Types of weed in crop field

 There are different types of weed in crop field. Based on the morphological feature weeds are three  different types.

True grasses : Grasses are the plant of poaceae family. These have simple small thin leaves with parallel vein.  Crabgrass, fox tail

Seedge : These are not true grass. These are different from grass that these have triangular stem.  Examples,  nutseedge,  purple nutseedge and bulrush. 

 Broadleaf weeds : Broadleafs are different from all other two weed. These have wide leaf. Among the weeds clover give benefit to soil by nitrogen fixation. 

According to the plant life cycle the weeds are in three classes 

Annual weeds: Weed life cycle within one year. Example,  crabgrass and pigweed. These plant grows in summer and germinate in spring.

Chickweed and henbit is a winter annual weed that germinate in fall summer, grows in spring and survive in winter.

Binneal weed : Weeds life cycle within two years. These have two types of growth. First year growth is vegetative growth like forming body and root, storing energy and in second year flowering and fruiting. The examples are wild carrot,  bul thistle, burdock.

Perennial weed : Weeds life cycle more than two years. Examples dendalion, Canada thistle, Bermuda grass.

These may have two types of reproduction. Vegetative reproduction and seed reproduction. Dendalion and plantain spreads through seed but Bermuda grass spread with rhizome. This is a creeping plant else.