lichen lividus

例句：

1. 1. The lichen on the rock wall is a beautiful shade of green.
   岩石墙上的地衣是美丽的绿色。
2. 2.Lichen are common in alpine regions due to their ability to survive in cold and dry conditions.
   由于它们能在寒冷干燥的条件下生存，地衣在高山地区很常见。
3. 3.Lichen are used as natural pigments in paints and dyes.
   地衣被用作油漆和染料中的天然色素。