DESCRIPTIVE MANUAL 



221 



Fig. 127-C. Distribution of Common Mallow. 



Shoo-fly {Hibiscus trionum L.). 



Description. — A low, rather hairy annual from 1-2 ft. high ; upper 

 leaves 3-parted with 3 lanceolate divisions, the middle longest ; calyx 

 inflated in fruit, membranous, 5-winged, with numerous dark 

 nerves ; flowers sulphur-yellow with a blackish eye, ephemeral. 



Distribution. — Common in fields and waste grounds in the south- 

 ern states and eastward ; abundant in some places in Iowa, especially 

 in gardens where it has become naturalized from cultivation. 



Extermination. — A growing plant is not difficult to exterminate. 

 A thorough cultivation and exposing the roots to the sun will de- 

 stroy the plant. The seeds, however, retain their vitality for a con- 

 siderable length of time. A correspondent of southeastern Iowa 

 stated that this weed kept coming up in spite of constant and thor- 

 ough cultivation. This was owing to the prolonged vitality of the 

 seed. 



HYPERICACEAE. ST. JOHN'S-WORT FAMILY. 



This small family contains a few ornamental plants with yellow 

 flowers, commonly found in northern states. 



