June 1, 1913.] 



THE INDIA RUBBER WORLD 



467 



Possible Rubber Producers in the Temperate Zone. 



By Charles P. Fox. 

 A PAPER READ AT THE THIRD INTERNATIONAL RL^BBER CONFERENCE, HELD IN NEW YORK. 1912. 



Tins paper has been prepared at the suggestion of Mr. H. C. 

 Pearson, originating from comments made upon an edi- 

 torial in a recent issue of the India Rubber World. 



Tlie idea of producing rubber in commercial quantities within 

 the boundaries of the Temperate Zone is not a new one. The 

 increasing use of this commodity and the increase in cost are re- 

 sponsible for the occasional stimulation of interest in the matter. 

 Thirty years ago the farmers of Canada were forming companies 

 for utilizing the common milkweed for this purpose. The high 

 price of rubber in 1910, caused some Summit County (Ohio) 

 farmers to seriously think of the same thing. 



While the proposition is quite possible, its probabilities are 

 remote, and dependent upon many conditions, some of which are : 

 demand, cost of production, grade of product, influence of sup- 

 phcs of natural and plantation-grown rubber and the ever-appear- 

 ing spectre "synthetic." 



We have several rubber-producing plants suitable for the vari- 

 ous sections of the temperate zone. During the past fifteen years 

 the author has examined a number of plants, the examination 

 inchiding ahnost every plant likely to contain rubber, from 

 Carolina Palmetto to California Cactus. For convenience I have 

 grouped these plants according to their nativity and climatic 

 requirements. 



Of the foreign plants we have Atractylis and Eucommia. 



Atractylis gummifera is a thistle-like Composita of Southern 

 Europe with enormous beet-like roots and thorny leaves. A few 

 years ago European writers advocated this plant as a source of 

 crude rubber. Our examination did not confirm this view. 

 ' Eucommia ulmoides, known as the "Chinese Rubber Tree," is 

 a native of Northern China, a country very similar in soil and 

 climate to Eastern Washington. According to the Arnold 

 Arboretum, Harvard College, it is perfectly hardy in New 

 England. Just what it will do in this section in the production 

 of rubber either in quality or quantity, is not given out by the 

 authority quoted. Under natural conditions, it produces a good 

 rubber, the rubber appearing as long silky threads in the broken 

 bark. This source of rubber has been known since 1882. It has 

 been recommended for planting by the Indian Forestry Com- 

 mission. According to Vilmorin, Paris, who propagated it for 

 sale, there was never much demand for it. It is a fine appearing 

 tree and well deserves a place in ornamental forestry. 



Of our native plants those of possible value as rubber pro- 

 ducers in the North are members of the Asclepiadaceae, Apocy- 

 naceae, and Compositac families. 



Of the true milkweeds there is only one of any importance, 

 Asclepias cornuti. This species is very abundant throughout the 

 United States, growing upon almost any kind of soil and showing 

 great drought-resisting qualities. This plant contains an abund- 

 ance of milky juice containing 3' per cent, of fair grade rubber. 

 The cost to collect this latex is, however, prohibitory. The 

 amount of product given up by extraction of either the fresh or 

 dried weed is too small, and its character too inferior to command 

 much attention. 



If by selection or transportation from one section to another, 

 the quantity and quality could be increased and improved to a 

 degree sufScient to make the production by extraction profit- 

 able, this plant would be the favorite, as perennial plantations 

 yielding annually 2 to 3 cuttings of at least 10 tons each per acre 

 of green weed, could be easily and economically established. 



The common Indian hemp. Apocynum cannabinum. occupies 

 about the same territory as the milkweed but is less abundant. 

 It produces less latex than the milkweed, but the quality of rub- 



ber is better. The root of this plant contains rubber, and is very 

 similar to that of the African Landolphia. 



The native Compositae of this region give us several rubber 

 producers. Souchus (Sow thistle), an introduced species now 

 naturalized, is credited by Jumelle as the producer of an excel- 

 lent grade of rubber. Souchus rubber is the subject of a Ger- 

 man patent of 1885. This plant thrives on a dry, barren soil 

 and is regarded as a troublesome weed. 



We have two species of wild lettuce, Lactuca Canadensis and 

 /-. virosa; both very abundant, especially the latter, which is a 

 terrible pest. Both produce thick rubber-containing latex and 

 medicinal agents. L. i-irosa gives a water extract similar to 

 chicory as a coffee substitute. 



The arid section of the Temperate Zone is amply provided for 

 with guayule, pingue, greascweed and candelillia. 



The value of the guayule {Parthenium argentatum) as a rub- 

 ber producer is too well known to need a description. Prof. 

 Lloyd is certain that guayule can be successfully grown in 

 Mexico. Mexican conditions can certainly be duplicated in the 

 Southwest. 



Pingue (Actiiiella Richardsonii) is a related plant found in 

 New Mexico and southern Colorado. While containing less 

 rubber than guayule, it possesses some superior advantages in 

 other ways. The root of the pingue is the producing portion. 

 The top furnishes numerous shoots for propagating. The pingue 

 requires a deep, sandy soil for the maximum development of its 

 long tap root. Under these conditions the yield of rubber may 

 reach 7 per cent, of good grade rubber equal to. if not better 

 than, the guayule product. 



While investigating the pingue, this peculiar condition was 

 observed : As before stated, the pingue, under natural condi- 

 tions, i. e. mountain slopes and dry sandy banks, develops a fusi- 

 form type of root, comparatively rich in rubber. On clay soil, in 

 meadows along irrigating canals, the pingue root becomes fibrous 

 and contains little or no rubber. This phase may have an im- 

 portant bearing upon the utilization by cultivation of the guayule 

 and pingue for the production of rubber. 



The neglected mariola, another Parthenium, occupying a wider 

 range and much more abundant than guayule, may sometime be 

 of value on account of its resin. Nevada greasewood contains 

 rubber as shown by the Ellis & Werner patents of 1902. Mr. 

 Sam P. Davis, Nevada Industrial Commissioner, advises that 

 there is a large amount of this plant. 



Another promising plant of the arid region is "Strockles 

 Rubber Bush," a robust Composita growing abundantly through- 

 out the Great Basin. While the rubber of this plant is inferior 

 to that of the other two Compositae mentioned, it can be 

 utilized. This plant also contains a large amount of valuable 

 resin. 



In North Mexico and the "Big Bend" country of Texas, there 

 is an immense growth of Candelillia, an Euf'horhia which con- 

 tains rubber and wax. This wax is now a commercial product 

 much used in Germany as a constituent of hard rubber. On 

 account of its drought-resisting qualities and the facility by 

 which it can be propagated by its bulbous root, it should be a 

 valuable plant for the extremely arid, non-irrigated section of the 

 Southwest. 



The South has its special rubber producing plants. Some 15 

 years ago the growing of Ficus elastica for rubber was attempted 

 in Florida. The point selected, unfortunately, was on Key West, 

 a small island near the mainland, with shallow soil and dry 

 meteorological conditions. 



