1922] SEARS—TARAXACUM 433 
MazetTI, already quoted. As to details of achene form, it is 
possible to find in a field of T. vulgare and T. laevigatum achenes 
varying from nearly smooth to almost shaggy. Asa rule the form 
seems consistent in the individual plant. 
FLOwErRS.—Color is markedly influenced by pigmentation of 
styles as well as of petals, and by presence or absence of ripe pollen. 
That flower number per head may not always be relied upon as a 
criterion becomes evident from field studies. Depauperate plants 
whose species is unquestionable may produce a surprisingly small 
number, as few as fifty. 
PoLLEN.—In the spring of 1921 at Lincoln, Nebraska, pollen- 
less plants, both red and gray fruited, were found, the former in 
abundance. Microscopic examination showed that pollen develop- 
ment had been arrested before the grains had separated. Certain 
interesting correlations were noted in the red fruited pollenless 
forms. The leaves are invariably dissected less than the maximum 
for T. laevigatum, and the inner bracts are twelve or thirteen in 
number, containing in all eighteen to twenty-two corniculi on their 
greenish tips. It was at first believed that this represents a distinct 
genetic type, and such indeed may be the case. Search revealed a 
number of transitional forms, however, with scant pollen, fifteen 
to eighteen reddish bracts, and leaves considerably dissected. T. 
laevigatum itself has copious pollen, eighteen to twenty red tipped 
bracts each bearing a corniculus, and leaves heavily dissected. 
In one case a combination of the two extremes was obtained on 
different rosettes of the same old root. Quantitative studies, 
quoted by the courtesy of Mr. H. PEGLerR, show that the degree 
of leaf dissection in the pollenless forms increases as one passes 
from peripheral to central leaves, and lies exactly between the 
increasing dissection of a young seedling of T. /aevigatwm and the 
fluctuating dissection of a typical adult of the same species. It 
is not unlikely, therefore, that this is even a more interesting 
case of isolation of pseudotype than is the 7. palustre form of 
T. vulgare. 
Bracts.—Aside from the case just described, bracts of both 
species have been found to vary notably in the degree of develop- 
ment of the corniculi, in number between twelve and twenty-two, 
and in color. 
