The idiom "Never fully severed ties" is almost universally known, metaphorically describing a situation where people who have seemingly broken off ties still maintain deep emotional connections. This idiom originates from a well-known natural phenomenon: when a fresh lotus root is broken, although the main part of it is completely separated, there are still many fine threads connecting the two ends of the break. Why are these fine threads so elastic?
If we observe the fine threads under a microscope, we can uncover their secret. It turns out that each lotus thread we can see with our naked eye is not a cylindrical structure, but a flattened one composed of 3 to 8 even finer threads. Interestingly, each of these finer threads is coiled like a spring, exhibiting great elasticity. If our hands could become small enough, we could stretch the threads by pulling on their ends, and then release them to let them retract.
So, what is the structure of these resilient fine threads? Botanists tell us that they belong to a transport system called xylem, which is specifically used to transport water and inorganic salts dissolved in water. Sometimes, the inner walls of plant xylem show special thickenings in certain areas, taking on various textures such as annular trapezoids or net-like structures. However, the xylem walls of lotus roots are particularly unique. The thickened spiral sections on their inner walls form what botanists call spiral xylem. When a lotus root is broken, the spiral-thickened sections of the xylem walls detach, forming spiral-shaped fine threads just a few micrometers in diameter. Under external forces, these fine threads stretch into "miniature springs", remaining intact within certain elastic limits, with a maximum length of about 10 centimeters. In fact, not only lotus roots contain such fine threads. Other parts of the lotus plant, such as leaves, leaf stems, flower stems, petals, and lotus heads, also show fine thread connections after being broken, although some of these fine threads are too tiny to compare with those of lotus roots.
The phenomenon of "Never fully severed ties" inevitably reminds us of a valuable medicinal plant - Du Zhong. Many people have tried breaking the bark or even leaves of Du Zhong, only to find countless strong white threads, presenting a state of "skin broken, threads still connected" or "leaf broken, threads still connected". Although it shares similar manifestations with lotus roots, the underlying reasons are completely different. The fine threads of Du Zhong are not xylem tissues, but its latex. Due to the presence of many latex ducts in Du Zhong's bark, these ducts can secrete a white cellular fluid, which contains a large amount of rubber components and is therefore called Du Zhong gum. When the bark of Du Zhong is broken, rubber threads connect the two cut surfaces. We know that rubber threads are highly elastic, much like the rubber bands we often see in daily life. Therefore, even if the bark is torn off, the rubber threads inside still require force to break them.