[Vol. 8 
126 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
with the approximate center of distribution without indicating 
the point of origin. Evidently much depends upon the char- 
acter of the species that are here concentrated. Near the place 
of origin might also be expected the most primitive species. 
Let us then examine the species found in central Texas. There 
are ten of these: L. auriculata, L. grandiflora, L. densiflora, L. 
Engelmannii, L. ovalifolia, L. argyraea, L. Fendleri, L. recurvata, 
L. gracilis, and L. Gordonii. These species, it will be seen, all 
belong to the section Zulesquerella and are those that have 
been considered among the most primitive in the genus. Six 
of them are annuals, two have auriculate stem-leaves and fila- 
ments with dilated bases, and seven show no inhibition of the 
terminal bud. Every species of this group has glabrous, spher- 
ical pods, and in none is the average number of ovules less than 
five. Not only are these species primitive, but in no other 
locality may be found anything like an equal display of what 
have been considered ancestral characteristics for purely mor- 
phological reasons. With central Texas as a center, if one were 
to draw on the map a series of concentric circles, each succeeding 
ring would have fewer and fewer species with primitive charac- 
ters. The periphery in general is bounded by highly specialized 
members of the genus. In a graphic representation of the sub- 
sectional groups they may be shown by lines radiating from a 
common center. Such a diagram could be superimposed upon 
a map and in nearly every case the species at the base of each 
line of development would be nearer the Texas region than 
species derived from it. 
With such an accumulation of evidence pointing to central 
Texas as the place of origin, for the section Eulesquerella at least, 
and the entire absence of evidence pointing to some other lo- 
cality as the birthplace of the genus it becomes at least possible 
to say that if this genus did not originate at this point, there is 
no evidence to show where it did appear. As for the other sections, 
it is only possible to say that there is no reason for believing they 
came into being at a different point. The first consists of a 
single species and the second of but three so that there is little 
chance for comparison here. The most primitive member of 
the second section, L. lasiocarpa, occurs in southern Texas and 
adjacent Mexico; next in order of complexity to it comes L. 
