When Do Maple Trees Lose Their Leaves? An Analysis of the Latest Leaf-Fall Times
The maple tree is a tall tree of the genus Acer in the family Aceraceae, reaching a height of 24 m with a crown spread of up to 16 m, and many are world-famous ornamental trees. Maple leaves are brilliantly colored and uniquely beautiful in shape, and can be made into bookmarks, specimens and so on. In autumn they turn fiery red, and when they fall to the ground they become deep red. Let us take a look below at when maple trees lose their leaves!
When do maple trees lose their leaves?
Maple leaves fall in autumn. When autumn arrives, the days shorten and the nights lengthen, the weather turns cold, the soil temperature drops, rainfall decreases, and the water-absorbing capacity of the roots is greatly weakened, while the transpiration rate does not diminish, so the lack of water causes leaf fall. At the same time, after a certain period of physiological activity, large amounts of metabolic products such as minerals accumulate in the cells of the leaves, causing the decline and death of physiological functions (destruction of chlorophyll).
Why do maple leaves turn red?
The reddening of maple leaves is in fact the result of the maple tree's response to natural stress; turning red actually acts as a sunscreen, allowing the leaves to stay on the tree longer so that the tree can absorb more nutrients. The red color of the leaves depends mainly on two substances: one is carotene, an orange-red pigment commonly present in chloroplasts, and the other is anthocyanin, which is present in the cell sap within the vacuoles. When the cell sap is alkaline, anthocyanin appears blue-purple; when the cell sap is acidic, anthocyanin appears red. After autumn begins, anthocyanin increases in the maple leaves, while the drop in temperature destroys and eliminates the chlorophyll, so the green leaves turn red.
What varieties of maple are there?
1. Truncate maple (Acer truncatum): Truncate maple, also known as Pingji maple, is a deciduous tree 8-10 m tall. The bark is grayish brown or dark brown, with deep vertical fissures. The branchlets are hairless; current-year branches are green, while perennial branches are grayish brown with round lenticels. The leaves are papery, 5-10 cm long and 8-12 cm wide. The flowers are yellow-green, polygamous, with male and bisexual flowers on the same tree, often forming hairless corymbs. The samaras are pale green when young and pale yellow or pale brown when mature. The nutlets are flattened, 1.3-1.8 cm long and 1-1.2 cm wide. The flowering period is April, and the fruiting period is August.
2. Japanese maple (Acer palmatum): Japanese maple, also known as chicken-claw maple, green maple and so on, is a small deciduous tree with dark gray bark and slender branchlets. The leaves are papery, round in outline, 7-10 cm in diameter, with a heart-shaped or nearly heart-shaped, rarely truncate base. The flowers are purple, polygamous, with male and bisexual flowers on the same tree, borne in hairless corymbs, with the common peduncle 2-3 cm long. The samaras are purplish red when young and pale brownish yellow when mature. The nutlets are spherical, 7 mm in diameter, with prominent veins. The flowering period is May, and the fruiting period is September.
3. Amur maple (Acer ginnala): Amur maple, also known as North China tea-leaf maple, is a deciduous shrub or small tree 5-6 m tall. The bark is rough, slightly vertically fissured, gray, rarely dark gray or grayish brown. The leaves are papery, with a rounded, truncate or slightly nearly heart-shaped base; the blades are oblong-ovate or oblong-elliptic, 6-10 cm long and 4-6 cm wide. The flowers are polygamous, with male and bisexual flowers on the same tree. The fruit is yellow-green or yellowish brown; the nutlets are covered with long soft hairs when young, with prominent veins, 8 mm long and 5 mm wide. The flowering period is May, and the fruiting period is October.
4. Paperbark maple (Acer griseum): Paperbark maple is a deciduous tree 10-20 m tall. The bark is ochre-brown and often peels off in oval, papery flakes. The compound leaves have 3 leaflets; the leaflets are papery, ovate, elliptic or oblong-elliptic, 5-8 cm long and 3-5 cm wide, with a bluntly pointed tip and 2-3 large blunt serrations along the margin; the terminal leaflet has a wedge-shaped or broadly wedge-shaped base and a 5-8 mm petiolule, while the lateral leaflets have oblique bases. The cymes are covered with long soft hairs and often bear only 3 flowers; the common peduncle is 6-8 mm long, and the flowers are pale yellow, polygamous, with male and bisexual flowers on separate trees. The nutlets are yellowish brown, convex, nearly ovate or spherical. The flowering period is April, and the fruiting period is September.