Ontogenetic variability of morphological characters of Evernia prunastri (L.) Ach. on different species of trees in different ecological conditions

The current paper is about the morphological characters variability of the epiphytic lichen Evernia prunastri. The studies were conducted on the territory of the Mari El Republic in the flooded lime-tree forest of the Bolshaya Kokshaga river. The thalli of E. prunastri of different ontogenetic states (v₁, v₂, g₁v, g₂v, g₃v, ss) were collected on Tilia cordata, Padus avium, Quercus robur at a stem height of 0,5 to 2 m and on Abies sibirica branches at heights of 3–4 m, 5–6 m, 7–8 m. Tilia cordata is the most favorable substrate for the development of E. prunastri thalli for most of its characters. The character of the thallus development (the length of the thallus) is minimal in Padus avium. The characters of death (the number of dead branches, the length of the cortex blackening area) are maximal on Padus avium, which indicates more accelerated aging processes of the thallus in this phorophyte. The thallus of E. prunastri, which grows on the branches of Abies sibirica, has the largest lengths at heights of 3–4 and 5–6 m in comparison with the height of 7–8 m. At higher altitudes, longer soralia are formed, hence, more soredia are formed. The values of most characters of E. prunastri, which grows on the right bank of the Bolshaya Kokshaga river are bigger than on the left bank, which is due to differences in the lighting of habitats. The length of the soralia on the right bank (the best lighting) is more in Quercus robur than in Tilia cordata. The variability of morphological characters is manifested in different ways in different ontogenetic states.