Knowledgebase

Unidentified Silphium Species #880708

Asked August 08, 2024, 1:26 PM EDT

Hello, I was out cataloging native plants and stumbled upon what appeared to be a Silphium/cup plant species and have been unable to identify which one. All the ones I've found that are recorded to be in Maryland have different leaves. Could you help me out? Thanks in advance.

Harford County Maryland

Expert Response

There are some ID keys to genus Silphium available online that might be useful; we'll link a couple below. Plants in the aster family (to which Silphium belongs) sometimes rely on fine details of the flower structure (like the phyllaries) to separate similar-looking species, but in the case of Silphium, foliage shape alone might be sufficient to narrow down the possibilities. Except for one species with much smaller leaves, Silphium is not native to Maryland according to most sources (there isn't complete agreement), so plants like the one pictured may have "escaped" from a garden and seeded into a natural area.
  • North Carolina Botanical Garden: Flora of the Southeastern United States -- Key to Silphium
  • Flora of North America -- Silphium
Our best guess is that the pictured specimen is Virginia Cup Plant, Silphium perfoliatum subspecies connatum, sometimes listed as just Silphium connatum. According to the Flora of the Southeastern United States, this subspecies can occur, albeit rarely, in Maryland.

Miri
Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied August 09, 2024, 12:05 PM EDT

Loading ...