SOME PLANT UiOGEAPHIES. 203 



large, thick, and fleshy. But as they grow in 

 the hot and dry cHmate of Mexico, an ahuost 

 desert country, with a very small rainfall, they 

 have a particularly hard outer skin, so as to 

 prevent undue evaporation ; and they are pro- 

 tected against the attacks of herbivorous animals 

 by being spiny at the edges, and ending in 

 a stout and dagger-like point of the most for- 

 midable description. The centre of the plant 

 is occupied by a sort of sheath of leaves, con- 

 cealing the growing point. For several years 

 the round bunch of outer leaves grows bigger 

 and bigger, till it attains a diameter of ten or 

 fifteen feet at the base, seeming still like a huge 

 rosette, with, hardly any visible stem to speak of. 

 Meanwhile the:>e huge leaves are busy all the 

 time, eating and assimilating, and storing up 

 manufactured food- stuffs as hard as they can in 

 their thick and swollen bases. After six or 

 seven years in their native climate, the plant feels 

 itself in a position to send up a flowering stalk, 

 which is formed from the materials already laid 

 by in these immensely thick and richly- stored leaf 

 bases. The stalk springs from the middle of the 

 central leaf -sheath. In a very few weeks the 

 agave has sent up from this point a huge flower- 

 ing scape, twenty or thirty feet high, and a foot 

 or fifteen inches thick at the bottom. On this 

 scape it produces with extraordinary rapidity a 

 vast number of large and showy yellow iflowers, 

 which look not unlike an enormous candelabrum, 

 with many divided branches. The plant is 

 enabled to produce this immense flowering stem 

 and these numerous flowers in so short a period, 



