The Genus Machaeranthera
The Tansyasters
Family: Asteraceae
The genus Machaeranthera has about 18 species all of which are native to North America. Tansyasters are variable in appearance. Some are small, singular wildflowers, while others are sprawling shrubs. Several species easily hybridize with each other, as well, making identification difficult.
The genus Machaeranthera is distinguished from the genus Dieteria by having once- or twice-pinnate leaves, whereas Dieteria has entire to toothed leaves. Our two Arizona species are perennials if they have enough water, annuals if resources are low.
Plant in full to part sun, even bright, filtered shade is acceptable. Moderate water is best, if water is scarce, plants will act as annuals. Plants are hardy into the low to mid 20s°F. Plants reseed readily in the landscape, even being on the verge of weedy.
Photo of the Tahoka Daisy (Machaeranthera tanacetifolia) by Sam Kieschnick, iNaturalist
Attracts a variety of pollinators, including bees and butterflies. Larval food plant for the sagebrush checkerspot (Chlosyne acastus), bordered patch (Chlosyne lacinia), the pearl crescent (Phyciodes tharos) and the Brown-hooded Owlet (Cucullia convexipennis).
Machaeranthera species are used medicinally by many people.
Machaeranthera comes from the Greek machaira, meaning sword and anthera or anthers, referring to the shape of the anther-tips.
Floral detail of the Mesa Tansyaster (Machaeranthera tagetina), found on arid mesas, plains, and roadsides from 1,500-4,500', photo by Max Licher, SEINET
Tahoka Daisy (Machaeranthera tanacetifolia), very similar but has broadly turbinate flower heads and phyllaries that can spread a bit but do not curl outward and downward, photo by Ana Sanchez, iNaturalist