White Alder Flower

 Or Cuban Buttercup or Turnera subulata.  This pretty little flower opens in the morning and tends to close in the hot afternoon sun. Its cousin, the yellow turnera, or Yellow Alder Flower, or Turnera ulmifolia, seems to leave its flowers open for longer during the day.

(Yellow Alder Flower photo courtesy UpstateNYer, via Wikimedia Commons)

But I can't help it.  I love the little face of the white flower.  This charming Zone 9 perennial grow to about 2' in height and is native to the West Indies and Brazil.  The yellow ones, especially, can be invasive in climates like South Florida or Hawaii, but here in Zone 9A, they should eventually freeze back.  Both varieties root easily from cuttings and are normally available at independent nurseries in the summer.