"The water chestnut leaves linger in the lotus wind, and the lotus deep boat passes. Feng Lang bowed his head and smiled, and Biyu scratched his head and fell into the water. This is a wonderful picture of the water town in the south of the Yangtze River painted by the Tang Dynasty poet Bai Juyi. In the depths of the lotus pond, the water chestnut leaves are swaying, adding to the joy of the beautiful woman's boating.
In Huai'an, Jiangsu Province in summer, the villagers' boats plucking lings make a path among the green leaves
When it comes to water chestnut, friends in the south must not be unfamiliar, and the sweet and soft water chestnut is an unforgettable hometown memory for many people. So, in addition to being a delicacy, how much do you know about this plant?
Northerners said they had eaten it too
Source: Xiaohongshu @吭哧吭哧 foraging little pigs
In the leaves of the fields, the water chestnut is reflected in the pool
Water chestnut is a general term for the genus Trapa in the family Celandaceae, a class of floating aquatic herbaceous plants found in tropical, subtropical and temperate regions of Eurasia and Africa. It is usually rooted in the silt at the bottom of the water and has a long, soft, vine-like stem that connects the part of the plant that floats on the water's surface. There are green feathery structures at the underwater stem nodes, which are often mistaken for submerged leaves.
Have you ever seen the water chestnut pulled out?
Source: en.vcci.com.vn
In fact, this structure has adventitious roots with assimilation function, which can replace leaves to exercise part of the photosynthesis function. The true submerged leaves are only seen on small seedlings and fall off soon after. Corresponding to the name of the plant, its floating leaves are diamond-shaped or almost rhomboid, rosette-shaped, and the petiole has bulging air sacs that help it float on the water.
Structure of the Trapa natans plant
Source: References [2]
The flowers of the water chestnut are small and white. The water chestnut used for food is the horned fruit that bears after flowering. The "horn" of water chestnut comes from the enlarged calyx. The flowers of the water chestnut have a total of 4 sepals, of which there can be different numbers that expand during development, so the water chestnut has a maximum of 4 horns. The flowers of the water chestnut bloom above the surface of the water, and after bearing fruit, they turn underwater, and the fruit ripens underwater.
Ouling's small white flowers
Photo: Wei Zhourui
Although the rhombic leaves that float on the surface of the water are very distinctive, this is not exclusive to rhododochri, and some aquatic plants have a similar shape. For example, the willow plant native to tropical South America also has regular diamond-shaped floating leaves, which are cultivated as ornamental plants in some places. Its flowers are yellow, large and showy, and the petiole does not have bulging air sacs, which is different from that of water chestnut.
菱叶丁香蓼(Ludwigia sedioides)小叶子排得也很令强迫症舒适
Source: inaturalist.org
The form is honest and beautiful, and the branches are inseparable
Rhomboids have complex and diverse morphological variations, especially fruit morphology. For a long time, there have been different opinions on the classification of species of Rhomboids, and the largest number of delineation methods has even reached as many as 70.
First put a big picture for friends who have never seen water chestnut, you can directly steam it in the shell and eat it, or you can peel it out raw and make "water chestnut rice" as an ingredient. Source below: Documentary "Flavor of the World"
The Flora of China identified 15 species and 11 varieties of domestic water chestnut and placed them in a separate family according to their unique morphology, and later molecular taxonomy merged the water chestnut family with the celandaceae family. There are two diversity centers, one in the Heilongjiang River basin and the other in the middle and lower reaches of the Yangtze River. In the latest taxonomic process, the Chinese water chestnut was finally merged into two species, namely the fine fruit of the wild water and the Ou ling.
Fruit morphology of the Ouling complex
Source: References [2]
The fine fruit field water chestnut is also known as the four-cornered carved leaf water, compared with the Ou Ling leaf is smaller, more "angular", the base is wedge-shaped, and the upper edge has a missing carved sharp serration. Its fruit is also smaller, with 4 elongated, sharp horns. Other domestically produced Rhodophiles have been incorporated into the genus Eurin, so this species has a fairly rich morphological diversity. Cultivated water chestnut is also bred by Ouling.
细果野菱Incisa Trappe的植株和果实
Source: inaturalist.org
In the past, the grass in the pond turned into a table dish
Wild water chestnut is generally a thin fruit, how does it become fat and plump on the table?
