Leafing out in spring with a bright red, becoming more dark red or maroon in summer. Fall colour is bright red. Acer palmatum 'Twombley's Red Sentinel' is a perfect tree for a small, narrow space in your yard. It will grow to about 8-10' tall and 3-4' wide in about fifteen years. Eventually, this tree may be up to 20' tall and 6-8' wide so, still maintaining a very columnar shape.