EPIPHYTES OR AIR-PLANTS. 



89 



original bole and supporting the wide-spread canopy of branches 

 and foliage. Very similar is the economy of the Mangrove (Fig. 

 118), which inhabits muddy sea-shores throughout the tropics, and 

 even occurs sparingly on the coast of Florida and Louisiana. Its 

 aerial roots spring both from the main trunk, as in the Pandanus, 

 and from the branchlets, as in the Banyan. Moreover, this ten- 

 dency to shoot in the air is shown even in the embryo, which be- 

 gins to germinate while the pod is yet attached to the parent 

 branch ; the radicle, or root-end of the embryo, elongating into a 

 slender thread, which often reaches the ground from the height of 

 many yards, before the pod is detached. In this manner the Man- 

 grove forms those impenetrable maritime thickets which abound 

 on low, muddy shores, within the tropics. 



132. Epiphytes, or Air-plants, exhibit a further peculiarity. Their 

 roots not only strike in the free air, but throughout their life have 

 no connection with the soil. They generally grow upon the trunks 



FIG. 120. Oncidium Papilio, and, 121, Comparettia rosea; two epiphytes of the Orchis 

 Family ; showing the mode in which these Air-plants grow. 



8* 



