Importance of Weeds with Examples

Importance	Examples
Maintain soil fertility	Typha spp. (adds 1–35% nitrogen)
Control soil erosion	Cynodon dactylon, Convolvulus arvensis
Used as fodder	Cichorium intybus, Cynodon spp.
Have medicinal value	Leucas aspera – used in snake bite
	Striga spp. – used in diabetes
	Phyllanthus niruri – used in jaundice
	Argemone mexicana – used in skin disease
Have economical value	Roots of Cichorium intybus – used to add flavour to coffee
	Cyperus rotundus – used in making agarbatti
	Saccharum spontaneum – used for roof making
Maintain soil pH	Argemone mexicana – converts alkaline soil to acidic
	Rumex acetocella – converts acidic soil to alkaline
Used as ornamental plants	Lantana camara, Eichhornia crassipes
Used in cleaning water	Eichhornia crassipes
Adds organic matter to soil	Amaranthus viridis, Convolvulus arvensis
Used as vegetables	Chenopodium album, Amaranthus viridis
Religious purpose	Cynodon spp.
Useful for cottage industries	Saccharum spontaneum, Typha spp.
Donating genes to crop plants (crop breeding)	Saccharum spontaneum (used in sugarcane)
Used as nematicides	Crotolaria spp., Parthenium
Used as pollution indicator	Brassica kaber (wild mustard) – indicates NO₂ pollution
	Stellaria media (chickweed) – indicates SO₂ pollution