ENDOGENS. 131 



tribe. In the latter tribe are placed the Dragon-trees, 

 the most gigantic of the order. There is one in the 

 Island of Teneriffe which is described as seventy feet 

 high and forty-six feet in circumference at the base. 

 The flowers are small. From some species of Dragon- 

 tree the Sandwich Islanders prepare an intoxicating 

 liquor called ava. 



The inspissated juice of several species of Aloe is used 

 in medicine as a cathartic, and the bulb of the Squill is 

 imported from the coasts of the Mediterranean, and is 

 valued for its diuretic, expectorant, and other properties. 



A species of Onion called Camass is used by the In^ 

 dians of Oregon as food. 



Textile fibers are procured from New Zealand flax 

 (Phormium) and from the Yucca, or Adam's needle. 



10. The SCREW-PINE family (Pandanus) contains sev- 

 eral species which exhibit a semblance of 



instinct in the development of aerial roots 

 at different distances on the stem, by which 

 their life is prolonged. Their leaves are 

 arranged in a spiral, hence the name, 

 Screw-pine. 



11. The ARUM family contains the 

 Cuckoo-pint tribe, the Bulrush tribe, (Fig. 

 55,) the Sweet-flag tribe, and the Duck- 

 weed tribe. In the Duckweed (Lemnd) 

 we see at a casual glance nothing but a 



green scale floating on the water, which is FlG>55 '~~ ] 

 in reality a compound of both root and stem. A careful 

 observation in summer may lead to the discovery of mi- 

 nute straw-colored anthers on the edges of the plants, 



