http://www.calflora.org/app/ipl?vrid=gr5120 Big list andpics of griffith plants
Perhaps the most obvious are trees in the Eucalyptus genus. Although they can be graceful in appearance and often smell good, they are highly destructive of native plants due to a combination of shading, leaf and bark ground litter, and a soil-poisoning property known as allelopathy.
Often seen in areas that have been disturbed, such as along roadways, are castor (Rícinus commùnis), an extremely poisonous bean; tree tobacco (Nicotiàna gláuca) with grayish green leaves and yellow, tubular-shaped flowers; and the ubiquitous black mustard (Brásica nìgra) with pale yellow flowers.
In areas with more shade or damper soil, poison hemlock (Conìum maculàtum) with its tall, straight stocks and clustered white flower umbels is common, as is eupatory or white snakeroot (Ageratìna adenóphora), also with white flower clusters.
Also common throughout is horehound (Marrùbium vulgàre). Yellow starthistle (Centáurea meliténsis) is particularly annoying, growing along trail sides.
The exotic genie is out of the bottle, and there is no way to completely return to the way things were. Some of us will continue to try, however. Those interested in helping should contact the California