(IO) 



of joints, either cylindric or broad and flattened. In Cereus 

 some species have the stems angled, and sometimes bearing 

 roots, while in others they are thick massive columns with 

 many longitudinal ribs ; in Echinocactus the plant-bodies are 

 but little elongated, or almost globular, while in other genera 

 the plant-body is covered with rows of spirally arranged pro- 

 jections. The flowers of many cacti are exquisite in form 

 and color ; they are borne on various parts of the plant-body, 

 in the turk's-head cactus on a curiously modified portion of 

 the apex. A plant of economic interest here is JVopalca 

 coccinellifera upon which the cochineal insect breeds ; it is 

 from these insects that the dye cochineal is obtained. 



On the remaining side bench is the stone-crop family 

 represented by many interesting and beautiful forms. The 

 echeverias from Mexico and Central America, and the sem- 

 pervivums, or house-leeks, from the Old World, are con- 

 spicuous among these. Many of the stone-crops are hardy 

 plants and a collection of these will be found at the herba- 

 ceous grounds. Only a few cactuses are hardy. 



House No. 6. This is also a desert house. On the two 

 corner benches to the right, as one enters from No. 5, is a 

 collection of century plants [Agave), a large genus known 

 only from the New World ; other and larger plants of this same 

 genus will be found in the central portion of the house. Con- 

 spicuous among these are : the thread-bearing agave, Queen 

 Victoria's agave, the sisal plant [Agave sisalana) ; and the com- 

 mon century plant [Agave americand). The first two are decor- 

 ative and curious ; from Agave sisalana is manufactured the 

 sisal hemp of commerce ; the last, Agave americana, is well 

 known, and it is from the sap of this, and of related species, 

 that the Mexican drink "pulque " is obtained by fermentation. 

 It is popularly believed that the century plants flower but once 

 in a hundred years, and then die ; it is true that the plant 

 dies when done blooming, but it blooms at a much earlier age 

 than a century, sometimes when but eight or ten years old, it 

 is said. A curious desert plant among the century plants on 

 the side bench is called by the natives of Mexico, its native 



