Schrader : observations on alaria nana. 163 



Collected at Postelsia point, Minnesota Seaside Station, July- 

 August, 1902. 



Summary. 



1. Alaria nana is one of the smallest Alarias known, mature 

 plants seldom being longer than 50-70 cm. 



2. At the Minnesota Seaside Station it is a surge plant, belong- 

 ing in the same group as Lessonia littoralis and Postelsia palm ce.- 



f or mis. 



3. The holdfast does not show growth rings. 



4. The growth of the stipe in thickness is radial, and this 

 difference in growth and shape of the outer and inner cortex, 

 caused by a cambial layer, sometimes gives a ringed appear- 

 ance to the stipe. Mucilage ducts are not present; crypto- 

 stomata were found neither in stipe nor in lamina. 



5. The sori occur in large patches on both sides of gonidio- 

 phylls produced laterally on the stipe. The paraphyses have 

 large thick mucilaginous caps as in Lessonia and Pterygophora. 



Explanation of Figures. 



All drawings, except diagrams of sections were made with the Abbe 

 camera lucida, under an enlargement of X 530, unless otherwise stated. 



Plate XXIII. 



Postelsia Point at Minnesota Seaside Station — showing Postels ia 

 palmcej ~orm is, Alaria and other surf plants. Photographed by C. J. 

 Hibbard. 



Plate XXIV. 

 Photograph of two mature and fair sized plants, and of ' three 

 small plantlets, one third natural size. Photographed by C. J. Hib- 

 bard. 



Plates XXV and XXVI. 



1-10. Various young stages of Alaria drawn natural size; Figs. 4 

 and 5 showing very young gonidiophylls ; Fig. 9 the gonidiophylls are 

 quite mature. 



11. Diagrams of sections of stipe, a, transverse section showing 

 different tissue areas; 5, longitudinal section at base showing origin 

 of secondary hapteres in the cortex and two burrows in the stipe, 

 made by small crustaceans ; <?, epidermis ; c, cortex ; p, pith ; .v, bur- 

 row of crustacean; /i, hapteres. 



