20 Contributions from the Gray Herbarium 
generalized and by far the largest group of species, the subseries 
Euaureae, occurs from Ecuador to Chile, Argentina, and Brazil, 
covering practically the whole South American range of the genus 
(except Colombia and Venezuela, where the two known species, 
both endemic, belong to the typically Mexican and Central 
American section Diplostichis), and shows in various species in- 
dications of the features which, carried to a greater extreme in 
certain other groups of species in various parts of its range, are 
taken as the basis for their separation into series, sections, and sub- 
genera. It seems probable therefore that all these other groups 
confined to South America (sect. Paradosa and Trichophylla of 
Calanticaria, and subgenus Yerbalesia) have been derived from the 
Euaureae or a group like them. Although the pappose species of 
Mexico and Central America (including also the single endemic 
species of the United States, V. reticulata, and the two related 
species of Colombia and Venezuela) are much fewer in number (46 
as opposed to 74) than those of South America, they offer a far 
wider range of forms; nor is there any species or group of species 
which shows very close connections with the South American types. 
Of them all only the series Grammatoglossae and Dentatae of the 
section Chloracra afford in habit and involucre any evidence of 
close affinity with the South American Euaureae and so with the 
probable parent stock of the genus. 
On the basis of the reduction of the species of Heliomeris (Gym- 
nolomia auct.) to the related genera, the following key to Viguiera 
and related groups is put forward as being more in accord with the | 
true genetic affinities of the plants concerned than the one given a 
on page 6. It will be noted that the only point of real ambiguity — 
is in the distinction between Viguiera (section Diplostichis) and 
Hymenostephium, and that this is due to the inclusion in each group 
of species with calvous achenes. It is believed, nevertheless, that . 
in this as in other similar cases in Compositae the apparent oblitera- 
tion of generic lines by epappose species, which on other characters, 
scarcely capable of sufficiently precise statement for use in a key; 
can be definitely referred to one or other of the genera concerned, 
should not prevent the recognition as independent genera of groups 
which in their pappus-bearing forms are perfectly distinct. 






