pleurisy root vs silkweed

pleurisy root and silkweed both are nouns.

Word	Noun	Adjective	Verb	Adverb
pleurisy root	Yes	No	No	No
silkweed	Yes	No	No	No

As nouns, silkweed is a hypernym of pleurisy root; that is, silkweed is a word with a broader meaning than pleurisy root:

pleurisy root: erect perennial of eastern and southern United States having showy orange flowers
silkweed: any of numerous plants of the genus Asclepias having milky juice and pods that split open releasing seeds with downy tufts

Other hypernyms of pleurisy root include milkweed.

pleurisy root (noun)	silkweed (noun)
erect perennial of eastern and southern United States having showy orange flowers	any of numerous plants of the genus Asclepias having milky juice and pods that split open releasing seeds with downy tufts