25 
IX.—COLORADO RUBBER. 
(Hymenoxys sp.) 
[K.B., 1906, pp. 218-219.] 
Early in 1994 a correspondent forwarded to Kew an extract 
from the Denver Post of 26th November, 1903, which gave a 
somewhat enthusiastic account of the discovery by a prospector 
in Colorado of a rubber-yielding plant. This was spoken of as 
occurring abundantly in the hills and mesas in the vicinity of 
Salida, the belt extending into the San Luis Valley, Gunniston 
eas and as far south as New Mexico. In June, 1905, 
. E. Naylor, of Bradford, presented to the Museum at Kew a 
Pa dn of the dried plant, together with samples of crude and 
manufactured rubber obtained from it. Mr. Naylor eM 
also communicated seeds of the plant 
Mr. T. D. A. Cockerell, to whom the Museum is also indebted 
for specimens of the plant and of its rubber, published an account 
the species in the Bulletin of the Colorado Museum for 
December, 1903. The plant, which is a Meis of the natural 
amily Compositae, i is there identified as Picradenia floribunda, 
utilis, which Mr. Cockerell considers to be part of the aggregate 
Actinella Richardsoni. Subsequently, in the Bulletin of the 
h 
indicated ud Picradenia may be considered a subgenus of 
Hymenoxys, Cass. If this view be correct the Colorado Rubber 
plant is therefore a species of Hymen dett 
In July, 1906, Mr. Naylor forwarded to Kew a further supply 
of material. Accompanying this was the following extract from 
the letter which Mr. Naylor had received with the specimens :— 
I s er i 
kept in a warm plac e will Deonue adit and sticky. The round 
piece is just as it rand from the plant; the flat piece is after its 
second trip through the machine, and in this form is shipped east 
to the refinery. The full size of the pieces as shipped is 10 to 15 
- long and 18 inches wide. The root of the native plant yields 
ut 10 per cent. of rubber 
From the evidence em obtained there is hardly room for 
doubt ME this species of Hymenoxys yields a rubber-like 
product. This does Sok hea compare favourably with many 
of the lower grades of rubber already on the market. It is there- 
fore somewhat doubtful whether the expectations which haye 
been formed regarding it in some quarters will be realised. 
