- 268 THE FORMATION 
character will show in different parts of the world a vegetation taxonomically 
-very different. It may some day be possible to use a binomial or trinomial 
for this purpose, somewhat after the fashion of taxonomy, in which the 
habitat name will represent the generic idea as applied to formations, and 
a term drawn from the floristic impress the specific idea. Such an attempt 
would be futile or valueless at the present time; it could not possibly meet 
with success until there is more uniformity in the concept of the formation, 
and until there has been much accurate and thorough investigation of actual 
formations, a task as yet barely begun. At present, it seems most feasible 
as well as scientific to designate all formations occupying similar habitats 
Fig. 69. Aspen forest formation (Populus-hylium), the typical stage 
of burn successions in the Rocky mountains; it is sometimes an anom- 
alous stage in primary successions, interpolated in place of the thicket 
formation. 
by a name drawn from the character of the latter, such as a meadow forma- 
tion, poium, a forest formation, hylium, a desert formation, eremium, etc. 
A particular formation is best designated by using the generic name of one 
or two of its most important species in conjunction with its habitat term, 
as Spartina-Elymus-poium, Picea-Pinus-hylium, Cereus-Yucca-eremium, etc. 
Apparently a somewhat similar nomenclature is adapted to successions. 
The cause which produces a new habitat may well furnish the basis for 
the name of the general groups of successions, as pyrium (literally, a place 
