ИСТИНА

Atraphaxis, Bactria, and Persepolium are close related in phylogenetic reconstructions based on molecular and morphological data. Atraphaxis is sister to Persepolium, their common clade is sister to Bactria, what let to trace evolution of their morphological features. Bactria combines two rare endemic shrubs from Pamir and Tian-Shan. They have terminal frondulose thyrses of 5-10 spaced cymes of 2-3 flowers. The campanulate perianth has five equal segments covered adaxially and abaxially with elongate-rectangular sinuate epidermal cells with random cuticular striation. Eight filaments are deeply inserted in receptacle lined with nectar-secreating tissue. These characteristics rather indicate entomophily. Persepolium combines five dwarf caespitose undershrubs or shrubs endemic for SW Iran. They have terminal frondose or frondulose thyrses of 10-20 well spaced cymes of 2-3 flowers, urceolate or campanulate perianth divided in 5 equal coriaceous segments densely velutino puberulent. The outer perianth surface is covered with elongate-rectangular epidermal cells forming short trichomes, alternating with stomata. Nectar-secreating tissue lines the receptacle and the bases of filaments inserted deeply in receptacle. These features are usual for self-pollinators. Atraphaxis numbered ca 35 shrubs or undershrubs is distributed from SE Europe to South Siberia and China. Atraphaxis has compact bracteose thyrses of 6-20 congested cymes of flowers and diverse perianth which is 1) campanulate with 5 equal segments and short funnel-form tube, 2) specialized with long filiform tube, two or three accrescent inner segments and two outer segment; 3) specialized with short filiform tube, three inner segments spherically surrounding the ovary and two reflected ones. Due to the campanulate perianth with five equal segments and short tube is shared by some Atraphaxis species, Bactria and Persepolium, it can be treated as initial to the other types of perianths in Atraphaxis. Dimeric flowers can be treated as the last novelty appeared in A. section Atraphaxis which formed distal subclade in phylogenetic reconstructions. Showy petaloid perianth of Atraphaxis has white or brightly colored segments covered outside and inside with rectangular-elongated cells sinuate in outline, with random cuticular striation. The expanded part of tube is covered with polygonal cells with random cuticular striation. The filiform basal part joint to long pedicel serves for better exhibition of the perianth in compact thyrse. Nectar-secreating tissue lines short receptacle and the inner surface of the filaments, which are inserted at the edge of receptacle to ease exposure of pollen. This morphological complex was formed in Atraphaxis as an adaptation to entomophyly. Pollen grains in all the taxa are prolate to subprolate, spheroidal to oblong-spheroidal, tricolporate, elliptical in equatorial view, trilobed-circular in polar view. Bactria has microreticulato-foveolate or foveolate-perforate sporoderm surface. Persepolium has foveolate, foveolato-perforate to microreticulato-foveolate sporoderm surface, excepting P. dumosum which has striato-perforate sporoderm surface. Atraphaxis has striato-perforate sporoderm surface originated from reticulate-perforate surface present in A. toktogulica by arranging of lumina in rows, rising of lateral edges of lumina, and emerging of grooves with rows of perforations. Striato-perforate sporoderm surface possibly reduces the weight of pollen and facilitates transfer by pollinators.