It's named for Marion County in the Willamette Valley, where most of the field trials took place. When the berry was introduced in the 1950s, it was widely hailed as the most delicious blackberry commercial cultivar around. Even today, people rave over its tart-yet-sweet flavor, described as a cross between raspberries and blackberries. (Though there is some raspberry in its DNA, the red fruits are more like a genetic great-great grandparent to the marionberry.) Ecology The Willamette Valley is prone to periodic floods. Notable floods include the Great Flood of 1862, events in 1899, the Christmas flood of 1964, the Willamette Valley Flood of 1996, and the Willamette Flood of 2019. Part of its floodplain is a National Natural Landmark called the Willamette Floodplain. Historically, the Willamette Valley forests were mostly an oak savanna—tall grasslands with scattered Garry oaks and groves of coast Douglas-fir. The river floodplains contained extensive wetlands, stands of willow, alder, and cottonwood, and gallery forests. This landscape was maintained by the Native American inhabitants of the valley who set frequent fires that encouraged the open grasslands and killed young trees. The American settlers of the region, since the 19th century, suppressed fires and converted much of the valley to agriculture, which has caused much of the former grassland and savanna to revert to closed-canopy forest. Less than one-tenth of one percent of the original savanna vegetation remains. The remaining enclaves include a section of Garry oak savanna preserved at Mount Pisgah Arboretum in Eugene. North Pacific Oak Woodland is a major forest alliance, extending through the Willamette Valley and southward to the Klamath Range of Northern California. Many of the soils are well-drained mesic. Human history Human habitation in the Willamette Valley is estimated to have begun between 6,000 and 10,000 years ago. Until recently, the valley was largely inhabited by bands of the Kalapuya tribe of Native Americans. Molala and Chinook peoples also have inhabited portions of the Willamette Valley since time immemorial. Sixteen thousand Kalapuyans are estimated to have populated the valley as recently as the early 19th century. As many as 90% of the Kalapuya may have died as a result of an epidemic of "fever and ague" that hit the area between 1830 and 1833. Salmon, deer and camas bulbs have provided primary food sources for the valley's first residents who used fire to encourage persistence of oak savanna. Oak trees have