76 
HANDY BOOK OP 
Some of the fronds are barren, others fertile. The former 
rising from the bog in May, the latter in July they both 
disappear with the first frosts of winter. The frond is lan- 
ceolate and pinnate ; the lowermost pinnae are shorter than, 
the third and fourth pairs ; they are attached by their 
VEINS AND THEC.E. 
stalk only ; about one-third of the rachis is without pinnae ; 
the pinnae are pinnatind, the pinnulse rounded, and always 
entire ; the whole plant is erect, very slender, delicate, and 
fragile ; it is of a pale green colour ; in size varying con- 
siderably, in some instances even to four times the usual 
dimensions. The fertile fronds are uniformly larger and 
of stronger growth than the barren. 
The lateral veins are alternate ; they are forked almost 
immediately on leaving the mid-vein, and each proceeds to 
the margin of the pinnula, bearing a circular mass of thecae 
almost directly after the fork. Each mass of seeds has, in 
an early state of the plant, a small subreniform indusium 
attached on one side to the vein, at the point to which the 
stalks of the thecoe arc affixed. 
