284 KANSAS UNIVERSITY SCIENCE BULLETIN. 



In young stems the vascular system is separated from the 

 hard bast by a region of pericycle ground parenchyma con- 

 taining chloroplasts, this part of the pericycle, in company 

 with certain of the medullary ray cells and those of the pith, 

 functioning in photosynthesis. 



Bast Fibers. 



Just without the thin-walled parenchyma of the pericycle lies 

 the bast tissue, varying in extent from isolated bundles to a 

 complete rigid cylinder around the stem. On comparing cross 

 sections taken at different heights (compare figs. 1, 2, and 3), 

 the bast appears to form a sort of anastomosing structure, 

 dividing in places to allow for conduction of materials between 

 the pericycle and cortex. The bast fibers are sparingly pitted, 

 and have the usual long, tapering form. 



Endodermis. 



There is a very distinct endodermal tissue or starch sheath 

 lying just without the bast ring, this being a type character of 

 the Compositse (Solereder), heavily loaded with large starch 

 grains, these forming a dark purple ring around the stem, 

 when it is sectioned and treated with Iodine. 



Lying in this endodermal region are found secreting spaces, 

 occurring usually in pairs at the angle where the bast ring 

 alternately bulges out and becomes depressed, there often 

 being twenty of these spaces seen in cross section. These 

 endodermal secreting canals (fig. 22), forming the type char- 

 acteristic of the order Compositse (Solereder, 1908), are in 

 Geertneria not evident much beyond 3 cm. back from the 

 growing apex. 



Cortex. 



The cortex is made up of cortex parenchyma and collen- 

 chymatous tissue. The thin-walled parenchyma of the cortex 

 averages six cells deep, and is made up of ovoid or cuboidal 

 cells, with cellulose walls. There are many, though incon- 

 spicuous, intercellular spaces in this region, and, until the tis- 

 sue becomes transformed into cork, which occurs later by the 

 suberization of its walls, it has an active part in food manu- 

 facture. 



There is found in this region no definite cork cambium, but, 

 as stated above, the walls of the cortex cells finally become 

 suberized. Solereder (1908, vol. I, p. 493) reports the absence 

 in a somewhat similar case of a distinct cork cambium in 



