LACTARIAE OF THE UNITED STATES 5 
Schlesien. * And Hennings has followed Schroter in his treatment 
of the genus in the Engler & Prantl, Natürlichen Pflanzenfamilien. 
Schróter has separated Lactaria plinthogala (Otto) ї and Zac- 
taria ligniota Fr. under the generic name Гасатейа | upon the 
basis of the yellow spores. But if the spore color is taken asa 
generic character, one must include other yellow-spored Lactariae,. 
namely L. deliciosa, L. subpurpurea, and related species, as well 
as /. delicata, L. crocea, and L. trivialis, which are widely divergent 
from Z. plinthogala апа Г. Потоа. Furthermore, Г. Gerardi, а 
white-spored species, is so closely related to these two species 
as to suggest an origin from them. Hennings, also, has described 
one latex-bearing species from Africa under the generic name Lac- 
tariopsis,§ the distinctive characteristic being the presence of a mem- 
branaceous veil connecting the stem with the pileus. After a care- 
ful study of the morphological and physiological characters of the 
species forming the genus Гас?а??а as it now stands, I have come 
to the conclusion that with the exception of the tribe Реигориз Fr., 
which is not represented in America, there is not sufficient differ- 
entiation to form the basis of separation into smaller genera. Тһе 
morphological characters which might serve as generic traits are 
neither constant enough in any group nor sufficiently limited to the 
one group. Taking for example the tomentose margin, we find it 
combined with a viscid pileus іп Z. ¢orminosa (Schaeff.) Pers., and 
with a dry pileus іп Z. deceptiva Peck; while, if Г. regalis Peck 
shall prove to be a valid species or only a form of L. restma Fr., it 
will give us in either case two physiologically and naturally related 
plants, one with tomentose, the other with glabrous margin. Again, 
among the species classified by Fries under Ше Ррегай, we find 
glabrous forms like ZL. piperata (L.) Fr., and tomentose ones like 
L. vellerea Fr., yet there is no doubt but that these two are very 
closely related. In every group except the Piperatae there are 
species showing a deepening color in the mature gills, together 
with more or less pruinosity. The homogeneity of the genus is, 
%3: 534. 1880. 
t Agaricus plinthogalus Otto, Versuch Agar. 75. 1816. 
Agaricus fuliginosus Ет. Syst. Myc. 1: 73. 1821. 
Lactarius fuliginosus Ет. Epicr. 348. 1838. 
pt Schles. 3: 544. 1889. 
2 Bot. Jahrb. 30: 51. 1901. 
