Initial effects of ashfall from mount st. Helens on vegetation in eastern washington and adjacent idaho.

Extensive plant damage from the 18 May 1980 eruption of Mount St. Helens was largely restricted to acaulescent andprostrate dicot species in the ashfall area east of the Cascade Range (more than 150 kilometersfrom the vent). Veratrum californicum, a large monocot, displayed widespread stem death through mechanical overloading of the plant's clasping leaves. The ash surface in this area presents new opportunities for both seeds and seed predators.