Herbaceous perennial or biennial, with rigid, wiry flowering stems to 1 m tall, milky sap . Plants exist as basal rosettes until flowering stems develop at maturity and rosette leaves whither. Persistent flower stems can hinder harvest machinery.
Plants are highly competitive for water and nutrients.
Rush skeletonweed is also a significant problem in several other countries, particularly Australia. Introduced from southern Europe. All are established in California. First leaves elliptic with backwards pointing teeth. Require a continuous moisture supply for up to 6 weeks to develop a persistent root system.