Pineapple weed (Matricaria discoidea, Asteraceae) is unique for a couple of reasons. First, the flower heads lack the prominent ray florets typical of the aster family, possessing only cone-shaped aggregations of small disc florets. Second, the finely-divided leaves produce a distinct pineapple-like scent when they’re crushed (Brandenburg 2010).
Despite these interesting traits, pineapple weed (also called disc mayweed) is often overlooked because it’s so common. Native to the northwestern United States, it has spread over much of the continent (Brandenburg 2010). It can usually be found in abundance in open, disturbed areas like trails, roadways, and fields. These particular photos were taken along the edge of a farm field.
Brandenburg, D.M. 2010. National Wildlife Federation Field Guide to Wildflowers of North America. Andrew Stewart Publishing, Inc., New York, NY.