[Wikipedia] Soil Preferences: The species is a strict edaphic endemic of sandy soils. The soil can be derived from a diverse array of parent materials (rock types) that yield sandy textured soils, including sandstone, greywacke, chert, granite, and rhyolite (especially volcanic ash and pumice). The species favors (most common, abundant) moderately disturbed sandy soils, especially those worked by water (alluvial deposits along rivers) and wind (sand blow outs). There it occurs in sunny, open gaps between shrubs and trees. (link added by Mary Ann Machi)