l6 OUR NATIVE FERNS AND THEIR ALLIES. 



ing a single sorus. The veins extend nearly at right angles to 

 the midvein, are free, and usually forked. 



46. Camptosorus. — The walking-leaf has oblong or linear 

 indusiate sori, which are irregularly scattered and borne parti)' 

 on veins parallel to the midvein, and partly on those that are 

 oblique. Those near the midvein are single, those toward the 

 margin are often approxiijiate in pairs and often form crooked 

 lines. The veins are everywhere copiously reticulated. 



47. Phegopteris. — In this genus the sori are round and 

 naked as in Polypodium, with which this genus was formerly 

 united. The sporangia spring from the back of the veins in- 

 stead of the apex, as in the latter genus, and the veins are free 

 except in the § Goniopteris, in which they are more or less 

 united. 



48. Dryopteris is largely represented in our limits by two 

 well marked groups which it is best now to regard as distinct 



^. genera, and two others with characters scarcely 



• less distinct, containing each a single species. 



I ' j| In all the sori are roundish, and borne on the 



*■ -. 1 back of the veins or rarely at their apex. In 



« - , f covers the sorus and is attached by its margin, 



\"«-/a. ^ I but later bursts away at the margin but remains 

 ly ly. , attached at the sinus. In some species in this 

 "^^^^p section the indusium becomes shrivelled before 

 Fic. 8. — Under the fruit matures, and in this condition might 

 mtn°of L")!,/.'r^; be mistaken for a non-indusiate species (Fig. 8). 



Jilix-ttias, with In polystichum the indusium is orbicular 

 eight son. r, the , 



indusium. Magni- and peltate, being fixed by the centre ; the veins 



fied. (After Sachs.) , ■!.-»? 



are free, as m § Nephrodium. 

 In Phanerophlebia the indusium is the same as in POLY- 

 STICHUM, but the veins tend to unite near the margin, while in 

 Tectaria the veins anastomose copiously. 



49. Nephrolepis has roundish sori borne at the apex of 

 the upper branch of a free vein, near the margin of the frond. 

 The indusia are usually reniform, fixed by the sinus or base, and 

 open toward the margins of the pinnae. 



50. Filix. — The small bladder-ferns take their popular 

 name from the delicate, hood-like indusium which is attached 



(' f ^^ I Dryopteris the indusium is cordato-reniform 

 '( ^ or orbicular with a narrow sinus. This at first 



