302 OHIO EXPERIMENT STATION: BULLETIN 175. 



the resemblance to some plant illustrated or known, will assist 

 according- to the circumstances. The resemblance of a given 

 plant to some one of a known family will aid greatly in the use 

 of the indexes. The annual (A) biennial (B) and perennial (P) 

 weeds are distinguished. The technical names of weeds intro- 

 duced from beyond our borders are designated by an asterisk. (*) 



DESCRIPTION AND ILLUSTRATION OF WEED SEEDS. 



An effort has been made to describe and illustrate the weed 

 seeds likely to be met with in commercial seeds and forage. The 

 descriptions are given in popular language and with as much exact- 

 ness as has seemed possible; in nearly all cases they were made 

 from specimens, the remainder are based on Nobbe's illustrations. 

 The descriptions will no doubt be found to be of unequal value and 

 frequently quite inadequate. The only magnifier employed was a 

 Coddington lens Y? inch focus, such as is illustrated in Fig. 1. A good 

 deal has been accomplished in seed illustrations since the issue of 

 the first manual in 1897. We have endeavored to profit by these 

 contributions in the present issue. Where new cuts were made the 

 illustration of seeds was included. The illustrations of weed seeds 

 reproduced by photography are printed in plates at the back of the 

 bulletin. 



SOURCES OF INFORMATION. 



The list is based upon the material accumulated from corres- 

 pondence during- the past ten years, including the many cordial 

 responses to requests for lists of roadside weeds, and upon the 

 results of personal investigations. The contributed roadside weed 

 lists, given in the tables at the end of the former bulletin, are 

 omitted in this issue. It has appeared best to base estimates of a 

 goodly number of weeds quite largely on the known botanical 

 characters of the plants in question. An occasional patch of toad- 

 flax or of bouncing-bet, or a cemetery over-run in parts with cypress 

 spurge and periwinkle, commonly excites little apprehension until 

 it is too late; the true characters of these plants and a host of 

 others are not reailzed. Likewise the frequency of certain weed 

 seeds in commercial seeds and hay may appear at times to be 

 stated in strong terms; but these statements are based upon the 

 results of examinations made at the Station. It may be admitted 

 that correspondents are more likely to send impure seeds than clean 

 seed without altering greatly the state of the question. The 

 responsibility must finally be laid where it belongs. 



