Flora Pittsburghensis

Pittsburgh Pest (Galinsoga parviflora)

Galinsoga parvifloraPhotographed June 27.

Obviously this is not known as Pittsburgh Pest everywhere in its nearly global range, but the name seems to be well established here, and it is frequently used elsewhere in the United States. It has many other names in English, including the delightful folk etymology “Gallant Soldiers.” It comes originally from South America, where it is a popular ingredient in Colombian and Bolivian cuisine.

The flowers are like tiny five-rayed daisies; the plant is low and hairy, and can grow from any crack in the pavement. It is very much an urban weed, ubiquitous in the city of Pittsburgh, but much rarer in the near suburbs, and unknown in all the other counties of the metropolitan area but one (Washington County).

Galinsoga parviflora

Gray describes the genus and the species:

GALINSÒGA R. & P. Heads several-flowered, radiate; rays 4-6, small, roundish, pistillate. Involucre of 4-5 ovate thin bracts. Receptacle conical, with narrow chaff. Pappus of small oblong cut-fringed chaffy scales, sometimes wanting. — Annual herbs, with opposite triple-nerved thin leaves, and small heads; disk yellow; rays white or reddish. (Named for Dr. Mariano Martinez de Galinsoga, a Spanish botanist.)

Rays white; pappus of disk-flowers about equaling the achenes.

G. parviflòra Cav. Pubescence subappressed; leaves ovate, crenate-serrate, petioled; pappus of the disk-flowers of spatulate obtusish scales.— Roadsides and waste places, from N. E. across the continent. (Adv. from Trop. Am.) Var. Híspida PC. Pubescence more copious, not appressed; pappus-scales of the disk-flowers attenuate and bristle-tipped. — Me. to Ont., Wise., and southw. (Nat. from Trop. Am.)

Galinsoga parviflora

Galinsoga parvifloraPhotographed July 16.

Family Compositae or Asteraceae (Composite Family).   |   Index of Families.