402 



the rhizomes of the species with erect stems; the bundles 

 anastomose and form a more or less complete ring around the 

 pith; the latter and the cortex are less lacunose; the cells of 

 the latter are somewhat tangentially elongated and there are 

 more cortical layers than in the internodes. Roots arise from 

 the nodes. 



The flower- s talk, especially towards the time for the 

 ripening of the fruit, is rather rich in stereom (Fig. 43). It is 

 somewhat polygonal in transverse section. The cuticle is deci- 

 dedly striped, and the stomata project above the surface. The 

 cortex has large intercellular spaces. Each bundle (3 — 6) is 



surrounded by a sheath of stereom; 

 there is strong fibrous tissue out- 

 side the leptome. Between the wood 

 and tlie cambium there is a several- 

 layered mass of wood-parenchyma 

 with highly thickened Avails, and 

 between the vessels and the endo- 

 dermis there is some non-lignified 



parenchyma. The interfascicular, 

 Fig. 43. R. lapponieus. 



Portion of transverse section of pe- llgniÜCd раГСПсЬуша is 5 — 6 UiyCrS 

 duncle (Spitzbergen ;"A).ej.,Epidennis; ^j^j^j^ ^^^ j^^ ^^,,g ^^^ rather highly 



c, cortex; i, intercellular space; b, bast; ° '' 



ph, leptome; x, xyiem; p, non-lignified thickcncd. The pith iu thc peduuclc 



parenchyma ; vp, lignified parenchyma. 



is found partly broken down ; its 

 cells were slightly lignified. — The epidermal cells contain 

 chlorophyll. 



The leaf. The epidermal cells as usual, have only slightly 

 thickened outer walls. The cells contain chlorophyll. Seen 

 with the naked eye the leaf shows brown spots upon both sur- 

 faces : many of the cells of the epidermis being filled with brown 

 juice, probably tannin (it did not, however, give the reaction 

 with the iron-salts). The walls of the upper epidermis are 

 slightly undulating and stomata are almost entirely absent; the 

 walls of the lower epidermal cells are highly undulating (Fig. 



