v1 
Some of the more important introduced species not noted by Prof. 
Tuckerman, which are more or less common now, are Trifolium hy- 
bridum L., golden hawkweed, Bromus tectorum L., Russian thistle 
(Salsola), Galinsoga, Berteroa incana (L.) DC., Thymus Serpyllum L., 
Cynodon Dactylon (L.) Pers., Lysimachia Nummularia L., Lychnis 
Flos-cuculi L. and Lychnis alba Mill. 
Impure seed is the most important factor in the introduction of 
harmless and noxious species, and from 75 to 100 or more different 
species may occur ina particular sample or lot of grass seed. The 
impurities run from 5 to 25 per cent or more, and although frequently 
harmless, 10 or 15 per cent of noxious weeds are sometimes present in 
grass or clover seed. Since seed are sent from all over the United. 
States and imported from foreign countries, it follows that a great 
variety of-plants may be introduced into a particular region. Black 
medick, Canada thistle, charlock, chicory, crabgrass, chickweed, dod- 
der, various docks and plantains, green foxtail, goosefoot, lady’s 
thumb, ragweed, sheep sorrel, wild carrot, witch grass, yellow foxtail 
and many others constitute the principal impurities in seed. Dame 
and Collins,! in their “ Flora of Middlesex county,” enumerate 460 
naturalized and adventive species and varieties which have become 
more or less established in that region. 
In the preparation of this list Iam under obligations to different 
ones whose names will be found throughout the text. This is espec- 
ially true of Mr. Ray E. Torrey, of the 1912 class of this College, who 
has rendered valuable assistance all through the work. Mr. Torrey 
has also been of great service, from his extensive collecting and criti- 
cal knowledge of our flora, in furnishing data in regard to the present 
range of certain species. 
I am also indebted to Prof. A. Vincent Osmun, my colleague, who 
has given much attention to our native ferns and violets, and to Miss 
Jessie V. Crocker for assistance in seeing the work through the press. 
Dr. W. H. Chapin, of Springfield, has kindly furnished notes in regard 
to the plants in that locality, and Mrs. Maria L. Owen’s long experi- 
ence in collecting and studying the native plants has been helpful. 
Mr. Luman Andrews, of Southington, Connecticut, who is at present 
making an exhaustive study of the plants about Springfield, has fur- 
nished a large amount of data concerning new finds, as well as extend- 
ing our knowledge of the range of other species. Mr. Andrews’ her- 
barium has been presented to the Springfield Science Museum, where 
it is well arranged, and it is anticipated that he will add greatly to it 
in the future. We have also had access to the herbarium of the 
Springfield Science Museum, which besides the already referred to 
Luman Andrews collection, contains that of the Springfield Botanical 
1 L. Dame and F. S. Collins, ‘‘ Flora of Middlesex County, Massachusetts, 1888. 
