Anatomy of Johnsongrass

The number of vascular bundles in the rhizomes of different ecotypes of johnsongrass ( Sorghum halepense (L.) Pers.) varied from 71 to 154. The size of vascular bundles varied from 60 to 150 μ in an ecotype from California to 100 to 230 μ in an ecotype from Georgia. The size of xylem cells in these vascular bundles also varied widely, but the size of phloem cells was more constant. The number of vascular bundles in culms ranged from 43 to 123. The average number of vascular bundles in individual leaves varied from 46 to 158 for different ecotypes. The number of stomata on leaf surfaces deviated from 63 to 148/sq mm for 10 different ecotypes. An average of 95 stomata/sq mm occurred on the upper surface of johnsongrass leaves while an average of 113 stomata occurred on lower surfaces. The arrangement and size of stomata varied in different johnsongrass ecotypes.