The official website of the Elkhorn Slough Foundation and Elkhorn Slough National Estuarine Research Reserve
Elkhorn Slough Plants: Santa Cruz Tarplant

Scientific Name:
Holocarpha Macradenia

Family:
Asteraceae
(Sunflower family)

Found at the Slough:
Grasslands, Coastal Prairie

Did you know...
Reintroduction of grazing, or a carefully managed mowing regime have brought back populations that were previously thought extinct

Santa Cruz Tarplant (sometimes called Tarweed) is a California endangered, federally theatened species. This pretty little native is known from grasslands and prairies on coastal terraces below 400 feet in elevation. Historically, it occurred from Monterey County north to Marin County. The only known population in the Elkhorn Watershed is in a Coastal Prairie habitat found on an ESF-managed property (Porter Ranch).  The next closest known population is just over five miles to the north, at the Watsonville Airport.

The plant is mostly threatened with habitat loss or change and invasions of non-native plants.  The populations of many of the Coastal Prairie wildflowers were dependent upon large grazing animals (like Elk), which have disappeared from the area.

It typically grows on deep loam and sandy loam soils with a subsurface clay component, which hold moisture longer into the growing season compared to the surrounding sandy soils.  The plant has a deep taproot that allows it to survive and flower late into the summer, after most other wildflowers have gone dormant. The seeds may last many years in the soil.  Reintroduction of grazing, or a carefully managed mowing regime have brought back populations that were previously thought extinct.

More on Santa Cruz Tarplant in Elkhorn Slough:

Links / sources:

 

 

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