SOME RECENTLY INTRODUCED WEEDS. 



BY MERRITT L. FERXALD, CAMBRIDGE, MASS. 



Delivered before the Society, January 14, 1905. 



The clearing of the forest lands and the letting in of the 

 direct sunlight is the inevitable forerunner of the farm and the 

 village, but it is as inevitably the death warrant of hundreds of 

 native plants. As is now well vxnderstood, a majority of our 

 woodland species have a root structure which allows them to 

 grow only in the moist, spongy humus of the forest or the 

 swamp, conditions, as many of us know from practical experi- 

 ence, almost impossible of artificial attainment. Try as we will 

 most if not all of us have failed to imitate with sufficient skill 

 permanently to satisfy the plant the exact conditions which 

 please the stemless lady's slipper {Cyprijyedium acaule), the 

 trailing arbutus {Epiijaeci)^ the various species of Pyrola, the 

 yellow wild foxgloves {Gerardia)^ the painted cups (Castilleja), 

 or the fringed gentian ; though in their undisturbed haunts these 

 plants bloom regularly and reproduce freely. 



In their own wild homes, likewise, these and scores of other 

 species are almost as sensitive to change as when forced by man 

 into an unappreciated state of culture. The simple cutting of 

 the forest is to most of these plants disastrous, though such of 

 them as are very hardy will often Hnger until fire has swept the 

 cleared land and burned out the tmdei'-like humus. After the 

 fire comes a complete change of vegetation, and, during the 

 interval before the stumps are finally removed and the land 

 turned by the plow, the clearing too often becomes a tangle of 

 fire cherry (Primus 2)emisi/loanica), aspens (Populits tremu- 

 loides and grandidentata)^ and other quick-growing trees and 

 shrubs with a liberal mixture of blackberry and raspberry bushes, 

 fireweeds {Epilohiwn and Erechtites), rattlesnake- weeds {Pre- 

 nanthes), and other coarse plants which love the open and the 

 direct sunshine. When the final planting of the farm crop 



