A small St John's wort, Hypericum gentianoides, of eastern North America, having tiny yellow flowers and scale-like leaves; also called nit-weed, pine-weed.
Origin
Early 19th century.
Definition of orange grass in US English:
orange grass
noun
US
A small St John's wort, Hypericum gentianoides, of eastern North America, having tiny yellow flowers and scale-like leaves; also called nit-weed, pine-weed.