

ioo BOTANICAL GAZETTE , [February 



protection of the middle stem leaves and the middle rosette leaves 

 are compared, the preponderance of protection is in favor of the ro- 

 sette leaves. However, it must be borne in mind that the difference 

 in thickness of wall and cuticle in a number of instances is so slight 

 as to be almost negligible. Moreover, in notable instances the stem 

 leaves have a decidedly thicker wall and cuticle. This is true of 

 Chrysanthemum Leucanthemum, Capsella Bursa-pastoris, Artemisia 

 caudata, Satureja glabra, Scutellaria parvula, and others. Chrys- 

 anthemum has broad, spatulate rosette leaves on long slender 

 petioles, while the stem leaves are oblong or oblanceolate, and have 

 a decidedly xerophytic form and structure. The stem leaves of 

 Lepidium, Capsella, Satureja, and, to a certain extent, Scutellaria, 

 in like manner have a decidedly xerophytic form and structure as 

 compared with their corresponding rosette leaves. Artemisia is 

 one of those sand dune xerophytes whose stem and rosette leaves 

 are finely dissected and almost equally exposed, and hence almost 

 equally xerophytic in form and structure. In such mesoxerophytes 

 as Verbascum Thapsus, whose leaves are thoroughly protected by 

 a woolly coat of branching multicellular hairs, the difference in 

 protection of stem and rosette leaves is also slight! Some plants, 

 therefore, seem to have xerophytic shoots and mesophytic rosettes; 

 others show a tendency to xerophytic rosettes and mesophytic 

 shoots; while in still others the distinction is not evident. 



Chlorenchyma 



The apical, middle, and basal stem and rosette leaves of certain 

 plants were studied with a view to determining the similarities and 

 differences of the chlorenchyma of the corresponding regions of the 

 stem and rosette leaves of the same plant. For example, an 

 apical stem leaf and an apical rosette leaf would be selected for 

 comparative study. Sections through the apical region of the 

 stem leaf were then studied and the results compared with those 



obtained from a similar 

 rosette leaf. Sections th 



the 

 the 



leaves were similarly studied and compared. After the apical 

 leaves were thus studied, the middle stem and middle rosette leaves, 

 as well as the basal stem and basal rosette leaves, were similarly 



