"All plants and trees are decaying" comes from Song Yu's Nine Arguments. Here refers to the ups and downs of vegetation, inheriting the "five or six years" of the previous sentence, suggesting that it has been in Shu for many years, and at the same time echoing the "old" of the next sentence, which is darker than itself. When the poet came to Chengdu, thanks to the help of relatives and friends, he lived a relatively stable life in the thatched cottage, but he never forgot his homesickness and love for his loved ones. Because of the "military blockade", he couldn't go back to his hometown and had to live on the edge of Jinjiang. The word "old" on the "old riverside" is sad and gloomy and inexhaustible.