Glossary

Awn (awn) is the botanical term for the stiff, bristle-like extension that projects from the seed head of many grasses. What most people in the San Lorenzo Valley know as the “barbed bristles” of foxtail — the structures that catch on fur and clothing and penetrate living tissue — are awns.

In native grasses, awns serve as dispersal tools: they catch on passing animals, help seeds move across soil surfaces, and in some species twist with changes in moisture to drive seeds into the ground. Native grass awns are not directionally barbed — they attach and release, doing their dispersal work without penetrating tissue.

Among the invasive annual grasses that have colonized the San Lorenzo Valley, the awn of foxtail is an entirely different structure. Foxtail awns are directionally barbed — they move in only one direction: inward. Once lodged in fur, skin, or living tissue, they do not work their way out — they migrate forward and inward.

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