142 



FARM WEEDS OF CANADA 



when there are no ray flowers it is said to be discoid. The 

 true seed is enclosed in a hard, dry shell, like a small nut, botanic- 

 ally called an achene. There are often two forms of seeds on 

 the same flower; the centre ones are generally straighter, narrower 

 and more or less angled through compression. 



The members of this large family are divided into two 

 series, according to the nature of the corolla. In the first series, 

 the Tube-flowered Composites (Tuhuliflorae), the corolla is tubular 

 and regularly 5-lobed in all the flowers which bear stamens and ' 

 pistils, and strap-shaped only in the marginal or ray flowers. In 

 the second series, the Strap-flowered Composites (Liguliflorae) , 

 the corolla is strap-shaped in all the flowers of the head. To this 

 series, also known as the Chicory family (Cichoriaceae) , the 

 Chicory and many other plants with similar flowers belong, 

 including numerous well known weeds, such as the dandelions, 

 sow thistles, lettuces and hawkweeds. The great majority of 

 the weeds in this family belong to the first series, the Tube- 

 flowered Composites. Such a large number of plants are grouped 

 under this series that it becomes necessary to subdivide them 

 into tribes. 



TRIBE VERNONIEAE 



Ironweeds (Vernonia species) are common perennial weeds 

 along roadsides and low, permanent grass lands in the southern 

 part of the eastern provinces. They are tall plants with long 

 leaves and red-purple flowers heads. They may be kept in 

 check by continued close cutting or easily destroj^ed by cultiva- 

 tion on lands that can be brought under the plow. 



TRIBE EUPATORIEAE 



Joe-Pye Weed (Ewpatoriuvi purpureum L.) grows from 4 

 to 8 feet high, without branches, 3 to 6 large smooth leaves, 

 growing in whorls at the joints, and with large clusters of pale 

 pink to whitish flowers. Common in low meadows and pastures 

 throughout Canada. It is easily destroyed by shallow cultivation. 



