This is the inflorescence of Bottlebrush Buckeye, Aesculus parviflora, a very nice native shrub, it measures up as a landscape plant against any summer flowering shrub. It's deciduous with the typical palmately compound leaves of an Aesculus and grows to about 10-12 feet high with a diameter a bit larger than that. It will grow nicely and flower in light conditions ranging from full sun to mostly shade. Once established, it is reasonably tolerant of drought. It does pick up the odd fungal disease, but they are rarely fatal, more usually resulting in premature defoliation. Next year's flowers are normally unaffected. It has typical Horse-Chestnut seeds minus the spikes, a good percentage of them germinate providing you with the odd plant for your own use or for distribution.
This is a plant that I first encountered in large estate gardens, it was commonly used to provide some interest and summer color along the midground of a vista viewed from the summer terrace or porch. Lately it has become commonly available in the trade. You can see nice specimens along the roadside in Fern Valley, or on the road outside the Dogwood Collection.