THE STEM. 



37 



ferns (fig. 34). In other cases an internode is more or less developed be- 

 tween each leaf, and the stem is marked by a succession of scars running 

 nearly round the stem (fig. 33), as in Mauritia and Astrocaryum vulgare- 

 in Geonoma and Chamcedorea the internodes are developed and the nodes 

 thickened, so as to appear externally somewhat like those of the stems of 

 Grasses, but they are not really articulated nor hollow like the latter. 

 The caudex of the Palms furnishing the common Cane (Calamus) is 

 chiefly distinguished from the last by the slenderness and extreme length 



Fig. 33. 



Fig. 34. 



Fig. 33. Palm-tret' (Areca) with unbranched caudex. 

 Fig. 34. An arborescent Fern with unbranehed caudex. 



of the internodes. Many of these Palm-stocks, which are simple in their 

 principal mass, send out axillary buds at or below the ground, which form 

 runners, and ultimately grow up independently of the parent. The aerial 

 stocks of a few branch high above the ground, as in the Doum-palm 

 and in Pandanus (fig. 10), where the terminal bud appears to undergo 

 successive bifurcations, but really sends off at intervals single axillary buds, 

 the development of which soon* equals that of the parent axis, and causes 

 the deflection of the latter so as to give a forked appearance. A similar 

 mode of growth is observed in certain Haemodoraceae (arborescent Mono- 

 cotyledons, natives of S. America), also in the Liliaceous genus Yucca. 

 The stocks of some of the Cactacese are undivided, as in Melocactus (fig. 

 36), Echinocactus, and Mamittaria, &c. ; but in others a few branches 

 arise, giving a compound character, as in various species of Cereus (fig. 

 37) and in the leaf-like stalks of Opwitia (fig. 35). Analogous structures 

 occur in foreign species of Euphorbia. 



