When do maple leaves generally turn red and fall, and when do new leaves grow, and what are the main ornamental varieties?

Maple flowering period is April to May, leaf-fall period is September to October, and new leaves generally grow in March of the following year. In autumn, maple leaves gradually turn red or yellow, and also green and purple, making it a famous autumn foliage tree species. Among the many maples, the eight main varieties with ornamental value and representativeness are Acer truncatum, Acer palmatum, Acer ginnala, Acer griseum, Acer henryi, Acer laevigatum, Acer crassum, and Acer olivaceum.

1. Acer truncatum

Also known as Acer truncatum Bunge, 8-10 m tall. Bark grayish brown or dark brown, deeply longitudinally fissured. Branchlets hairless, current-year branches green, perennial branches grayish brown, with circular lenticels. Winter buds small, ovate; scales acute, outer side slightly pubescent. Flowering period April, fruiting period August.

Mainly produced in Jilin, Liaoning, Inner Mongolia, Hebei, Shanxi, Shandong, northern Jiangsu (areas north of Xuzhou), Henan, Shaanxi, and Gansu provinces and regions. Grows in open forests at an altitude of 400-1000 m.

2. Acer palmatum

Also known as: Japanese maple, green maple. Bark dark gray. Branchlets slender; current-year branches purple or pale purple-green; perennial branches pale gray-purple or dark purple. Flowering period May, fruiting period September.

Mainly produced in Shandong, southern Henan, Jiangsu, Zhejiang, Hunan, Hubei, Anhui, Jiangxi, Guizhou and other provinces. Grows at forest edges or in open forests at an altitude of 200-1200 m. Also distributed in Korea and Japan.

3. Acer ginnala

Also known as: North China tea maple, 5-6 m tall. Bark rough, slightly longitudinally fissured, gray, rarely dark gray or grayish brown. Branchlets slender, nearly cylindrical, hairless, current-year branches green or purple-green, perennial branches pale yellow or yellowish brown, lenticels elliptical or nearly circular, pale white. Winter buds small, pale brown, 8 scales, with long soft hairs near the margin, imbricate. Flowering period May, fruiting period October.

Mainly produced in Heilongjiang, Jilin, Liaoning, Inner Mongolia, Hebei, Shanxi, Henan, Shaanxi, Gansu. Grows in thickets below an altitude of 800 m. Also distributed in Mongolia, eastern Siberia of the Soviet Union, Korea and Japan.

4. Acer griseum

10-20 m tall. Bark ochre-brown, often ovate, papery thin flakes peeling off. Branchlets cylindrical, current-year branches pale purple, densely covered with pale yellow long soft hairs, perennial branches dark purple or dark brown, branches 2-3 years old still retaining soft hairs. Flowering period April, fruiting period September.

Mainly produced in southwestern Henan, southern Shaanxi, southeastern Gansu, western Hubei and eastern Sichuan. Grows in open forests at an altitude of 1500-2000 m.

5. Acer henryi

About 10 m tall. Bark light brown. Branchlets cylindrical, current-year young branches purple-green, with short soft hairs, perennial old branches light brown, hairless. Winter buds small, 2 scales, ovate, brown, valvate. Flowering period April, fruiting period September.

Mainly produced in southern Shanxi, Henan, Shaanxi, Gansu, Jiangsu, Zhejiang, Anhui, Hubei, Hunan, Sichuan, Guizhou. Grows in open forests at an altitude of 500-1500 m. The type specimen was collected from Jianshi, Hubei.

6. Acer laevigatum

Also called long-leaved maple, usually 10 m tall, rarely up to 15 m. Branchlets slender, hairless; current-year branches green or pale purple-green; perennial branches pale brown-green or dark green. Flowering period April, fruiting period August-September.

Mainly produced in southern Shaanxi, western Hubei, Sichuan, Guizhou and Yunnan. Grows in relatively moist stream sides or valley forests at an altitude of 1000-2000 m. Also distributed in Nepal, Sikkim, northern India and Myanmar.

7. Acer crassum

10-12 m tall. Bark dark brown, rough. Branchlets cylindrical, hairless, current-year branches purple-green, with long elliptical lenticels, perennial branches grayish black or grayish brown. Winter buds ovate or ovate-conical, scales numerous, yellowish brown, triangular obtuse-acute, outer side hairless, margin ciliate. Flowering period late April, fruiting period September.

Mainly produced in southeastern Yunnan. Grows in broad-leaved forests at an altitude of 1000 m.

8. Acer olivaceum

5-10 m tall. Bark rough, purple-green or light brown. Branchlets nearly cylindrical, purple or purple-green, hairless, current-year branches 1-1.5 mm in diameter. Flowering period late April, fruiting period September.

Mainly produced in Zhejiang, southern Anhui and eastern Jiangxi. Grows in open forests at an altitude of 200-1000 m.