THE AMERICAN BOTANIST. 
entrance. Some have come by way of the railway; others 
as ballast in ships from foreign ports, while still others ar- 
rived among seeds for field and garden, clinging to the coats 
of domestic animals, etc. Along one river in Connecticut 
the origin of great numbers of new weeds was traced to a 
rubber factory using old rubber shoes. In the linings of 
these shoes, which were thrown out, great numbers of weed 
seeds were hidden. We have sent few weeds to the Old 
World to balance accounts, but occasionally something is 
done to make the scores nearer even. Ovir common ditch 
moss (Elodea), which at home is a mild and inoffensive 
plant, has completely choked up many British streams and 
become a fair offset to the damage done by^ the water-cress 
(Nasturtium) in this countr>\ 
Habitat of the Lady's Slipper.— There are many 
curious things about the orchids besides their flowers and 
methods of pollination. It has been pretty well settled that 
some species may rest for a year or m<jre without showing 
a sign of foliage above ground. Another interesting cir- 
cumstance connected with these plants is the habitats selected 
by them. In some regions the pink lady's-slipper (Cypri- 
pedimn acaule) is found only in swamps in the shade of 
hemlocks and ^)ther conifers : in others the plants grow on 
dn-ish hillsides. In the last-named localities the plants seem 
to delight in a moldering log, and are usually found in col- 
onies along it. After the log has entirely disappeared one 
may often decide in which direction it extended, by the 
arrangement of the orchid coloTiy. The yellow lady's-slip- 
pers (C. pubescens and C. pan-konim) are usually found 
on dryish hillsides, but they, too. may occasionally inhabit 
the swamps. The yellow species will' thrive under cultiva- 
tion, but the pink one usually dies after a year or two, which 
fact, taken in connection with its preference for old logs, 
seems to indicate that it is a partial saprophyte. 
