118 EARLY SPRING IN MASSACHUSETTS. 
fertile catkin, is closely packed with down and 
seeds. At maturity these pods open their beaks, 
which curve back, and gradually discharge their 
burden, like the milk-weed. It would take a 
delicate gin indeed to separate these seeds from 
their cotton. 
If you lay bare any spot in our woods, how¬ 
ever sandy, as by a railroad cut, no shrub or 
tree is surer to plant itself there, sooner or 
later, than a willow ( Salix humilis , commonly) 
or a poplar. We have many kinds, but each is 
confined to its own habitat. I am not aware 
that the Salix nigra has ever strayed from the 
river’s bank. Though many of the Salix alba 
have been set along our causeways, very few 
have sprung up and maintained their ground 
elsewhere. 
The principal habitat of most of our species, 
such as love the water, is the river’s bank, and 
the adjacent river meadows, and where certain 
kinds spring up in an inland meadow where 
they were not known before I feel pretty cer¬ 
tain that they come from the river meadows. 
I have but little doubt that the seed of four of 
them that grow along the railroad causeway 
was blown from the river meadows, namely, 
Salix pedicellaris , lucida , Torreyana , and petio - 
laris . 
The barren and fertile flowers are usually on 
