MONOCOTTLEDONES. 



169 



MONOCOTYLEDONES. 



i88. The Monocotyledones, so called since the em- 

 bryo has alternate leaves, of which the 

 first one developed is called a cotyledon, 

 are also called Endogenae, or Endo- 

 genous plants. A transverse section of 

 the stem (Fig. 281) shows that the fibro- 

 vascular bundles are isolated, numerous, zsi 



and scattered irregularly throughout the pith or funda- 

 mental tissue. Each bundle is closed ; that is, there is 

 no zone of meristem tissue (cambium) between the xylem 

 and phloem when these have reached their maturity, or 

 passed over into permanent tissue. In consequence of 

 this limitation of growth of the 

 bundles, the plants are generally 

 short-lived. In very young 

 plants, where the fibro-vascular 

 bundles are as yet few, their 

 general disposition, or arrange- 

 ment, may be seen. In the " Palm 

 type," which is illustrated in the 

 accompanying diagram (Fig. 

 282), the leaves supposed to be 

 opposite, and their bases united 

 with the entire circumference of 

 the stem. The numerous bundles 

 from each leaf pass obliquely 

 into the stem, and then descend 

 through the latter. The middle 



Fig. 281. Transverse section of an endogenous stem. Fig. 282. Diagram show- 

 ing the course of the fibro-vascular bundles in a stem from four successive leaves, 

 in case of the " Palm-type" 



