It has snowed in the north, but for people in the south, it is just the right time to see the yellow leaves.

A few days ago, thick snow fell in the north. What should I do if I don’t have snow to see in the south? Don’t envy the heavy snow, now is the best time to see yellow leaves in the south!

Look up and see this colorful scene｜http://tlpg.hsiliu.org.tw/

What are the yellow leaves in the south?

Compared with the north, the south is prone to rain in autumn and winter, and it is cold and humid, and the temperature difference between day and night is not large, so it is not easy to form a large area of ​​colorful leaves . But if the weather is good, some places will also show good colorful leaves.

Generally speaking, common native tree species with better color-changing effects include Chinese tallow tree, liquidambar, Pistacia chinensis, wild sumac, euonymus, red maple, golden pine, sycamore, soapberry, nandina domestica, metasequoia, etc. Among the plants introduced from abroad, the ones with good color leaves mainly include baldcypress and its closely related pond cypress, as well as some foreign species in the genus Acer, such as red maple, Norway maple, and Japanese fan maple.

Chinese tallow tree

The leaves of the Chinese tallow tree are regular diamond-shaped , which is quite unique among plant leaf shapes, so it is also a very easy-to-recognize tree species. In autumn, the Chinese tallow tree often turns bright orange-red . When planted in groups by the lake or on the grass, it often creates an ornamental effect similar to that of a red maple.

Zhangzhugang / Wikipedia

Because it is often planted by water in the South, some people speculate that the "Jiang Feng" in the poem "The moon sets, the crows cry, and the sky is full of frost. The river maples and fishing fires are opposite me, making me sleep in sorrow" is most likely Tung oil tree.

myu-myu/Flickr

Liquidambar

Liquidambar formosana is a common native plant in the South. The plant is usually tall, with palm-shaped three-lobed leaves , and two adjacent leaves are alternate on the branches.

TANAKA Juuyoh / Flickr

In autumn, it often turns bright red and orange-red , and is one of the most important autumn-colored foliage trees in southern green areas. Du Mu's poem "Stop the car and sit to enjoy the maple forest in the evening, the frost leaves are redder than the flowers in February" is probably describing Liquidambar formosana.

TANAKA Juuyoh / Flickr

Soapberry

The leaves of soapberry are mostly even-pinnate compound leaves, that is, there is no leaf at the top of the rachis, and the total number of leaves is even. As one of the main roadside trees in the south, soapberry often has little presence in other seasons, but once autumn comes, the golden leaves of the tree are quite spectacular under the blue sky .

Banna Flower Wheel

In addition, its fruit is shaped like the longan of the same family, and people often ask "what good can it do?" Unfortunately, its aril is not edible, but it is rich in saponins, a natural surfactant that can be used instead of soap for washing clothes .

Don’t just eat longan when you see it｜David Eickhoff / Flickr

Bubbly | Alex Popovkin / Wikipedia

Golden pine

The golden pine is probably the most beautiful gymnosperm besides the ginkgo. It has an upright trunk and linear, flat and soft leaves that grow in clusters on short branches and radiate into discs, shaped like copper coins . In late autumn, the leaves turn golden yellow, which is very ornamental.

Golden pine in autumn｜plants.frisellanursery.com

In gardens, golden pine is known as one of the world's five major garden ornamental tree species along with Araucaria, cedar, golden pine and North American redwood.

Steven Severinghaus

Sycamore

The trunk of the phoenix tree is straight and the bark is often green, so it is also called the green phoenix. It has a beautiful shape, a large crown and a thick shade. It is said that "the phoenix is ​​a good tree and the phoenix lives there". It is a tree that the ancients cherished very much, so it has been widely planted in gardens of all dynasties. It is said that the famous saying "one leaf falls and we know that autumn has come" is related to the phoenix tree, which shows that the falling leaves of the phoenix tree should not be wasted.

Image: Banna Hualunjun

Baldcypress

Unlike the evergreen pines and cypresses we imagine, the bald cypress, which has adapted to warm climates, is a deciduous gymnosperm . Its feather-like compound leaves turn a beautiful orange in autumn and then fall off, which is indeed in line with the meaning of "falling feathers".

Conifers can also be as dazzling as flames in autumn｜HoroshilovAleksandr / wikimedia

For this reason, bald cypress is called " bald cypress " in English. Taxonomically, bald cypress is indeed a species of the Cupressaceae family. Among the gymnosperms, which are "not very populous", the Cupressaceae family is a geographically widespread group that includes not only various cypresses, but also various species that were originally considered to be in the Cupressaceae family, including the world's tallest tree (North American redwood) and the largest tree (giant sequoia).

