Aaron's beard may refer to the following plants having numerous stamens or threadlike runners:
- Cymbalaria muralis (Ivy-leaved toadflax, Kenilworth ivy), native to south and southwest Europe.
- Hypericum calycinum (Great St. John's-wort, Jerusalem star), widely cultivated.
- Opuntia leucotricha (Arborescent prickly pear, Aaron's beard cactus), a species of prickly pear cactus, endemic to Mexico.
- Saxifraga stolonifera (Creeping saxifrage, strawberry geranium), native to Asia.
- Spiraea salicifolia (Bridewort, willow-leaved meadowsweet), native to Eurasia, cultivated
- Verbascum thapsus (Great mullein, greater mullein, common mullein, Aaron's rod), native to Europe, northern Africa, and Asia.
The name derives from a Biblical quotation referring to the patriarch Aaron:
<blockquote>"Behold, how good and how pleasant it is for brethren to dwell together in unity!<br/>
It is like the precious ointment upon the head, that ran down upon the beard, even Aaron's beard: that went down to the skirts of his garments"<br/>-- Psalm 133:1-2 (King James Version)</blockquote>
<gallery mode="packed" widths="140" heights="140">
File:Cymbalaria muralis close up.jpg|Cymbalaria muralis
File:Hypericum calycinum Tasmania.jpg|Hypericum calycinum
File:Opuntia leucotricha Bl.jpg|Opuntia leucotricha
File:Saxifraga stolonifera Harvest Moon 2.jpg|Saxifraga stolonifera
File:Spiraea salicifolia - Rosaceae - National Botanic Garden of Belgium 01.jpg|Spiraea salicifolia
File:Starr 040723-0030 Verbascum thapsus.jpg|Verbascum thapsus
</gallery>