Vinegar or vinegar? Interesting Oxalis (three) stalks (leaf)

Produced by: Science Popularization China

Author: Qin Yalong (Institute of Botany, Chinese Academy of Sciences, Jiangsu Province, Nanjing Zhongshan Botanical Garden)

Producer: China Science Expo

sorrel

(Photo credit: Photo taken by the author)

All things in nature are full of infinite charm, and small flowers and grasses also have their own survival wisdom and scientific connotations. There is such a small grass, it is very common, its name is Oxalis corniculata L., some areas mistakenly call it [zhà] Jiangcao, it should be read as [cù] Jiangcao. Of course, it also has a familiar name - clover.

Next, let’s get to know Oxalis.

Oxalis joint

(Photo credit: Photo taken by the author)

There are many things to pay attention to when using the word "酢"...

"Oxalis" is a polyphonetic character. When pronounced as "cù", it is the same as "vinegar". It is paired with words such as "wine", "vinegar vessel", "vinegar flavor", "wine pulp", etc. The word "cù" is pronounced as "Oxalis". The genus name of Oxalis comes from the Greek root "oxys", which means sour, so Oxalis is also called sour grass.

There is another pronunciation of "zuò", which originally means the host and the guest toast each other, and is extended to mean socializing among friends. The common word combination is "chouzu", which means the host and the guest toast each other. The host toasts the guest, which is called "chou", and the guest returns the toast, which is called "zu". "Huainanzi·Zhushuxun" records that "the etiquette of "chouzu" is to show kindness." It records that the ancients conveyed friendship and joy through social etiquette.

What are the types of Oxalis in my country?

Oxalis is an annual or perennial herbaceous plant of the Oxalidaceae family. It is also known as sour clover, sour vinegar sauce, sour grass, etc. According to the Flora of China, there are five species of Oxalis in my country, namely Oxalis, white Oxalis, yellow Oxalis, large Oxalis and red Oxalis.

Oxalis species are distributed in most parts of China and can often be seen in the wild. In Northeast my country, North China, Northwest China and Southwest China, you can also see Oxalis alba with white flowers, but it is hard to find in the south of the Yangtze River.

Among the species recorded in the Flora, Oxalis grandiflora and Oxalis lutea are native to South Africa and are introduced and cultivated in my country mainly for potted ornamental flowers. Oxalis rubra, Oxalis chinensis and Oxalis triangularis, which are widely used for ground cover greening, have the same flower color, and are all foreign species introduced to my country from South America.

Oxalis joint, Oxalis white, Oxalis red, Oxalis

(Photo credit: Photo taken by the author)

Beautiful and magical leaves

The leaves of Oxalis plants are very unique, usually with three perfectly symmetrical leaflets, each with its own unique shape, color or pattern. Of course, there are some more peculiar varieties, such as the palm Oxalis with leaves like palm leaves and the lava Oxalis with leaves like volcanic lava, which are highly sought after by Oxalis lovers.

What's more interesting is that the leaves of Oxalis can sense sunrise and sunset, and can even cope with cloudy and rainy days. On sunny mornings, the leaves and flowers of Oxalis open their hazy eyes, stretch themselves, slowly spread out and smile at the sun; when it gets darker, the leaves and flowers of Oxalis are like children who are extremely afraid of the cold, each huddled up in a ball, shivering for fear of the cold wind; when cloudy and rainy days come, the leaves of Oxalis are like closed parasols, closing up early and going home.

This should be the wisdom of Oxalis leaves, growing towards the sun and feeling the sunshine and warmth.

Lava Sorrel

(Photo credit: Photo taken by the author)

Oxalis triangular-leaved, gradually folding its leaves in the evening

(Photo credit: Photo taken by the author)

Oxalis palmatum with palm leaves

(Photo credit: Photo taken by the author)

Mysterious underground rhizomes

The underground parts of Oxalis plants also vary in shape. They have fleshy bulbous or tuberous rhizomes with true roots growing on them.

Take Oxalis serrata as an example. The underground of Oxalis serrata is mainly divided into three parts: fibrous roots, fleshy roots and fleshy bulbs. It is like the garlic we eat, but the difference is that garlic does not have fleshy roots like white radish under Oxalis serrata. There are multiple bulbils distributed above the root system. They are large and small. Each bulbil is a complete bulb after being broken open. Each one is like a bunch of garlic, with cloves clustered together like garlic.

