351 



Altai, Arctic America with the Archipelago, and the Rocky 

 Mountains (Simmons, 1906). 



Anatomy. The adventitious roots of the first 

 order are triarch-tetrarch, and those ot the second order 

 diarch. Both the epidermis and the exodermis are suberized; 

 in several specimens the former is found to have collapsed, 

 the latter has undulating radial walls. The two outer layers 

 of the cortex within the exodermis are slightly collenchyma- 

 tously thickened ; the rest of the cortex has large intercellular 

 spaces and, in older roots, large lysigenous lacunae. The cells 

 of the endodermis had become slightly thickened and suberized, 

 and several had divided tangentially. This species, as is also 

 the case in the other species of Ranunculus which have been 

 investigated, has a large pentagonal tube in the outer part 

 of the sieve-tissue wedged in between adjacent cells of the 

 pericycle. Mycorrhizas have been found, both in the principal 

 form and in var. Wilanderi] it was always only roots of the 

 second order that contained hyphae which were often rolled 

 together into balls. 



The structure of the rhizom. e is similar on the whole 

 to that of the other species with erect axes which have been 

 investigated (Fig. 10, Ä). Stereom is absent. The epidermis 

 and the outermost layer of the cortex are often suberized and 

 collapsed ; the cortex is lysigenously lacunose. 



The cuticle upon that part of the stem which has elongated 

 internodes, is striped. The tangential walls of the epidermis 

 are somewhat thickened, the radial walls are furnished with 

 pores; the epidermis contains chlorophyll. Upon the upper 

 part of the stem the slomata are fairly numerous and they 

 project slightly. Large intercellular spaces occur in the cortex (the 

 sub-epidermal layer not included), but no lacunae. The stereom, 

 as usual, is most strongly developed in the fruit-bearing axis. 

 The fibrous tissue outside the leptome may reach a thickness 

 of seven layers and the lignified cells of the medullary rays 



