224 



two or three times. The tertiary series of branches and the 

 upper ones of secondary order are apparently always short 

 (up to about 4 centimetres) and rarely have more than 2 or 

 3 internodes. It seems as if growth were interrupted by the 

 drying up of the terminal bud. Each of these small branches 

 bears one or two flowers. 



The lower leaves are lanceolate-linear and may attain 

 a length of about 3 centimetres; the upper ones are small 

 scales, so that the plant is thus practically leafless. All the 

 green parts are covered with slanting bipartite hairs similar 

 in form to those of C. erinaceus (see fig. 53). 



The white flowers open in June. The capsule contains 

 two large, long-haired and hard-shelled seeds. 



I had no opportunity of examining the anatom}^ of the 

 leaf. The primary cortex resembles that of the next species. 

 The epidermis consists of one layer and contains tannic acid ; 

 the stomata are not sunk. There are three layers of palisade 

 cells which towards the interior are supported by one or a 

 few layers of tangentially extended cells, almost devoid of 

 chlorophyll, and among these are a few bast cells opposite 

 the groups of phloem. 



Convolvulus divaricatus Rgl. & Schm. 



An undershrub which grows on stationary sand. The 

 year-shoots, about 30 40 centimetres in length, are sinuous, 

 white-woolly and two or three times branched. The leaves 

 are small, (5 to 15 mm. long) and with a broad cordate 

 base. 



The isolated white flowers open in May. 



The structure of the leaf is isolateral. About five layers 

 of palisade cells occur, the middle ones being the smaller. 

 The epidermis is one-layered and contains tannic acid. Both 

 surfaces are covered with long projecting hairs which are 

 bipartite but one arm is much reduced. Alongside the veins 

 there are secreting cells (laticiferous cells). The structure of 

 the green cortex of the young branches is similar to that of 

 the previous species, but the hairs are erect and the coating 

 is much denser. 