Leaves and cones of Baldcypress｜Sciadopitys / wikimedia

Metasequoia

Friends living in the Yangtze River Basin have all seen Metasequoia. It is a beautiful deciduous conifer. Its leaflets are like feathers, not as hard as those of pine and cypress. In autumn, the whole tree turns into a brilliant golden color . If you are a student majoring in biology, the difference between Metasequoia and Baldcypress is almost a must-answer question when studying tree classification.

The leaflets of Metasequoia are broad, soft and opposite (left), while those of Baldcypress are alternate and thinner (right)｜Zhong Shushu (left); Agnieszka Kwiecień, Nova (right)

Metasequoia is called a "living fossil". Behind this term is the botanical history of Metasequoia being discovered in war and the turmoil of the world for tens of millions of years. Today, Metasequoia is planted in many places around the world, which is beautiful and spectacular.

Soseipapa/wikimedia

Nandina domestica

Nandina domestica is not a bamboo, but a small shrub of the genus Nandina in the Berberidaceae family, native to East Asia. Nandina domestica's pinnate compound leaves resemble bamboo leaves, and its slender branches can easily be mistaken for bamboo.

In China, Nandina domestica has become a common ornamental plant. Its green leaves will turn into a striking red in late autumn or winter when the temperature is low . In Japan, Nandina domestica is also considered a red-leaf plant. The entire Nandina domestica plant is poisonous , so it can only be viewed from a distance and not touched.

Nandina domestica｜Jack Holloway / flickr

Why do some trees shed their leaves while others don't?

After seeing the yellow leaves in the south, you may ask, why do some trees shed their leaves while others remain evergreen all year round?

Leaves are one of the nutritional organs of plants. Their main function is to carry out photosynthesis to provide energy for plant growth. Leaves are like a delicate instrument that requires the cooperation of both internal and external forces to operate normally.

With the arrival of autumn, the length of daylight, light intensity, temperature and rainfall all begin to decline, the photosynthetic efficiency of leaves begins to weaken, and the overall energy supply to the plant decreases; on the other hand, maintaining leaf growth also requires energy consumption. Therefore, whether the supply and consumption of energy can be balanced is an important factor in whether a plant decides to shed its leaves .

Deciduous forest｜Pixabay

In temperate regions with severe winters, most trees are deciduous, except for evergreen conifers that can tolerate sub-zero temperatures for a long time. In warm temperate and subtropical regions with relatively mild winters, most trees are evergreen .

Evergreen coniferous forest｜Pixabay

In areas with distinct alternations between rainy and dry seasons, rainfall levels may also affect whether plants choose to shed their leaves. For example, some desert plants will quickly sprout leaves, bloom and bear fruit when the rainy season arrives, but will shed their leaves and go dormant during the dry season.

Why do some plant leaves turn yellow?

Generally speaking, the leaves of normal higher plants (except algae) are green, which is the effect of chlorophyll. But in fact, in addition to chlorophyll, there are also pigments such as carotene and xanthophyll in the leaves. However, the content of these pigments in the leaves is usually low, and their colors are covered by chlorophyll and not shown. When chlorophyll is affected by low temperature and degraded, the yellow-based carotenoids will appear, making the leaves appear bright yellow .

Some turned red?

The reddening of leaves is a bit more complicated. In addition to being related to the decomposition of chlorophyll, it is also related to a newly generated pigment, anthocyanin . Generally speaking, anthocyanins are mostly found on the surface of petals and peels, but sometimes they also appear in leaves. In autumn, when the temperature is low and the temperature difference between day and night is large, the soluble sugar content in leaf cells will increase, which will promote the synthesis of a large amount of anthocyanins, making the leaves appear bright red .

Falling leaves have a rich variety of colors｜Chris Glass / Wikipedia

As for why leaves that are about to fall still contain anthocyanins, the current reasonable explanation is that anthocyanins, as an antioxidant reducing agent, can play a protective role and prevent light from damaging leaves in the transition period. This can also explain why the young leaves and tender shoots of many plants are red.

For example, the young leaves of Chinese toon in scrambled eggs are red｜TuChong Creative

After reading this, what are our friends in the South waiting for? Seize this autumn now!

Author: Banna Hualunjun, Uncle Zhong, Lupin, Attack of the Succulents

Editor: Little Towel, Mai Mai

Title image source: Pixabay