Minnesota Plant Life. xv 



Fic. 49. Branch of a club-moss plant, bearing two cones; with a single 

 leaf of the cone, showing the spore case and one of the 



spores, the latter much magnified. After Atkinson 156 



Fig. 50. Flat-branched club-moss. After Britton and Brown 158 



Fig. 51. Smaller club-moss. To the left a plant with three cones, next 

 a single cone dissected to show the spore cases, next a single 

 large-spore-case with four spores revealed, and on the right 

 a small-spore-case with the small spores sifting oat. After 



Atkinson i59 



Fig. 52. Adder's-tongue fern. After E. N. Williams, in Mcchans 



Monthly 162 



Fig. 53. Virginia grape-fern. After Britton and Brown 163 



Fig. 54. A quillwort plant. After Atkinson 164 



Fig. 55. Clayton's, or interrupted fern. After Britton and Brown 164 



Fig. 56. Bed of ferns. Sensitive fern in middle of foreground. After 



photograph by Williams 165 



Fig. 57. Cliff-brake. After Britton and Brown 166 



Fig. 58. The interrupted fern (in background) and shield-ferns 'in fore- 

 ground). After photograph by Williams 167 



Fig. 59. Four-leaved water-fern. After Britton and Brown 168 



Fig. 60. A sexual fern-plant somewhat magnified. Its natural size is 

 about a quarter of an inch across. The round bodies are 

 spermaries, the chimney-shaped ones are egg-organs, seen 



from below. After Atkinson 168 



Fig. 61. A fern-plant embryo imbedded in the enlarged egg-organ, 

 where it arose by segmentation of an egg. S, tip of rudi- 

 mentary stem; L, tip of first leaf; R, tip of primitive rootlet; 



F. nursing foot. Much magnified. After Atkinson 169 



Fig. 62. Portion of maiden-hair fern leaf, showing marginal pockets, 

 which serve to protect the clusters of spore-cases under each 

 flap. After Atkinson 170- 



