STUDY ON DEVELOPMENTAL MORPHOLOGY OF PEDICULARIS STRIATA PALL.
细叶马先蒿根系发育形态学研究

Pedicularis striata Pall. is a perennial herb in Scrophulariaceae. The yearly growth cycle shorten obviously. During nutritive growth and blooming stages all the thick main root and its fine banches exist. But the latter is almost withering and fall off completely in fruit stage. It is very rare that the survive root system is milk white. The primary root is covered with root hairs densely. The primary xylem is diarch. There is only vascular cambium but no cork cambium in lateral meristem. The epidermis cell divides anticlinally within mother cell and elongates periclinally in cross section. It can be seen that the shape of the whole epidermis cell is irregular square when it is dissociated. The root perimeter can be prolonged by this special growth type to adapt root thickening. The exodermis cell takes the place of epidermis cell with the same way when epidermis fall off. To accompany fine branches withering,a lot of winter root primodia arise at the end of growing period. According to its yearly developmental rhythm,the root system is partial renewal type and withering not only absorb roots but also fine branches.