96 
THE AMERICAN BOTANIST. 
Distribution of the Pipsissewa. — Our common 
pipsissewa {Chimaphila umbeUata) encircles the world in 
the north temperate zone, skipping only an occasional local- 
ity. Northward it extends nearly to the Arctic circle. Its 
relative, the spotted wintergreen {C, maculata), which, by 
the way, can hardly be properly described as spotted, is a 
strictly American plant with a much more restricted range, 
even in America. While this second species is absent from 
so much of the territor}^ inhabited by C. umbellafa, it is in- 
teresting to observe that in Japan a third species, C. Japon- 
ica, maintains much the same relation to the widespread 
species in Japan as C. manilata does here. 
Viviparous Ferns. — Several species of ferns in our 
flora occasionally bear young plants upon their fronds. The 
best known of these is the walking fern {Camptosoriis 
rhizophyllus), which normally bears a plantlet at the tip of 
each frond. A common greenhouse fern, Asplemiim bitlbi- 
ferum, produces numerous plantlets on various parts of 
the frond, and another species. Palystichum- angularc, bears 
a row of close-set plants along the main stalk or rachis. 
The latest addition to this list is the bulb-bearing cystop- 
teris {Cystopteris bulbifera), which in Vermont, recently 
developed a frond with young plants. This species is well 
known to produce bulblets from which, after they have 
fallen to the earth, young plants grow, but this seems to be 
the first recorded occurrence of young plants on the living 
frond. The specimen is figured in the October Fern Bul- 
letin. 
Introduced Weeds.— It is probable that few of us 
have anv adequate idea of the number of introduced weeds 
in our flora. In a recent lecture to the Massachusetts Horti- 
cultural S^;ciety, M. L. Fernald stated that more than 600 
species of plants have been introduced into the flora of New 
England. Tliese mtroductions have had se\'eral ways of 
