562 MINNESOTA BOTANICAL STUDIES. 
and more robust stipe. It differs from A. angusta especially in 
the form of the sporophylls.” 
EXPLANATION OF PLATE XXXIII. 
Figure 1. Mature plant reduced %; a, 6, c, d, young plants, 
showing different stages of development. 
Figure 2. Cross section of sporophylls, x 400. 
Figure 3. Section of midrib, x 2. 
