Wildflowers have adapted to the arid climate at Petrified Forest National Park in many different ways. Thick, waxy coverings on leaves and stems reduce evaporation. Small leaves reduce the effects of solar radiation and water loss. Deep taproots reach far into the soil to find water while shallow, widespread roots catch and absorb surface water quickly. Despite these adaptations, wildflowers avoid drought and heat by hiding in the soil as seeds or bulbs, sometimes for decades. Germination only occurs after significant seasonal rainfall. Not all wildflowers bloom during the day. Some take advantage of cooler night temperatures to open their flowers. These evening-blooming plants include evening primrose, sacred datura, sand verbena and yucca. The yucca and the yucca moth have a fascinating dependency on one another which includes trysts in the night. After mating, the female moth gathers pollen from a yucca flower and packs it into a ball.
She then flies into the night until locating another yucca flower. Here she lays eggs in the base of the flower's pistil and packs pollen from her pollen ball down into the pistil, providing food for her young when they hatch. She visits several flowers during the night, each time distributing the pollen from flower to flower. Thus she fertilizes the yucca flowers while ensuring that her young will have nutrients to live on. Yucca plants and moths have a symbiotic relationship: yucca flowers are only pollinated by yucca moths and yucca moth larvae only feed on yucca pollen. April and May, following winter snow and rain, are generally the best months to see wildflowers throughout the Southwest. Beginning in late August, if the summer monsoon season (July-August) has brought significant rainfall, different species bloom and color the landscape once again.