Aaron's beard

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Aar·on's beard

 (âr′ənz, ăr′-)
A shrubby semi-evergreen plant (Hypericum calycinum) of Eurasia, having yellow flowers with numerous protruding stamens and often grown as a ground cover. Also called rose of Sharon.

[From the prominent tufts of stamens, in reference to Psalms 133:2.]

Aaron's beard

(Plants) another name for rose of Sharon1
References in periodicals archive ?
Verses 2 and 3 repeat the Hebrew verb "to go down" in three places: running down Aaron's beard, running down Aaron's collar, and falling dew.
It is like precious oil upon the head, coming down upon the beard, even Aaron's beard ...
Aaron's beard (Hypericum calycinum), bright yellow; late spring.