adansonia gregorii Australian baobab Australian boab barrel trunk boab boab tree bottle tree brown-gray brown-grey dead rat tree deciduous distinctive gadawon gouty stem tree grotesque indigenous Kimberley native large road verge shape slow-growing smooth bark soft fibrous wood trunk useful verge water retention adansonia-gregorii Australian-baobab Australian-boab barrel-trunk boab-tree bottle-tree dead-rat-tree gouty-stem-tree Kimberley-native smooth-bark soft-fibrous-wood surface surfaces texture textures water-retention cream flower flowers fruit furry nut white damage damaged diseased pitted recovery repairing self-repairing wounded wounds