灰罗勒（学名：Ocimum americanum），为一种带有绒毛的一年生草本植物。花为白色或淡紫色。这种植物有很好的药用价值。

Ocimum americanum, known as limehairy or "hoary basil", is an annual herb with white or lavender flowers. It is used for medicinal purposes. Despite the misleading name, it is native to Africa, the Indian Subcontinent, China, Southeast Asia. The species is naturalized in Queensland, Christmas Island, and parts of tropical America.