Scrophulariaceae and Orobanchaceae 157 



in places the bundles are separated; the amount of phloem is 

 about twice that of the xylem and consists of hard and soft bast; 

 the xylem has a few spiral tracheae and pitted vessels, that we 

 best see in longitudinal sections. 



The vegetative axis of Aphyllon (Plate XIII, Fig. 16) is 

 reduced in thickness to scarcely more than one-fourth of an inch, 

 or usually less, but in length is about one inch. The number of 

 scale leaves is reduced to from 5 to 10, alternately placed and 

 separated on the stem; they are smaller than the scales of Oro- 

 banche and decrease in size from the upper to the lower ones. 

 The lower ones have neither stomata nor hairs, while the upper 

 ones have both. The hairs are capitate and multicellular, like 

 those of Harvey a and Orobanche. 



In making cross sections of the stem their soft and fleshy nat- 

 ure is at once recognized. The epidermis consists of small cells 

 which are thickened on the free side; amongst these, stomata 

 may be seen. The most conspicuous feature of the stem is the 

 unusually large rounded thin-walled cells in the cortex and pith. 

 Both regions are wide in extent and their cells are packed with 

 large starch grains. Between these regions a comparatively 

 narrow ring of bundles is arranged. The bundles are more wide- 

 ly separated than in Orobanche, thus making the medullary 

 rays quite wide. Around the bundle system is a sheath of from 

 2 to 4 layers of cells, much smaller than the cortex cells and 

 whose greater diameter is placed in a tangential direction. The 

 excess amount of phloem over xylem is more pronounced than 

 in the previous two genera. The phloem is external and xylem 

 internal, the latter composed of a few spiral tracheae and pitted- 

 reticulate cells. 



Transverse sections of the flower stalk show the same arrange- 

 ment of tissues as in the stem. The bundles are placed in a nar- 

 row ring about the pith and internal to the cortex; the xylem is 

 slightly better developed than in the stem, while the phloem 

 forms a continuous zone about the xylem. Cortex and pith 

 have some starch grains. The epidermis, of small cells with 

 free walls heavily thickened, is frequently interrupted by cells 

 in groups of two slightly raised above its surface which appear 

 to be stomata. Glandular capitate hairs, arising in great num- 

 ber from the flower stalk, have also two cells forming their base. 



In Epiphegus (Plate XIII, Fig. 7) the vegetative stem and 

 enlarged primary root tubercle become confluent into an oval 



