IQ09 ] STOKEY— ANATOMY OF ISOETES 335 



24. Von Mohl, H., Ueber den Bau des Stammes von Isoetes lacustris. Linnaea 



14:181. 1840. 



EXPLANATION OF PLATE? X1X-XXI 



PLATE XIX 



Figs. 1-4.— I. echinospora var. Flettii. Figs. 5-8.— I. melanopoda 

 Fig. i.— Longitudinal section of the stele of young plant cut in the plane of 



the furrow. X380. 



Fig. 2.— Longitudinal section of the stem of young plant cut in the plane of 



the furrow. X37. 



Fig. 3.— Cross-section of the stele of a young plant. X380. 

 Fig. 4— Longitudinal section of a young plant cut across the furrow. X22. 

 Fig. 5.— Cross-section of the stem of old plant in the leaf-trace region. X 6. 

 Fig. 6.— Cross-section of stem below the stele showing root bundles in the 



cortex. X6. 



Fig. 7.— Cross-section of root bundle before it has left the stem. X380. 



Fig. 8. — Cross-section of mature root. X4 8 - 



PLA te XX 



Figs. 9, 10, 12-16:— I. echinospora var. Flettii. Fig. u.—L Xuttallii 

 Fig. 9.— Cross-section of mature leaf near the middle. X37- 

 Fig. 10 —Cross-section of bundle of young leaf near the tip. X380. 

 Fig. 11. — Sieve plate from sieve tube. X810. 



Fig. 12.— Cross-section of bundle of a young leaf near the middle. X380. 

 Fig. 13.— Cross-section of bundle of mature leaf cut just above ligule. X380. 

 Fig. 14.— Cross-section of leaf trace in cortex just below base of leaf. X260. 

 Fig. 15. -Cross-section of leaf trace in cortex half-way between leaf and 



vascular axis. X380. 



Fig. 16.— Cross-section of leaf trace near the vascular axis. X380. 



Fig. i 7 .-Diagram to illustrate the relation of leaf traces to secondary wood. 



Fig. 18.— Cells of cortex with starch grains. X3 8 °- 



PLA TE XXI 



Figs. 19, 20, 22.-1. echinospora var. Flettii. Figs. 21, 24, 26,-L mehinopoda 



Fig. 2 5 .—I. Nultallii. Fig. 23.— I. Tuckermam var. lUrveyi 

 Fig. iQ.-Longitudinal section of vascular bundle of old plant cut across 

 the furrow. X22/ , ' . .. 



Fig. 2o.-Longitudinal section of vascular bundle of old plant cut m the 



Plane of the furrow. X22. , , , n 



Fig. 2i.-Tracheids from secondary xylem at different stages of develop- 

 ment. X810. 



Fig. 22.— Cross-section of vascular axis of old plant. X i75- , 

 Fig. 2 3 .-Tracheids from secondary xylem; the cell on the right is sectioned 

 obliquely. X810. . , . 



, Fig. 2 4 .-Cross-section of vascular axis through the root region; trie ion 

 a *is is in the plane of the furrow. X 22. . , 



Fig. 2 S .-Cross-section of stem from the edge of the primary xylem to the 

 c °tex, showing zonation in secondary xylem. X45°- . . 



Fig. 26.~Cross-section of the stem from the edge of the pnmary xylem to the 

 cortex. X350. 



