The word savanna entered New World English in the sixteenth century by way of the Spanish, who had taken it from a Caribe term for meadow. And the diverse savannas of North America—whether pine savannas of the Southeast, oak savannas of the Midwest, ponderosa savannas of the Rockies, or juniper-piñón savannas of the Southwest— are all grassy, meadowlike landscapes, intermediate between treeless plains and closed-canopy woodlands. The savanna overstory is broken, patchy. Trees cover only about a third of the land and grow singly or in copses. The understory is composed largely of tall grasses, sedges, and wildﬂowers. Historically, North American savannas were maintained by frequent ﬁres, either naturally occurring or set by Native Americans to control undergrowth and encourage grassy openings to improve habitat for the grazing animals they hunted. But savanna ecosystems have become increasingly threatened and rare as a result of ﬁre suppression and clearing for commercial pine plantations, agriculture, and development. In the Southeast, for example, almost nothing remains of the old-growth longleaf pine savannas that once dominated the landscape of the coastal plain.