Is the willow one or two?

The source of the word "Liu Yang" is the most famous book in ancient times: "I used to go to Yiyi, Liu Yang, and now I'm here, it's raining"; The most famous one in the contemporary era is Chairman Mao's Answer to Li Shuyi: "I lost my pride, Yang Jun lost my willow, and the willow was blown to the sky." It gives people the impression that willow is a kind of plant, that is, weeping willow, or weeping poplar, which is also the plant knowledge of the ancients. "Mao Zhuan" notes: "Zhe, also"; "The Warring States Policy and the Western Zhou Dynasty Policy" notes: "Chu has Yang, and those who go to the willow shoot it with a hundred paces, and it will hit the target with a hundred paces" (this is the origin of "going through the Yang with a hundred paces", which can also be written as "going through the willow with a hundred paces"); The Book of Songs: "There are mulberry trees in Osaka and poplar trees in Kyrgyzstan".

ⅵ, sound xí, refers to the place with low humidity, such as beach, river bank or sandy land, which is the favorite growth environment for willow trees. Willow likes light, is not tolerant of shade, and often grows in treeless areas, river banks or on both sides of sidewalks, which conforms to the spleen of willow. Li Yu has this understanding of willow's bad temper: "There is a lot of joy in planting trees, but there is also a section for those who are not elegant: the branches and leaves are dense, and there is no leakage of moonlight ... So at the beginning of planting, we should plan ahead and leave a little time for the full moon to appear, so that day and night can benefit from it."

The permeability of willow brings the poetry of "willow shoots on the moon, people meet after dusk" Because the ancients who lived by the water often had close contact with the willow, they would naturally refer to a certain situation of human society through the appearance of the willow, and turned the landscape language into the language of love, and the willow became a symbol of nostalgia in the traditional culture of China. For example, Liang Yuandi's poem: "Wushan martial arts chief, weeping willows return to weeping willows."

In the Ming Dynasty, Li Shizhen "offended" the poems deposited on willow trees in Compendium of Materia Medica. He divided the willow into two kinds of plants: "the branches are hard and upright and called yang;" Those with weak willows are called willows, which cover the first class and the second class. " How can "difficult rise" have the charm of "Yi Yi"? In Li Shizhen's view, willow is willow, and "Yang" means "Yang". "Yang" means flying and rising. Although the normal state of willow is "a tapestry of thousands of strands of green silk hangs down", won't the willow branches in the wind also rise? And catkins "only know the sky, make the snow fly", isn't it also "Yang"? Why can't Liu be called Yang?

In the plant kingdom, Populus and Salix belong to Salicaceae, but they are two different genera: Populus pollinates by wind and Salix pollinates by insects. However, they are similar in that the number of seeds is large and small, they like light but are not tolerant of shade, and their regeneration ability is very strong. Perhaps because there are too many similarities between the two, in order to call this "later discovered" tree species, the ancients drew the word "Yang" from the word to refer to the same brother of willow.

Salix lacks fossil evidence to show its evolutionary origin, but Salix and Populus have grown in this world since Cretaceous. It is my guess that the ancients found willows in willows: there may be more willows by the water, and willows are closer to the lives of the ancients and easier to be noticed; Yang is closely related to the life of the ancients and is more backward than Liu.