The white or creamy coloured flowers,[4] occurring May to June, are numerous and form a flat-topped cluster usually about 5–20 cm (2–8 in) wide.

They are bluish-black, with a glaucous powder coating lending them a light blue colour[4] (and helping distinguish them from other elderberries).

Both the current United States Department of Agriculture database and The Jepson Manual of California flora (2013) classify it as S. nigra subsp.

[5][6] The botanist Victor King Chesnut (1867–1938) had classified it as S. glauca in 1902, when studying the plants used by the Indigenous peoples of California in Mendocino County.

[1][2] This species grows at elevations below 3,000 m (9,800 ft), in diverse habitats of mountains and hills, valleys, riparian zones, open places in woodlands and forests, and exposed slopes where moisture is reachable.

[9] The indigenous peoples of North America with the plant in their homelands use the leaves, blossoms, bark, roots, and wood for preparing traditional medicinal remedies, taken internally or applied externally.

[10] Some tribes used the wood to make musical instruments, such as flutes, clappers, and small whistles;[a] and smoking implements.

[5] The plant is beneficial in wildlife gardens, its flowers attract pollinators, butterflies and hummingbirds, and its berries feed other bird species and chipmunks.