Dear Friends, this ten-petal mentzelia is growing out of the red rock in the Theodore Roosevelt National Park, locally the red rock is called scoria, but the real term is porcelainite (sp) , made from clay layers being baked by a burning coal layer, if you drop a piece on a hard surface it will ring like a china cup, hence another local name, clinker.   the white flower of the mentzelia is only present in late summer near sundown and before sunrise.   til Tomorrow MJ