194 KANSAS UNIVERSITY SCIENCE BULLETIN. 



the leaves.) The number of the stomata in the stem averages 

 67 per sq. mm., the pores being somewhat less in number; but 

 the stomata have subsidiary cells parallel to the pores of the 

 stoma, which is another special characteristic of the family, 

 as given by Solereder (figs. 17 and 23). The cell walls of the 

 very young stems are composed of cellulose, while in the older 

 stems all of the tissue exterior to the endodermis has become 

 suberized, thus forming cork. In the old stems no remains of 

 the epidermis appear. It may be that the cork has been formed 

 by the cork cambium, though no definite layer is found 

 (fig. 15). It would seem from the location of the cork that if 

 there were a cambium layer it has arisen from the endodermis. 



THE LEAF. 



The leaf is oblong, elliptical in form, tapering to a flat base 

 (fig. 25). It is from 8 mm. to 1 cm. long, about 3 mm. wide, 

 and about .13 mm. thick. 



It is covered with hair on both upper and lower surfaces. 

 These hairs are placed upon the leaf so as to run longitudinally 

 with the leaf (fig. 26). In length they average about .9 mm. 

 and have a diameter of about .025 mm. They taper to a point 

 at both ends, and their surface is covered with papilla-like pro- 

 jections (fig. 29). These hairs are fi*ee at both ends and are 

 fastened to the leaf by a stalk-like projection which fits into 

 an opening of the epidermis. This opening resembles a pore 

 (figs. 28 and 29). This kind of a hair is an anatomical 

 characteristic of the family Malpighiaceae according to Sole- 

 reder, in his Comparative Anatomy of Dicotyledons. The leaf 

 contains about 67 of these pores per sq. mm. on the upper sur- 

 face, and about a similar number on the lower surface. The 

 arrangement of the trichome is a peculiar one. Nothing quite 

 like it has been described as far as is known by the writer. 

 Trichomes similar in shape are of common occurrence — 

 especially is this true in the family Malpighiacese — but none 

 of them has become differentiated to such an extent as is 

 found in the trichome of Janusia. It is uncommon to find 

 a hair on the leaf with the walls cellulose throughout. Sole- 

 reder describes a hair having a cellulose membrane around it. 

 The hair of Janusia difi'ers from this in that the walls of its 

 hairs are all cellulose except at the base of the stalk. 



Many examples of trichomes are found whose structure is 

 very similar to that of Janusia. Examples of Ranunculacese 



