CALIFORNIA LILAC (Ceanothus thyrsiflorus), a name given to a handsome North American tree of the buckthorn family (Rhamnaceae), called also blue blossom and blue myrtle. It grows on canyon sides from Monterey northward to Oregon and is especially abundant in the redwood belt. While usually a shrub, 3 ft. to 8 ft. high, it sometimes becomes a small tree 25 ft. in height with straight ascending branches. The small, smooth, oval or oblong leaves are green on both sides and shining above, with the edges minutely toothed. The showy blue or rarely white flowers are borne in dense clusters about 3 in. long. (See CEANOTHUS ; NEW JERSEY TEA ; OREGON TEA-TREE.)