28 A TEXT-BOOK OF BOTANY 
thesis, and this process is carried on by the green tissue of 
the globular, cylindrical, or flattened stems (Fig. 25). 
wes , fj . ay 
Sie ease ve ee DE ane =e olen eae 
Fic. 25.—A globular cactus, with ribbed stem bearing spines and no foliage leaves. 
cor 
(6) The roseite-habit (§ 12) is a very common method of 
protection used by small plants growing in exposed situa- 
tions, as bare rocks and sandy ground. The clustered 
leaves, flat upon the ground or nearly so, and more or less 
overlapping, form a very effective arrangement for resisting 
intense light or drought (Figs. 6 and 7). 
