Assertion: pear's pear | /r/HasProperty | pyrus ussuriensis
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Source sentences:
text: Cold-hardy rootstocks of the Siberian pear (Pyrus ussuriensis) and the Snow pear (P. nivalis), are also used, though the Siberian pear rootstock is very susceptible to pear decline, and the Snow pear rootstock is susceptible to fire blight.