Ceanothus thyrsiflorus

Ceanothus thyrsiflorus, known as blueblossom or blue blossom ceanothus, is an evergreen shrub in the buckthorn family Rhamnaceae that is endemic to Oregon and California in the US. The term 'Californian lilac' is also applied to this and other varieties of ceanothus, though it is not closely related to Syringa, the true lilac.

Description
Ceanothus thyrsiflorus can grow more than 6 m tall and broad in its native chaparral habitat, with glossy green leaves. The clusters of tiny flowers, borne in spring, vary from different shades of blue to close to white. The evergreen leaves are shiny and about 4 cm long.

Etymology
The Latin genus name Ceanothus is derived from the Ancient Greek, keanothos (κεάνωθος; 'spiny plant'). The name was originally used by Theophrastus for another plant, and Linnaeus reused it for Ceanothus.

The Latin specific epithet thyrsiflorus is derived from the Ancient Greek thyrsos (θύρσος; meaning a 'contracted panicle, wreath, or thyrsos') and the Latin florum ( gen. 'flower'), and so, thyrsiflorus means approximately 'with flowers arranged in the shape of a contracted panicle or thyrsos staff'.

Ecology
It is popular with birds, butterflies, and other pollinators. It is often visited by honeybees for its pollen.

Cultivation
Ceanothus thyrsiflorus has been used in gardens extensively. It prefers a warm, sheltered position in full sun. Several cultivars have been selected, including:
 * 'Blue Mound' which can grow to 1.5 m tall
 * 'Cascade' which may reach 8 m of height
 * 'El Dorado', a variegated cultivar with gold edge foliage and powder blue flowers
 * 'Repens' which stays as a shrub around 1 - 3 m tall
 * 'Repens Victoria', forming a sturdy evergreen mound and most useful groundcover with powder blue flowers
 * 'Skylark', a tall type with blue flowers (this cultivar has gained the Royal Horticultural Society's Award of Garden Merit)
 * 'Snow Flurry', with white flowers