Diastrophus fusiformans
Cinquefoil petiole spindle gall wasp

Host: Slender cinquefoil (Potentilla gracilis).

Gall location: On the leaf petiole, although some accounts state that this gall forms on the stem.

Description: Multiple-chambered swellings ranging from 3-10 centimeters in length. Usually spindle-shaped, but often greatly curved or otherwise deformed. Sometimes with fine hairs. Pithy internally, with chambers suspended in the internal pith. Green to red when fresh to brown when dried and old. Similar to the cinquefoil stem spindle gall wasp (see page 39).

Range: Thus far known from Oregon and Washington, but likely far more widespread throughout the range of slender cinquefoil, at least in Western North America.

This gall, like many others, is realtively poorly known. Interestingly, the slender cinquefoil is quite common and widespread, but this gall is only rarely seen.

- Louis Nastasi, Charles Davis: (2022) Field Guide to the Herb and Bramble Gall Wasps of North America^©