sour dock vs sour grass

sour dock and sour grass both are nouns.

Word	Noun	Adjective	Verb	Adverb
sour dock	Yes	No	No	No
sour grass	Yes	No	No	No

As nouns, sour grass is a hypernym of sour dock; that is, sour grass is a word with a broader meaning than sour dock:

sour dock: European sorrel with large slightly acidic sagittate leaves grown throughout north temperate zone for salad and spring greens
sour grass: any of certain coarse weedy plants with long taproots, sometimes used as table greens or in folk medicine

Other hypernyms of sour dock include dock, sorrel.

sour dock (noun)	sour grass (noun)
European sorrel with large slightly acidic sagittate leaves grown throughout north temperate zone for salad and spring greens	any of certain coarse weedy plants with long taproots, sometimes used as table greens or in folk medicine