Blue Tansy

Phacelia tanacetifolia is a species of flowering plant in the family Hydrophyllaceae, known by the common names lacy phacelia, tansy-leaf phacelia, blue tansy, purple tansy or fiddleneck (UK).

Etymology: Phacelia is derived from Greek and means ´bundle´, in reference to the clustered flowers, while tanacetifolia means ´with leaves resembling those of Tanacetum.´

 Phacelia tanacetifolia is an annual that grows erect to a maximum height near with none to a few branches. The wild form is glandular and coated in short stiff hairs. The leaves, , are mostly divided into smaller leaflets which are deeply and intricately cut into toothed lobes, giving them a lacy appearance. The dense and hairy inflorescence is a one-sided curving or coiling cyme of bell-shaped flowers in shades of blue and lavender. Each flower is just under a centimeter long and has protruding whiskery stamens.

The seeds are "negatively photoblastic", or photodormant, and will only germinate in darkness.

Beneficial insects: Phacelia tanacetifolia is native to the Southwestern United States and northwestern Mexico. It is most common in the deserts of southern California at elevations below , but may be occasionally found at much higher elevations.

It is used outside its native range in agriculture as a cover crop, a bee plant, an attractant for other beneficial insects, as a green manure and an ornamental plant. It is planted in vineyards and alongside crop fields, where it is valued for its long, coiling inflorescences of nectar-rich flowers which open in sequence, giving a long flowering period. It is a good insectary plant, attracting pollinators such as bumblebees and honey bees.

Biological pest control: It is also attractive to hoverflies (family Syrphidae), which are useful as biological pest control agents because they eat aphids and other pests.