Polygonaceae: Knotweed Family — Chorizanthe (Spineflower)
Flowers in this family do not have separate petals and sepals. For plants like this, the term “perianth” is used to describe the flower (i.e. the calyx and the corolla together) and “perianth parts” to describe the individual elements. In spineflowers, what you mostly see are the involucres and involucral membranes. The flowers themselves are 6-lobed, usually a similar color to the involucral membranes.