Comparative study of the vegetative and flowering axes ofLeonurus sibiricus L.
In the study of the anatomy of the vegetative and flowering regions ofLeonurus, three important features have been observed:
The unbranched condition of the flowering axis with extreme reduction of leaf lamina;
The greater activity of cambium in vegetative than in the flowering region which appears to be due to the difference of photosynthetic activities in the two regions of the plant; and
The endodermis which is well developed in the flowering region is only a ‘starch sheath’ in the vegetative region. The change from starch sheath to endodermis appears to be concerned with the xeromorphy of the flowering region indicated by the extreme reduction of the leaf lamina in this region.