CHAPTER XII 



SILVERY SPLEENWORT 



Athyrium thelypteroides. 



Rootstock creeping, forking, brown, green at tips, bearing 

 delicate, pale-brown, lanceolate or ovate-lanceolate or ovate- 

 deltoid, acuminate, slightly toothed or ciliate scales: roots 

 brown, coarse, copiously branching, springing from rootstock 

 and junctures of petiole and rootstock. 



Leaves twenty to forty-seven inches long, five to twelve inches 

 broad, sensitive to frost. 



Petioles eight to twelve inches long, shorter than blades; at 

 base dark-brown or at first partly green, turgid-compressed, 

 angled laterally and toothed along angles; above greenish- 

 straw-colored or straw-colored or brownish when dried, furrowed 

 on face; somewhat scaly and pubescent: scales pale-brown, 

 broadly ovate to lanceolate to linear, acuminate, entire, the 

 linear often, at least the upper, articulated at apex: hairs articu- 

 lated, marked at joints and sometimes lengthwise in brown or 

 golden-brown: fibrovascular bundles two, strap-shaped, uniting 

 below blade into one somewhat U-shaped in section. 



Blades lanceolate or ovate-lanceolate, gradually or abruptly 

 narrowed toward apex, somewhat narrowed at base, pinnate, 

 pinnatifid toward apex: apex acuminate, undulate to serrulate 



