8 Knud Jessen. 



Furthermore, a more extensive assimilation is attained by the 

 expansion of the new leaves. 



Other leaves also may subtend shoots which, however, 

 usually do not grow out until next summer, and it should be 

 mentioned that such shoots which pass their first winter in 

 bud differ in certain respects from vigorous precocious shoots; 

 the latter begin with a more-or-less elongated internode, and 

 the first leaf is a foliage-leaf, so that they can begin to assi- 

 milate immediately, while the other shoots begin with 1 — 3 

 short internodes and the first 1 — 3 leaves are scale-leaves. 



After germination — probably in the spring — Potentilla 

 palustris begins a stage of vegetative growth which lasts for 

 several years. The first year it may form a rosette, but even 

 then may also have elongated internodes (Irmisch, Sylvén, 

 Warming). 



The primary root is slender, but does not die during the 

 first year (Warming); afterwards the plant is entirely depen- 

 dent on its adventitious roots which according to Irmisch 

 arise upon the epicotyledonary axis even during the first year. 

 So far as I have observed they do not arise upon the prolep- 

 tically developed shoots until during their second summer. 

 The brown, somewhat compressed stem may attain a con- 

 siderable length: I have dug up sympodia above two metres 

 in length; they may live for at least seven years. As the 

 stem branches freely, vegetative propagation takes place abun- 

 dantly. 



The two-rowed leaves usually live for one summer only, 

 but Sylvén says that a single leaf may pass the winter in a 

 green condition. After the leaves have died the large sheaths 

 persist and those seated at the apex of the year's shoot envelop 

 the winter-bud; in the latter a few scale-leaves may also be 

 developed (see Fig. 1). 



In Denmark there is no fixed rule as to the height above 

 the surface of the bog at which the shoot-apex lives through 



