Rosaceæ. 93 



formed, which usually bears 4 — 6 scale-leaves in two rows: it 

 probably does not elongate until the end of summer. The 

 specimens figured in Fig. 35, B had been growing in a sphag- 

 num-bog, and the height of the latter has compelled the 

 young shoot to elongate to an unusual extent. The propa- 

 gative shoots pass through the winter with their apices at 

 the surface of the ground. Next year the assimilatory shoot 

 is formed, which also has elongated internodes; it is termi- 

 nated by the solitary flower or by the dead apex of the stem 

 which is hidden in the upper leaf-sheath. The foliage-leaves, 

 which are usually few in number, are two-rowed as are the 

 scale-leaves. Often, the foliage-leaves, especially the upper, 

 also subtend solitary flowers, or slender vegetative shoots 

 occur. The propagating shoots, two or more of which may 

 occur, are as a rule subtended by the lower scale-leaves; buds 

 subtended by other scale-leaves remain dormant or the upper 

 ones may develop proleptically during the same year as the 

 parent-shoot, which results in the individuals becoming fairly 

 rich in shoots. — According to Sylvéx Rub. arcticus appears 

 to pass through the winter in a partially green condition. 



Anatomy. The horizontal shoot-bearing roots are 

 protected by a cork-periderm of about 6 layers without inter- 

 cellular spaces. They are in connection with the shoot-bases, 

 lh»' plant's reservoir of food-material, and in them the several- 

 layered pericycle and the one-layered, but several cells high, 

 medullary rays in the secondary wood become filled with 

 starch. From the rhizome adventitious roots arise. The 

 absorbent roots are of the nature of mycorrhiza and have 

 a peculiar structure. The epidermis consists of low cells 

 with very strong outer walls (4« thick). The structure of 

 the inner layer of the cortex, which is about 4 layers thick, 

 is as in Rub. saxatilis, but the thickenings of the walls are 

 less and there is an unthickened part on the outer tangential 

 wall. The rather thick endodermis, the thickenings of the 



