( 3i ) 
GROUP I; GENUS X; SPECIES VIII. 
LASTREA THELYPTERIS. (Marsh Fern.) 
Plate XIII. 
I' Ronds. Lanceolate, pinnate. The fertile taller than 
the barren fronds. Pinnae linear-lanceolate, 
pinnatifid. Lobes rounded and smooth on 
the margin, those of the fertile fronds being 
revolute at the edge, which gives them a 
contracted appearance. Stipes frequently 
longer than the leafy part of the frond. 
Growth. Nearly erect. Fronds springing from a 
thin, black, creeping rhizoma. 
Height. Barren fronds one foot; fertile fronds from 
two to two and a half feet. 
Colour. Pale green. 
Habitats. Wet boggy heaths or marshes. Not un¬ 
common in England. 
(See also page 54.) 
