Scrophulariaceae and Orobanchaceae 159 



arated from one another, and increased in size, averaging 4 to 

 6 times the size of the lower ones. Sections made in the region 

 of the crowded small scales show numerous patches of hard 

 scleroid cells and the inner almost continuous ring of bundles, 

 while in the position of the outer ring some fairly recognizable 

 bundles are seen. Above this point the two rings of bundles 

 become complete and the scleroid patches disappear; below this 

 point the bundles become fewer in number and less recogniz- 

 able, but the scleroid patches increase in number until in the 

 tuberous part scleroid patches are the predominant feature and 

 the bundles as such disappear. Evidently the lower part of the 

 aerial portion represents a transition from stem axis to aerial 

 shoot, and so, this part together with the upper part of the tub- 

 erous swelling might be considered as the stem axis. As in 

 Epiphegus, stem system and root system have become con- 

 fluent with no sharp line of distinction between the two. 



Stomata have been reported absent from the scales but sev- 

 eral were found on the lower or outer surface of the upper scales. 

 From their shape they appear to be almost or quite function- 

 less (Plate XV, Fig. 28). They are misshapen and poorly de- 

 veloped; some have two elongated guard cells which have 

 slipped out of position and show a long orifice between them, 

 others have three and four guard cells very loosely fitted to- 

 gether. Large multicellular and unicellular hairs are found on 

 the edges of the scales which the drawings (Plate XV, Fig. 31) 

 will sufficiently indicate. 



The histology of the flowering axis is interesting for several 

 reasons. The cortex and pith areas are quite large and consist 

 of rounded cells of varying size and thickness with frequent 

 large intercellular spaces. Some of the cells have contents while 

 others are empty. Two definite rings of bundles surround the 

 pith, which have a zone of fundamental tissue intervening. 

 This quite agrees with Wilson's observations (25, p. 14) but dis- 

 agrees with those of Chatin (26, p. 590) who says that Epiphegus 

 and Conopholis have three rings. The majority of bundles 

 in both rings are completely separated from each other by fun- 

 damental tissue, and this represents the climax in the series, 

 beginning with Harveya in which the bundle system shows no 

 tendency toward separation of bundles, thence to Orobanche 

 which shows indications of such, thence to Aphyllon in which 



