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 tectormn 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 in a 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 no-xious 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 Ust I am under obKgations 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 



L. Dame and F. S. CnUins, " Flora of Middlesex Cniinty, Massachusetts, 18 



