i 211 
from the land, and that the evaporation of water from the Castilloa 
tree is likely to be less than from ordinary shade trees, speak in 
favour of its extensive planting among cacao. 
“It has often been stated that Castilloa elastica, under cultivation, 
will not yield rubber in paying quantities. It would go beyond 
our object on this occasion to enter into a description of the methods 
and economies of rubber tapping; we therefore limit ourselves 
to stating that, if the right varieties be chosen for planting, excellent 
returns may be obtained.” 
Guayule Rubber.—An account of this Mexican source of Rubber, 
derived from Parthenium argentatum, A. Gray, was published in the 
Bulletin 1907, pp. 285-294, with a further note in the Bulletin for 
1908, p. 255. In 1907 some seeds of Parthenium argentatum and 
also of P. incanum,—a species sometimes confused with the rubber- 
yielding plant (cf. K.B. 1907, p. 294)—were received from the 
United States Department of Agriculture. The plants of Guayule 
raised from these seeds are now about 18 imches high and in flower, 
the stem is woody below and the silvery leaves, 2 inches long, are 
lanceolate, entire or in a few cases irregularly lobed or toothed. 
The plants of P. incanum have glaucous or silvery hawthorn-like 
leaves and in their crenate lobation differ markedly from the leaves 
of P. argentatum where the lobes are sharply angular. 
Through the kind offices of Mr. Reginald Tower, H.M. Minister, 
Mexico, two consignments of the seeds of Parthenium argentatum 
were received at Kew in March and April of this year. The first 
consignment was sent to Mr. Tower by Mr. J. E. Kirkwood of the 
University of Montana, Missoula, the author of a paper on the 
“ Propagation of Guayule by seeds” in the American Review of 
Tropical Agriculture, vol. i, No. 2, February, 1910, pp. 34-43. 
he second consignment of seeds was sent by Mr. Tower from 
Mr. G. Fleming of the Hacienda de Cedros, Mazapil, Zacatecas. 
The bulk of the seeds so received has been distributed to Mysore, 
Baroda, Poona, Lahore, Ceylon (Hakgala), Sudan, Pretoria, 
Nairobi, Queensland, Port Darwin, Adelaide, Sydney and the 
Antilles. 
The germination of the seeds retained at Kew has been good ; the 
plants raised from the later sending in April are now 6 inches high 
and bear somewhat silvery, oblanceolate, slightly lobed leaves 3-4 in. 
long. The older seedlings are a foot high, the whole plant being 
covered with a fine silvery-grey tomentum; the leaves are 2-5 in. 
long, narrowly lanceolate and irregularly lobed with angular acute 
or subacute lobes. Some of the plants, which are already shewing 
flower heads, have been placed in the Succulent House. a 
In the Bulletin 1908, p. 255, a despatch from H.M. Minister, 
Mexico, was published, in which the Guayule Kubber industry did 
not appear to have a very bright future; a further despatch 
received from Mr. Tower, early last year, indicates that the 
industry is still in a flourishing condition. e Mexican Rubber 
Exploitation Company now have a large Guayule factory established 
in the State of Coahuila and with a new process for the extraction 
