Ontogeny of trichomes in taxa of genus Plantago L. subgenus Plantago

The development of three types of headed hairs has been studied: 1) hairs with a unicellular stalk and a head divided vertically into two cells, 2) bottle-like hairs, 3) morel-like and two types of headless hairs: a) with a characteristic 2-3-celled base, b) without the characteristic base in six representatives belonging to 4 sections of the genus Plantago L. The bottle-like and the morel-like hairs may have originated from the hairs with a unicellular stalk and a head divided vertically into two cells. The Plantago sections characterized by the presence of the bottle-like and morel-like hairs are probably evolutionally younger than the sections characterized by the presence of hairs with a unicellular stalk and a head divided vertically into two cells.