If you look closely at each of its bulbils, you will see that they are stacked one on top of another, resembling the bulbs of lilies. Unlike lilies, the bulbs of Oxalis serrata are inedible, but the white fleshy roots underneath are edible. Like the stems and leaves, they are also mainly sour, which is not something everyone can adapt to. People call them water radishes. From the pictures, we can also see that there are many bulbs of Oxalis serrata, and even if a small one falls off, it will reproduce rapidly. It has now escaped into the mountains and fields.

Different forms of the underground parts of Oxalis serrata

(Photo credit: Photo taken by the author)

Oxalis serrata underground bulbs

(Photo credit: Photo taken by the author)

Oxalis, the most commonly used plant in landscaping, is easy to identify. The pink umbel blooms at the top of the plant, and the five petals are arranged with rose-red stripes towards the base, attracting butterflies, bees or moths to visit and follow the stripes to explore the delicious nectar source.

The leaves of Oxalis are also very special. The light green leaves are like hearts, forming a perfect symmetry. The countless leaves on the plant form the shape of hills.

The underground tubers of Oxalis articulatus are even more magical. I believe that after seeing the picture, you will have a deeper understanding of its name. When we dig up tubers that have grown for a long enough time, we will find that except for the bottom group, the small tubers separated from it will be stacked up in a stacked manner. The longer the years, the more layers there are. Some advanced bonsai players will also expose the tubers that have grown for many years on the soil surface and use the stacked tubers as scenery to make miniature bonsai. Every year, the plant will bloom small pink flowers, which is extremely unique.

The hill-like plant of Oxalis joint

(Photo credit: Photo taken by the author)

Pagoda-shaped underground tubers of Oxalis

(Photo credit: Photo taken by the author)

The wisdom of flowers

The flowers of Oxalis plants come in a variety of colors, including yellow, red, pink or white, with five petals and sepals arranged in a shingle-like pattern like roof tiles.

A single flower of the genus Oxalis has two whorls of 10 stamens, 5 long stamens and 5 short stamens, and 5 styles. The arrangement of the two whorls of stamens and stigmas varies from species to species. In some species, the stigma is located above the two whorls of stamens, in some species, between the two whorls of stamens, and in some species, below the two whorls of stamens. This is called three types of styles in botany, namely long style, medium style and short style.

Take Oxalis articularis as an example, its five styles are located under two whorls of stamens, belonging to the short style type. From an evolutionary perspective, the style type of Oxalis is the result of its continuous evolution.

Why do I say this? This is because when the same kind of pollinating insects enter the center of the Oxalis joint to collect nectar, the pollen on the stamens will stick to the insects. Because the stigma of the Oxalis joint is hidden at the bottom, when the insect visits other flowers of the Oxalis joint, it will not bring the pollen stuck to its body to its stigma, thus perfectly avoiding inbreeding.

By the same token, when insects carrying short-style pollen visit flowers of other styles in the genus Oxalis, pollination will be completed and hybridization will occur, which is more conducive to the evolution and reproduction of Oxalis. This is the wisdom of Oxalis flowers.

Oxalis short-style flowers

(Photo credit: Photo taken by the author)

It is worth noting that although the red-flowered Oxalis and jointed Oxalis introduced to my country from South America are extremely brilliant when they bloom, they are not seen in real life after flowering, probably due to the lack of pollinating insects.

How are Oxalis seeds spread?

The flowering and fruiting period of Oxalis can last from February to September. Some flowers are still blooming, and some have already borne fruit. The fruit of Oxalis is a capsule with five edges, which is long and cylindrical.

When its fruit is ripe, the back of the capsule splits from the middle, revealing white "seeds". These white round grains are not its real seeds, but the aril wrapped around the seeds. The aril is exposed to the air, and the internal moisture gradually dissipates and then cracks, revealing the tiny reddish-brown seeds inside.

Afterwards, the aril will curl up to both sides to form a launcher. Once the fruit is shaken by external force, the launcher will eject the seeds, realizing seed sowing. The exquisite structure is amazing.

Oxalis oxyphylla

(Photo credit: Photo taken by the author)

Seeds from Oxalis capsule

(Photo credit: Photo taken by the author)

Conclusion

It should be noted that although the above-ground parts of some Oxalis plants taste sour when chewed, and the young stems, tender leaves and fleshy roots of some species can be eaten as vegetables; some can be used as medicine, such as the flora records that the whole plant of Oxalis species is used as medicine, and cattle and sheep can be poisoned and die if they eat too much of it; there are also many species that are difficult to distinguish, and are quite similar to plants of the same genus or different groups.

Therefore, if you are not 100% sure, remember not to treat Oxalis as a vegetable or medicine. It is enough for us to quietly appreciate the beauty of such moving flowers and leaves.

Editor: Sun Chenyu