Acer shirasawanum aka Shirasawa's Maple

Acer shirasawanum, also known as the Shirasawa maple or fullmoon maple, is a species of maple native to Japan. It can be found in central and southern Honshū, Shikoku, and Kyūshū. This deciduous large shrub or small tree typically reaches heights of 8-15 meters with a smooth bark. Its palmate leaves have sharply-toothed lobes that start off bright red when young, then transition to a fresh yellow-green color as they mature. In autumn, the foliage transforms into shades of orange and red. The shoots of Acer shirasawanum are slender and hairless. The rounded leaves are 4.5-8 cm long and 6-12 cm broad, with 9-13 serrate shallowly incised lobes. Initially, they may have thin white hairs but become hairless over time. The petiole is 3-7 cm long and also hairless. The flowers, which appear in early spring after the leaves, are 1 cm in diameter and have dark purplish-red sepals, small whitish petals, and red stamens. The species is andromonoecious, meaning it produces inflorescences containing flowers with both sexes or just male. The fruit consists of paired samaras with nutlets that are 5-10 mm in diameter and have a 20-25 mm wing. They stand erect above the leaves and initially appear bright red, maturing to brown. Acer shirasawanum is named after Japanese botanist Homi Shirasawa. It can be distinguished from Acer japonicum and Acer sieboldianum by its hairless shoots. Some authorities still classify it as Acer japonicum, leading to mislabeling in cultivation. Acer shirasawanum is primarily grown as an ornamental tree for its attractive foliage and autumn colors. The cultivar 'Aureum' is particularly popular and has received the Royal Horticultural Society's Award of Garden Merit. Propagation is commonly done through grafting onto hardier and faster-growing Acer species such as Acer palmatum and Acer japonicum.