A STUDY OF AUTUMN WEEDS 17 



Weed-seed collection. Take two old photographic negatives 4 by 5 or 

 5 by 7 size. Clean off the gelatin so that the glass is clear. Cut a piece 

 of thick cardboard or picture mat of the same size as the glass. With a 

 cork-cutter or auger punch out a series of five-eighth-inch holes in the card 

 with three-eighth-inch spaces between them, leaving a half-inch between 

 , the outside holes and the edges of the card. Lay this card on the clean 

 glass. Put the seeds you have collected in the holes, one kind in each, 

 printing the name of the weed from which they came below the hole. 

 Place the seeds so that those from plants in the same family may be 

 in adjacent holes, the families arranged in order. Cover with the other 

 clean glass and bind with passe-partout paper. 



Impure seed. Look up in any garden magazine or the spring numbers 

 of home magazines the addresses of some seed houses. Send for small 

 quantities of clover, grass, or some vegetable seed like cabbage or onion. 

 Look these seeds over to see if they contain any weed seed, comparing with 

 your weed-seed collection and with the more extensive collections in the 

 laboratory. What sort of seeds would be most likely to contain weed 

 seeds ? What precautions could the gardener take to make sure his seed 

 is pure ? 



Weed identification. There follows a key to the common weeds of the 

 Chicago region. Use this in finding the names of the fresh specimens of 

 your weeds until you feel sure you can identify them with certainty. 



You may work in co-operation with other members of the class, learn- 

 ;ing from them the names of weeds they have identified, but do enough 

 of the work yourself to be ready to pass a test on the use of the Key when 

 | you are given an unknown to determine. Ada M. Georgia's Manual of 

 the Weeds (Macmillan) gives descriptions and pictures of all the weeds. 

 ; (See the library copy.) Many government and state pamphlets on weeds 

 ! are to be had for the asking or at very low prices. A list of some of the 

 best of these is given in the Source Book of Biological Nature Study. 



KEY TO THE COMMON WEEDS OF THE CHICAGO REGION: References to 

 Gray's New Manual of Botany, 7th Edition. Directions: Choose the 

 first one of headings I-IX that fits the specimen you are determining. 

 Then choose between a, aa, b, bb, etc., until you reach the name of the 

 weed you have in hand. 



KEY TO THE COMMON WEEDS OF THE CHICAGO REGION 



I. Weeds with milky juice 



a Leaves with entire or nearly entire margins 

 b Leaves small, i inch or less in length 



