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118 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, however sanely, 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 certain 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 petiolaris.

The barren and fertile flowers are usually on