) at the P. euphratica Reserve in the Ejina Oasis.
Pe1, linear leaf; Pe2, Pe3, lanceolate leaf; Pe4, ovate leaf; Pe5, Pe6, dentate ovate leaf; Pe7, Pe8, dentate rhombic leaf; Pe9, Pe10, dentate broad-ovate leaf; Pe11, Pe12, dentate fan-shaped leaf. From Pe5 to Pe12, the level of dentate degree increased.
Table 1.
The main characteristics related to stress resistance of the Populus euphratica leaves.
Fig 2.
Cross-section anatomical characteristics of Populus euphratica heteromorphic leaves from Pe1 to Pe12.
The images are shown in ×40 magnification, scale bars = 10 μm. U-ep, up-epidermis; D-ep, down- epidermis; Ec, epidermal cells; Pal, palisade tissue; BSC, bundle sheath cells; VB, vascular bundle; Mu, mucilage cells.
Fig 3.
Crystal idioblasts exhibited in the cross-section of Populus euphratica heteromorphic leaves.
The images show that crystals appear in all parts of the leaf structure, including (A) palisade tissue, (B) epidermal cells, and (C) Phloem of vascular bundles. Scale bars: A, B = 50 μm, C = 20 μm. Cr, crystal cells.
Table 2.
Statistical data on epidermal micromorphological and mesophyll anatomical characters of the Populus euphratica heteromorphic leaves.
Fig 4.
Morphological characters of epicuticular wax crystals on the adaxial epidermis of Populus euphratica heteromorphic leaves from Pe1 to Pe12.
Scale bars: Pe1–Pe12 = 5 μm.
Fig 5.
Trichomes on the adaxial epidermis of Populus euphratica heteromorphic leaves from Pe1 to Pe12.
Scale bars: Pe1–Pe7 = 50 μm, Pe8–Pe12 = 100 μm. H, leaf hairs.
Fig 6.
Morphological characteristics of stomata on the epidermis of Populus euphratica heteromorphic leaves from Pe1 to Pe12.
Scale bars: Pe1–Pe12 = 5 μm.
Fig 7.
Chloroplast ultrastructural characters in the mesophyll cells of P. euphratica heteromorphic leaves from Pe1 to Pe12.
The images are shown in ×30,000 magnification, scale bars = 1 nm. Cp, chloroplast; Sg, starch grain.
Fig 8.
HCA dendrogram of Populus euphratica heteromorphic leaves.
Table 3.
Ranking of drought resistance in the development of Populus euphratica heteromorphic leaves based on subordinate function values.