墙上芦苇

墙上芦苇

Literally means:

reed standing on top of a wall that is not well-grounded

Actually means:

It is from the proverb: 墙上芦苇，头重脚轻根底浅 (a reed on top of the wa has a heavy head, a weak stem and a petty root). Reeds live in wetlands or shallow water areas, and their roots are generally deeply down inside the earth.

If a reed is planted on top of a wall, its root is not going to develop well owing to lack of soil, and the reed becomes "petty-rooted". A tall reed with such a small root is imbalanced and unsteady.

This phrase figuratively means that one does not have a solid foundation and is poor in ability. It can also refer to certain arties or writing styles that are empty in content and impractical. Derogatory.

来自“墙上芦苇，头重脚轻根底浅。”芦苇原本生长在湿地或浅水区，有比较发达的根。如果把芦苇栽在墙头上，由于缺乏生根的土壤，就会“根底浅”，而根底浅又会使长高了的芦苇出现头重脚轻的不平衡现象。

墙上芦苇，比喻基础不扎实，没有实在的本事。也指空泛地大发议论，而没有内容或解决不了问题的文章或写作作风。具有贬义色彩。