The distribution of the most common rice weeds is documented in tables and figures.

Many dominant weeds were problems already 30 years ago.

Leptochloa species seem to become increasing problem weeds in several parts of the world.

A few weeds in rice are not well defined taxonomically such as Echinochloa species and weedy rice biotypes.

The increase of rice acreages with reduced irrigation may end up in higher weed infestations and new dominant species.