Priraulaceae. 213 



of palisades and an aërenchyma with an exceedingly loose 

 structure consisting of much - branched cells. Chlorophyll 

 granules are plentiful throughout the mesophyll. 



Summary. 



A. Growth forms 1 and shoot-formation. 



1. Chamaephytes: Androsaces chamaejasme. 



A sedentary chamaephyte with a very persistent main 

 root. When many leaf-rosettes are crowded together, Andro- 

 saces chamaejasme shows at times distinct transitions to the 

 cushion-plant form. The adventitious roots appear very 

 sparingly, hence vegetative propagation by root-forming 

 rosettes can scarcely be of much importance. The foliage- 

 leaves die in the autumn, except the innermost, partly 

 expanded leaves. The withered leaves form a protection 

 for the embryonic tissues of the axis, while the hair covering 

 of the young leaves is most probably useful in the same way. 

 The structure of the leaves is mesomorphic. The peduncle 

 is terminal. 



2. Hemicryptophytes: All the Primula species 

 described above, and also Dodecatheon frigidiim. 



Perennial herbs with a quickly perishing main root, 

 a vertical rhizome, and with leaves arranged in basal 

 rosettes. 



The rhizome of Dodecatheon frigidum reaches a compara- 

 tively considerable length, while the Primulae have only short 

 ones, as they perish quickly from behind. The living part 

 of the rhizome of the first four species described (viz. Pr. 

 egaliksensis, Pr. sibirica, Pr.stricta and Pr.farinosaYdir. groen- 

 landica) consists of a single year-growth only. 



^ C. Raunkiær: Planterigets Livsformer og deres Betydning for 

 Geografien. København og Kristiania, 1907. 



