56 Knud Jessen. 



stronger than those in the roots of the first order. The lateral 

 roots have endotrophic mychorrhiza. The older roots are 

 surrounded by a periderm which is formed in the outermost 

 layer of the pericycle. The phelloid-cells occur in a few 

 layers, and each series is separated by a layer of cork. Large 

 intercellular spaces occur between the phelloid-cells them- 

 selves and between the latter and the next inner layer of cork. 



In the rhizome there is formed during the first period of 

 vegetation a complete ring of cambium which, however, does 

 not produce a particularly large amount of secondary wood 

 during the first year. With increasing age the latter reaches 

 a considerable thickness and the continuous woody portion 

 is very large; the annual rings in older rhizomes are not dis- 

 tinct. When older the rhizome becomes highly hyponastic. 

 An endodermis is present. Periderm is formed during the 

 first or second period of vegetation, after which the primary 

 bark with epidermis dies and falls off. In the periderm one 

 layer of cork alternates with about three layers of phelloid- 

 cells. Specimens investigated from the Botanic Garden in 

 Copenhagen had a smaller amount of cork in the periderm 

 than the specimens from the other localities. Large inter- 

 cellular spaces occur which are distributed as in the root. 

 The outer, dead portion of the periderm persists as a very 

 thick protective layer. Normally, no bast is produced in 

 the rhizome, only in very vigorous specimens from the Bota- 

 nic Garden in Copenhagen did I observe scattered groups of 

 bast-cells. The pith is large and lives for a long time; it is, 

 together with the periderm and the medullary rays, the chief 

 depository of food-material. The starch collected during 

 summer disappears, at any rate partially, during winter and 

 is replaced by fat (Bot. Gard, in Copenhagen, January). 



Hollstein has described the floral stem from ma- 

 terial from the Dauphiné Alps. There occurred in the 

 stems from these regions considerably more stereom than 



