Weeds are an important source of biomass which could be utilized for biofuel production. These are undesired plants, which grow even on uncultivated land at a large scale; therefore, there is no constraint in the availability of such biomass. These are rapidly growing herbs which could provide an economically viable source of feedstock in relatively short period of time.

The harvested weed can be degraded chemically or enzymatically to release simple carbohydrates. The carbohydrates can be fermented to get bioethanol. Lantana camara, Parthenium hysterophorus, Eichhornia crassipes, and other weeds have been treated chemically and/or enzymatically to release the sugar content from lignocellulosic material. With the help of Saccharomyces cerevisiae, Escherichia coli, Klebsiella oxytoca, Zymomonas mobilis, and other microorganisms the sugars have been converted to bioethanol. The current status and future prospects of bioethanol production using feedstock derived from weeds have been discussed in this chapter in detail.