PLATE XL. 



Townsendia exscapa. 



Fig. 4. Cutinized epidermis of stem, cross section. R, outer tangential 



wall; S, inner tangential wall. X 650. 

 Fig. 5. Coi'k cells, cross section, x 650. 

 Fig. 6. Collenchyma cells, cross section, x 650. 

 Fig. 7. Collenchyma cells, longitudinal section, x 650. 

 Fig. 8. Short sclerenchyma cells, cross section, x 650. 

 Fig. 9. Short sclerenchyma cells, longitudinal section. X 650. 

 Fig. 10. Cortex cells, cross section, x 650. 

 Fig. 11. Cortex cells, longitudinal section. X 650. 

 Fig. 12. Pith cells, cross section, x 650. 

 Fig. 13. Pith cells, longitudinal section. X 650. 

 Fig. 14. Small portion of xylem, cross section, showing: a, tracheids; 



b, wood parenchyma cells, x 650. 

 Fig. 15. Tracheids, as seen in a longitudinal section, when isolated from 



the wood parenchyma cells by means of chromic acid. X 650. 



