The iron tree finally blooms, which is much more difficult than "the iron tree blooms"!

Recently, the news that a very small wild plant species bloomed in Kunming Botanical Garden has attracted attention from the industry. This plant, called Tianmu Ironwood, originally grew in Zhejiang and bloomed for the first time after 34 years of ex situ protection.

Tianmu Ironwood in bloom (Photo source: Kunming World Expo Park)

It is normal for plants to bloom and bear fruit. Why does the ironwood only bloom once every 34 years? Is its flowering period longer than that of the iron tree? What is the difference between it and the iron tree? To understand these questions, we have to start with the origin of the ironwood.

Catkins endangered species

Located in the northwest of Zhejiang, Xitianmu Mountain has a unique landform and beautiful environment. It is a national forest-type nature reserve with more than 2,000 plant species, known as a "natural botanical garden". There are four rare and scarce plants on the mountain, known as the "Four Wonders of Tianmu".

Among the "four wonders", there is a kind of towering and hard tree. People have only found five such rare trees. They are all hundreds of years old, and the oldest one is more than 300 years old. In 1927, Chen Huanyong, a well-known modern botanist, conducted in-depth research on this plant that was only found in Tianmu Mountain and named it "Tianmu Ironwood", which is still used today.

Scenery of West Tianmu Mountain (Photo source: Tianmu Mountain Scenic Area Website)

Tianmu Ironwood is also known as Zhejiang Ironwood and Rui's Ironwood. It belongs to the genus of Ironwood in the family Betulaceae. It has a majestic tree shape, with a diameter of more than meters and a height of more than 20 meters, showing an extraordinary and spectacular appearance. The cross section of the trunk presents a light color, but the texture is clearly discernible. The bark is dark gray and feels rough, showing the unique natural charm of Tianmu Ironwood.

The male and female flowers of the ironwood have different shapes and colors. The female flowers are lush green with membranous bracts, while the male flowers are light yellow, with typical catkins. Catkins are one of the indefinite inflorescences, which are densely packed unisexual flowers in spikes, similar to foxtail grass, with the flower axis usually drooping. The most representative ones are the Betulaceae and Salicaceae plants.

The catkins of the ironwood tree sway in the wind (Photo by Ye Xiyang)

The distribution range of Tianmu Ironwood is extremely narrow , mainly limited to the northwest of Zhejiang Province, and the number is very small, with only five plants left in the wild. Moreover, due to its long flowering period, it often takes more than 20 years to see its flowers in full bloom. These characteristics make it a veritable endangered species. Therefore, it has received much attention and protection from the country, and has been listed in the list of national first-class key protected wild plants, and has been included in important protection plans such as the "National Extremely Small Population Wild Plant Rescue and Protection Project Plan" (2011-2015).

There are two main ways to protect Tianmu Ironwood: one is to protect it at its place of origin , which is to establish a special protection area in West Tianmu Mountain to allow it to reproduce and grow naturally; the other is to carry out ex situ protection , which is to transplant it to botanical gardens across the country. The Tianmu Ironwood mentioned in the Kunming Botanical Garden, which took 34 years to bloom, is the best proof of this.

As strong as steel and versatile

The genus Ironwood to which Tianmu Ironwood belongs has a small number of species and numbers. There are 7 species of Ironwood in the world, and 3 of them are found in my country, namely Yunnan Ironwood, Tianmu Ironwood and Multi-veined Ironwood. Tianmu Ironwood is the only Ironwood plant in southeastern my country.

The ironwood tree has a majestic body, which can be more than 20 meters tall. It takes two or three adults to hug its thick trunk. It shows a mighty and tall momentum, giving people a sense of security. This is one of the reasons why ironwood is loved by the working people in ancient China. "In the southeast of the sea there is Shixi Mountain, on which there is a tree called ironwood. Five hundred years old is spring, and five hundred years old is autumn. It lives for a thousand years, and its circumference is no more than one foot. Its quality is like iron..." , the Han Dynasty "Shenyijing" recorded.

Ironwood (Photo source: Flora of China)

If we were to choose the hardest trees in the world, ironwood would definitely be in the top three.

The genus name of ironwood, "Ostrya" (Latin), means a tree with hard wood. Ironwood, which is harder than steel, can be used as raw material for furniture, ships, special buildings, and aerospace parts, and has a wide range of uses. According to historical records, the ships that Zheng He took on his seven voyages to the West were made of ironwood. These ships were not only harder than steel, but also resistant to water and fire.

Furthermore, the growth rate of ironwood is very slow, often taking hundreds of years to mature, and even decades to bloom and bear fruit. Because of this, ironwood plays an indispensable role in maintaining the local ecological balance .

For scientists, ironwood is a vivid natural history. Through in-depth research, we can gain insight into the growth and reproduction secrets of local species. This is the scientific value of ironwood.

The flowering of cycads varies from place to place

Some people may ask, the iron tree takes decades to bloom, so it is completely not on the same level as the iron tree in the saying "the iron tree blooms and the dumb speaks"?

Yes, the two are not in the same league, but the one that is better is the iron tree.

Cycad (Photo source: Flora of China)

Cycads and ironwood are two completely different plants . Cycads are scientifically known as Cycads, and belong to the Cycadaceae family of the Cycadales order. They are named because of their great demand for iron during their growth. Cycads, as the most primitive type of angiosperms, have a long history of 280 million years. In the Jurassic period, cycads were distributed all over the world and were the main food source for dinosaurs, witnessing an important stage in the evolution of life on Earth.

The cycad tree grows very slowly, and its lifespan can reach 2,000 years. Its most notable feature is that it blooms seldom and irregularly. The flower of the cycad tree, known as the Phoenix Tail Banana, not only has a high ornamental value, but also has considerable medicinal value.

Flowers of the iron tree (Source: Flora of China)

How often does the cycad tree bloom? The answer is actually closely related to its growing environment. As a tropical plant, the cycad tree prefers a warm and humid climate, so temperature is a key factor affecting its flowering .

In tropical regions, the cycads bloom almost every year; in subtropical regions, their flowering period may become sparse, blooming only once every few years; in temperate regions, it is even rarer, perhaps blooming only once every few decades. However, with the improvement of people's maintenance technology, when the growth conditions are suitable, the cycads in the south can bloom happily between June and August every year, and their flowering period can last for a month.

From this, some people speculate that the originator of the proverb "When the iron tree blooms, the dumb speak" is most likely a northerner, because they have a deeper understanding of the rarity of the iron tree blooms.

From a scientific point of view, it takes decades for ironwood, especially Tianmu ironwood, to bloom, which is different from the ironwood that blooms every year. The deeper reason why the Tianmu ironwood in Kunming Botanical Garden, which blooms only every 34 years, has attracted the world's attention is that its blooming is not only an ode to the tenacity of life, but also a display of the magical charm of nature. Let us cheer for this miracle of life together, and look forward to Tianmu ironwood continuing to show us more mysteries of nature.

References:

1. Paper "Community Structure and Species Diversity of Rare and Endangered Plant Ironwood", author Luo Yuan et al., Zhejiang Agricultural Sciences, 2018, No. 11

2. Paper "Genetic Diversity Analysis of the Endangered Plant Ironwood", author Wang Zuliang, Ding Lixia, etc., Journal of Zhejiang Forestry College, No. 1, 2008

3. Paper "Flower and pollen morphology of Tianmu ironwood", author Zhang Ruohui and Zhang Jintan, Journal of Zhejiang Forestry College, No. 1, 1988

Author: Wei Deyong

Member of Guangdong Shenzhen Writers Association

Editor: Dong Xiaoxian