Redwood is a native, evergreen, long-lived (greater than 2,200 years), monoecious tree [38,40] (monoecious = "having reproductive organs typical of both sexes in a single individual"). Redwoods are among the world's tallest trees; trees over 200 feet (61 m) are common, and many are over 300 feet (91 m) . The largest tree thus far was measured at 364 feet (110.3 m) in height and 20 feet (6.1 m) in d.b.h. ("diameter at breast height") . The root system is composed of deep, widespreading lateral roots with no taproot [40,44]. The bark is up to 12 inches (30 cm) thick and quite fibrous . Redwood self-prunes well in dense stands ; the base of the bole is strongly buttressed .
Redwood is endemic to the coastal area of northern California and southwestern Oregon. The redwoods occupy a narrow strip of land approximately 450 miles (724 km) in length and 5 to 35 miles (8-56 km) in width. The northern boundary of its range is marked by two groves on the Chetco River in the Siskiyou Mountains within 15 miles (25 km) of the California-Oregon border [22,40]. The southern boundary of redwood's range is marked by a grove in Salmon Creek Canyon in the Santa Lucia Mountains of southern Monterey County, California .
Redwood occurs in a maritime Mediterranean climate, where the winters are cool and rainy, and the summers are dry. The mean precipitation is 70 inches (180 cm), with 90 percent falling between October and May. The dry summers are mitigated by a heavy fog belt . The fog reduces the drought stress of this hydrophilic plant by reducing evapotranspiration and adding soil moisture. Redwoods beyond the fog belt appear to be limited to areas of high moisture. Currently there is considerable debate over the link between the fog belt and redwood distribution .