Holocarpha macradenia, commonly known as the Santa Cruz tarweed, is an endangered plant endemic to certain coastal terraces in Northern California. Its principal range is in Santa Cruz County and Monterey County, but smaller colonies have been found slightly to the north. Specifically Santa Cruz tarweed (Holocarpha macradenia) likes to inhabit terraced locations of valley or prairie grasslands with underlying sandy clay soils. Its characteristic habitat, the California coastal prairie ecosystem, may be the oldest stable ecosystem of the temperate world, dating about 600,000 years. The growth habit is on a single erect stem, with a few short branches starting halfway from the base. It has characteristic yellow daisy-like flowers, with black anthers giving the appearance of striking black dots in the flower center.