Assertion: bitterness's root | /r/HasProperty | thick-walled stone cells
Facets:
Source sentences:
text: The genus Apocynum contains only four species, two of which Apocynum androsaemifolium and A. cannabinum, or Black Indian Hemp, resemble each other very closely, the roots being distinguished by the thick-walled stone cells, which in the former are found in an interrupted circle near the middle of the bark, and in the latter are absent.