Sweet and soft glutinous water chestnut dumplings
Source: Documentary "Flavor World"
In fact, human domestication of water chestnut has a very long history. A large number of complete water chestnuts have been unearthed at the Tianluoshan site in Yuyao, Zhejiang, covering all stages from wild state to domesticated state. These water chestnuts can be traced back to the Neolithic Hemudu culture 6,300-7,000 years ago. The site has also unearthed many fragments of water chestnut for human consumption, proving that the ancestors have domesticated water chestnut for food at least that time.
Water chestnut unearthed at the Tianluo Mountain site
Source: References [6]
A recent study based on whole-genome sequencing sheds deeper light on the domestication process of water chestnut. About 1 million years ago, the ancestors of the water chestnut were divided into two species, the European water and the fine fruit wild water chestnut. Wild Ouling is divided into diploid and tetraploid, of which diploid is the primitive type. About 20-300,000 years ago, climate turmoil led to the hybridization of wild diploid Orin with Wild Fruit Wild Ling, resulting in tetraploid Orin. Cultivated water chestnut originated from the diploid Ouling in the Yangtze River basin, and its domestication occurred in the Neolithic period, consistent with archaeological and documentary evidence. In the Southern Song Dynasty, the cultivation of water chestnut was further improved, producing special varieties such as Wuling.
Morphology of water chestnut with different ploidies and species
Source: References [4]
Stepping on the spring river song together, singing Cailing songs
With a long history of use in China, water chestnut is also widely used in classical culture. "Erya", "Shuowen Jiezi" and other documents have been recorded on the ling, and the ancient titles of the ling, such as 蓤, 芰 (jì), water chestnut and so on. In the pre-Qin period, water chestnuts were used in sacrifices, such as the "Zhou Rites" has a record of "the reality of jiazhen (biān), water chestnut, chestnut, and preserve". The beautiful shape of the rhomba is also used in architectural art as a decoration for caissons.
"The well, the image of the east well, the water chestnut, the things in the water; "Painting water chestnuts is also for good luck.
In literary creation, the elegant image of the water rhombus bathing in the clear waves also gives it a noble meaning. In Qu Yuan's "Lisao", the "芰" in "making lotus for clothes, and collecting hibiscus for clothes" refers to Ling.
In the process of long-term cultivation of water chestnut by the people, a unique water chestnut picking culture was also born. As early as the Spring and Autumn Period and the Warring States Period, the ballad of "Cai Ling" was popular in Chu. "Huainanzi" cloud "Those who want beauty and harmony must first start with "Yang'a" and "Cailing", indicating that "Cailing" is probably a more popular song born from the genus of labor trumpets. With the development of the times, Cailing songs have gradually been endowed with richer connotations. Song people Luo Yuan pointed out, "Wu Chu's customs, when the Ling is ripe, the scholars and girls are in harmony with Caizhi, so there is the song of Cai Ling to harmonize", young men and women to Cai Ling Song to harmonize, so that Cai Ling has become a cultural symbol to express love.
Now the people of Jiangnan will also pick Ling at night, in order to sell fresh in the market the next morning, Cai Ling culture is still the inheritance of hard work.
In Nanliang Xu Mian's "Cai Ling Song", "Cai Cai can't return, look at Fang Yanling." If you meet a bereaved person, you will promise each other in advance", which vividly and meticulously depicts the love heart of the Cailing girl. Cailing culture prevails in the south of the Yangtze River. Xie Lingyun of the Southern Song Dynasty has a poem "Cai Ling tunes are easy to be anxious, and Jiangnan songs are not slow." Tang Luobin Wang also wrote, "There are many festivals in the south of the Yangtze River, and the wine has passed through many times. Stepping on the spring river song together, singing Cailing songs". These poems contain strong local feelings, and Cailing has gradually become a cultural symbol representing the south of the Yangtze River.
The literati also loved to eat a bite of "moonlight on the lotus pond", comparing themselves with the whiteness of water chestnut rice
Source: Documentary "Flavor World"
Although the multi-talent is beautiful, it is also worrying to broadcast far
In addition to serving as a delicacy for food, water chestnuts can also play a role in other fields. The peel of water chestnut is a traditional herb that contains a variety of bioactive components. In addition, it has excellent performance in absorbing pollutants such as heavy metals, and can be used to purify water bodies.
