454 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1911. 



guilla), a congener of the mescal but a smaller plant, yields a fiber 

 which is twisted into rope and twine in Mexico. It covers many 

 miles of the desert of western Texas, although in that region little 

 effort has been made to utilize it. It barely reaches southern New 

 Mexico and can never be of economic importance here. 



Recent advances in the price of rubber, caused by its increased use 

 in manufactures, have stimulated a search all over the world for 

 rubber-yielding plants. A large and profitable industry has been 

 developed in northeastern Mexico in the extraction of rubber from 

 one of the Compositse known as guayule (Partlienium argentatum). 

 It has been reported repeatedly that guayule occurs in New Mexico, 

 but such statements are not supported by investigations. Although 

 the sections of the State where it might be expected to grow have 

 been carefully explored by botanists searching for it, not a single 

 plant has been found. Another species of the genus, mariola {Par- 

 ihenium incanum), from which rubber can be extracted, does occur 

 in New Mexico on the dry limestone hills near the southern border. 

 It is said to yield a fair quality of rubber, but a lower percentage of 

 inferior value to that obtained from guayule. Nowhere in the State 

 is it found in sufficient quantity to be of commercial importance. 



Another member of the same family, the Colorado rubber plant 

 (Ilymenoxys floribunda) is abundant in northern New Mexico, where it 

 covers hundreds of acres on the low foothills or higher up among the 

 pine trees, sometimes to the exclusion of almost all other herbaceous 

 vegetation. By chewing some of the stems for a few minutes a small 

 mass of crude rubber is obtained. A few years ago a company was- 

 formed in Colorado to extract rubber from the plant, but the under- 

 taking was not a success. While there is no doubt that rubber can 

 be gotten from this source, it is questionable whether a large enough 

 supply could be relied upon to make extensive operations practicable. 



A prominent feature of the deser.t flora of the Southwest, along the 

 rocky hills or advancing upon the plains, are the stately Agaves, gen- 

 erally known as mescal or century plants, several species of which 

 are at home hi New Mexico (pi. 1 0) . Their leaves are broad and short, 

 never more than 18 inches long, succulent, forming a compact rosette. 

 Each is tipped with a sharp dark spine and is armed along the edges 

 with stout hooked prickles. The tall flower stalks of our native 

 species are 10 to 15 feet high or more, surmounted by thick divergent 

 branches bearing hundreds of yellowish flowers. It is a popular 

 belief that the century plant blooms but once, when it has rounded 

 out a hundred years, hence the common name. A possible basis for 

 this reputation is that in cultivation the plants seldom flower, 

 although in their native haunts flowering plants are of common 

 occurrence. They are known to bloom long before they attain the 

 century mark and probably require only a comparatively few years 



