POLYPODIUM. 47 



balls ; and in the next, but while the pin- 

 nules are yet rolled up, often resembles a 

 single or double budded cross. Sori mar- 

 ginal, white, afterwards black. April. 

 Deciduous. In limestone districts. Suc- 

 ceeds well. Very hardy, bearing drought 

 and exposure, and throwing out fresh and 

 fresh fronds continually. Ornamental. 

 DIIYOPTERIS. (Oak or Tender Three- 

 branched Polypody.} Fig. 43. From 4 to 

 10 inches. Growing in close masses. 

 Something of the character of the pre- 

 ceding in its threefold arrangement, but 

 otherwise impossible to be mistaken for it. 

 Light vivid green. Frond shorter, ob- 

 tusely-triangular, drooping, convex. Stem 

 slighter. Pinnae opposite, fewer, wider, 

 shorter, and more abruptly tapering, in- 

 complete above. Pinnules and pinnulets 

 broader, smooth, and thinner in substance, 

 and not glandulous nor scented. The 

 whole a much more succulent and tender 

 plant. Sori marginal. April. Deciduous. 

 Chiefly in the North. Not so hardy, pre- 

 ferring shade and moisture. Both are 

 ornamental and singular in their full top 

 springing from so slender a stem, as though 

 they were diminutive trees. 



The drawback to the genus is, that the roots creep- 



