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TEXTBOOK OF BOTANY 



climbing plants are found in largest numbers and grow to 

 the greatest size. Running from tree to tree, they often form 

 an inextricable tangle that reaches to the tops of the tallest 

 trees. Many climbing plants, like the bean, have twining 



stems. Most of them, 

 whether their stems twine 

 or not, also have special 

 organs that fasten them 

 to supporting objects. 

 Some, like the English 

 ivy, have short adventive 

 roots that grow into the 

 crevices of walls, fences, 

 or rocks . The adventive 

 roots of some tropical 

 climbers grow like tight 

 girdles about the trunks 

 of trees upon which the 

 plants are climbing. 

 Many climbing plants 

 have tendrils (Fig. 128) 

 similar to those of the 

 cucumber ; and others 

 are assisted in climbing by the possession of thorns or 

 prickles. 



218. Horizontal Underground Stems. Many seed plants 

 have underground woody stems. In some cases these stems 

 are long and slender and grow horizontally from year to year 

 like the stem of the bracken fern. The common may-apple 

 (mandrake) has a stem of this sort. The parts of the plant 

 that push above ground live for a single season, and the 

 underground stem is the only part of the plant that lives from 

 year to year. Adventive roots arise here and there upon the 

 lower side of the stem. This stem, like an erect stem, bears 

 leaves ; but they are small, dark-colored scales. In the axil 



FIG. 119. Climbing stem of a tropical 

 plant. The branches grow into union 

 where they touch one another, forming a 

 lattice-work about the supporting stem. 

 After Kerner. 



