In Ky. this largely midwestern species is restricted to calcareous soils, but occurs in varied kinds of woods, from damp to dry; on slopes it is usually associated with warmer aspects. Without its distinctive white flowers, albidum cannot be easily distinguished from americanum (F, Cr, FNA 26, W). Its fruits tend to be more rounded, slightly apiculate or slightly depressed at summit (versus truncate or apiculate); leaves tend to be narrower (mostly 1.5-4 cm versus 2-5 cm), often in extensive non-flowering patches; 2n = 44 (versus 48). A few days before flowers, leaves appear about two weeks earlier than americanum, on average. Flowers occasionally open as early as late Feb, but usually in mid-Mar (especially recent years) to mid-Apr; at least one to two weeks later, americanum usually flowers in late March to late April.