However, this treasure trove of plants is not flawless, and outside of its place of origin, it can cause serious ecological disasters. It was introduced to North America as an ornamental plant before 1859 and became an invasive plant after its escape. Due to its rapid growth, the water chestnut will quickly cover the water surface and block the sunlight, causing a large number of submerged plants to die, changing the structure of the aquatic community and the dissolved oxygen concentration of the water body, and indirectly threatening the survival of aquatic animals. It is estimated that in the United States, the damage and control costs caused by the rhombic can reach $200 million per year. How to prevent and control the flooding of water chestnut is becoming a serious issue for ecological protection in the Americas.
Water chestnut leaves that cover the surface of the water
Photo: Wei Zhourui
There are many other floating leaf invasive plants like water chestnut, the most famous of which is water hyacinth (water hyacinth). It is native to South America, belongs to the Yujiu flower family, and the petiole is swollen into a spherical shape, so it is called water hyacinth. Its flowers are large and beautiful, and they are of great ornamental value. However, it is also very reproductive. After being used as an ornamental plant or fodder to the world, due to the loss of the control of the natural enemy water hyacinth weevil, the water hyacinth quickly encroached on water bodies in various places, becoming an ecological disaster that plagued the world. On the mainland, the waters south of the Yellow River Basin are all poisoned, and how to effectively prevent and control and use water hyacinth is being studied.
密集生长的水葫芦Eichhornia crassipes
Photo: Wei Zhourui
Piāo, also from South America, is also a serious invasive floating aquatic weed. Because of its form, it is also commonly known as "water cabbage", but it is not related to cabbage, belongs to the Araceae family, and is closer to taro. The asexual reproduction of the plant is very strong, and the plant grows many creeping branches, which break to produce new individuals. In the case of poor prevention and control, it will quickly cover the water surface and endanger the ecosystem.
铺满河面的“水白菜”（大薸Pistia stratiotes）
Photo: Wei Zhourui
"Sending Tingzhou Lanyi to the evening, Lingge was in tears. "Water chestnut is not only a delicacy on the table, but also a local memory of the water town in the south of the Yangtze River, not only a precious gift from nature, but also the crystallization of the wisdom and labor of the ancestors. When we taste this mouthful, what kind of situation will come to our minds?
bibliography
[1] Chen Jiarui. Flora of China, Vol. 53, No. 2 [M]. Beijing: Science Press, 2000.
[2] Ding Bingyang, Jin Xiaofeng.Taxonomic study of Rhombic plants in China[J].Guangxi Botany,2020,40(01):1-15.
[3] Xia Yan.Ecological and cultural interpretation of ancient Chinese "ling" cognition[J].Journal of Tianjin Normal University(Social Sciences),2010(03):43-47.
[4] Lu, R.-S., Chen, Y., Zhang, X.-Y., Feng, Y., Comes, H. P., Li, Z., Zheng, Z.-S., Yuan, Y., Wang, L.-Y., Huang, Z.-J., Guo, Y., Sun, G.-P., Olsen, K. M., Chen, J. and Qiu, Y.-X. (2022) Genome sequencing and transcriptome analyses provide insights into the origin and domestication of water caltrop (Trapa spp., Lythraceae). Plant Biotechnol. J., https://doi.org/10.1111/pbi.13758
[5] Fan, X., Wang, W., Wagutu, G.K. et al. Fifteen complete chloroplast genomes of Trapa species (Trapaceae): insight into genome structure, comparative analysis and phylogenetic relationships. BMC Plant Biol 22, 230 (2022). https://doi.org/10.1186/s12870-022-03608-7
[6] Guo, Y., Wu, R., Sun, G. et al. Neolithic cultivation of water chestnuts (Trapa L.) at Tianluoshan (7000-6300 cal BP), Zhejiang Province, China. Sci Rep 7, 16206 (2017). https://doi.org/10.1038/s41598-017-15881-w
[7] Kathryn Monacelli, Douglas A. Wilcox. Competition between two floating-leaved aquatic plants. Aquatic Botany, 172, 103390 (2021). https://doi.org/10.1016/j.aquabot.2021.103390.
Written by | Wei Zhourui
Part of the picture | Picture worm creativity
WeChat edit | Zhao Zhiyu