290 



THE INDIA RUBBER WORLD 



wood rublier. (,Der Tropeii-flanzer, Sept., 1905, \i. 54U.) Tliis 

 view has the support of Professor Francis E. Lloyd,- who be- 

 lieves in its Aztec origin. 



DESCRIPTION OF THE GUAYULE SHRUB. 

 The Parthcniuin argoilatitm Gray, is the only present rubber 



A. Stapf prepared the folic 



Gati 



producer fciuiid among the composites. It is a woody shrub of 

 spreading habit, naturally growing much branched. If the branches 

 die away at the base, a distinctly treelike form is assumed. Large 

 plants may acquire a spread or height of 3 feet or more, 

 but such individuals are of advanced age, probably not less than 

 40 or 50 years old. The small leaves are greenish, silvery gray, 

 as also are the younger twigs, which, as the age of the axis 

 advances, change to light and then to dark ashy gray. The 

 winter appearance of the plant is strikingly different from the 

 summer appearance. In the winter the leaves, save those form- 

 ing small clusters at the tips of the twigs, have fallen, leaving 

 these bare. In summer the new growths are clothed with 

 leaves of maximum size in which the green color is more ap- 

 parent. At this tiine the flowers are borne in loose clusters on 

 slender stems and crown the plant with a profusion of small 

 yellow blossoms. These are arranged in heads, each head re- 

 sembling a small daisy and capable of forming at most five 

 seeds. Usually some of these do not develop. A curious man- 

 ner of development results in the association with the seed of a 

 large amount of chaff. 



A i)hinl tliat is not a rubber producer, the mariola (Par- 



Loading Wagon with Guayule. 



thenium incanum H. B. K.), grows often side by side with the 

 argenlalum and is mistaken for it. To prevent confusion, Dr. 



»"Gu?yuIe, a Rubber Plant of the Chihuahuan Desert," by Francis E. 



ting comparison ; 



Parthc\ 



\ small shrub with a short stem 

 ind very numerous, much divided 

 Ijranches. from less than 1 foot to 

 aver 3 feet high; woody iK-rsistent 

 branches, short, more or less 

 gnarled, covered with a rather 

 smooth, dark gray bark, young 

 shoots silvery gray all over. .' 



to S coarse 

 'A inch long, 



ito an open 



ssile. subglo- 

 .r, 3 to 7 in 



der branches, 

 y imperfect 



broadly herbaceous 



to 2 feet high, 

 oody persistent 

 slender, covered 

 ifih bark, crack- 

 young shoots 



obovateoblong 

 the smaller) to 

 H to 1 inch 

 'A to H inch 



obtuse, tiic whole leaf densely cov- 



when young, then grayish; petiole 



Flower heads shortly pcdiincled. 

 or subsessile, 2 lines in diameter in 

 terminal, often nuich branched 



branches slender. 



Involucre finely villous: outer 

 bracts slightly herbaceous on the 

 back, above the middle. 



• Juite recently another species, discovered by Professor F. E. 

 ' >d, has been named Parthcnium Lloydii. Professor H. H. 

 iiilett thus describes the new species, emphasizing- the differ- 

 ccs between it and the Parthcnium argcntatum as follows: 





the Partheninm argentatum the m 

 nated by the development of the ft 



system takes place at the base of the we 

 ;rowth at that point of two or three branc 

 mated by inflorescences. As a result of th 



and peduncle, the branching of old plar 



al growth of the seedling is 

 rescences. Extension of the 

 Il-diflferentiated peduncle, by 

 les. whose growth is in turn 

 is sharp delimitation of leafy 

 ts. is closely and repeatedly 



A Guayule Baling Press. 



divaricate. Grown plants are often finely symmetrical. In Furthenium 

 Lloydii the branching is like that of the mariola (P. incanum"). The stem 

 is more slender than P. argentatum, and the leafy penduncle is not sharply 

 delimited. 



bears short, leafy 

 \ grown 

 ricate interweaving of branches. 

 :nce between the two specimens 

 argentatum are relatively only 

 deeply lacinate, whereas in P. 



Well up toward the infloresce 

 elongate afte,- the closing of the i 

 /'. Lloydii is therefore characteriz. 

 In herbarium specimens the strikii 

 lies in the form of the leaves, wh 

 half as wide as in P. l.loyiUi an 

 Lloydii they are typically sparsely 



In the type material of P. Lloyi 

 toward the base, but diverge at tl 



dentic 

 he pappus aw-ns are 



riot'h. 



and 



5f P. 



incurved at the apex. This distinction pointed out by Professor Lloyd does 

 not ^eem to hold throughout the large series of specimens of P. argentatum 

 in tlic l.ray and the National Herbaria, but in view of McCallum's recent 

 r. port that the guayule consists of as many as 125 segregable elementary 



'Mrs. the occasional inapplicability of this character is not to be wondered 

 I he curvature of the pappus may serve to distinguish P. Lloydii from 



itiiii segregates, but not from others. 



RUBBER CONTENT. 



I hiaynlc is distinct from most other rubber-producing plants 

 m that its bark contains no latex, rubber being in the cellular 

 tissue of the epidermis and to a small extent in the branches 

 and leaves, the blossoms being without traces of rubber. The 

 amount of rubber in the topmost branches is very slight, but 

 increases toward the roots. The bark also contains resins and 

 essential oils, which decrease the value of the rubber. Fairly 

 dry plants subdivide into the following weights: 



