In 1753 Linnaeus gave the genus its name from the Greek "eri" ("early") + "geron" ("old man", as in "geriatrics", the study of old age processes and problems).  Perhaps the Greek name refers to characteristics of some now unknown plant or perhaps it refers to the early flowering of many species and to the bristly pappus of the developing seed, or perhaps to the puffy, grizzled appearance of the mature seed head.

Subalpine. Meadows, woodlands. Summer.
Middle Calico Trail, August 9, 2004.

Coulter’s Daisy is common in high mountain dry and moist meadows and open Spruce woods.  It grows singly and widely scattered in open woods or more densely in sunny open meadows.  Each plant generally bears one long-lasting flower.  Basal leaves are often withered by flowering time.  In late July, August, and into September, Erigeron coulteri is one of the most common white flowers in the mountains.

John Coulter collected this plant in Colorado and it was described and named for him by Thomas Porter who, with Coulter, in 1874 authored the first Colorado floral guide, Synopsis of the Flora of Colorado.  (More biographical information.)

Subalpine. Meadows, woodlands. Summer.
Colorado Trail above Roaring Fork, July 26, 2004.
Turkey Springs Trail, June 26, 2007.

Erigerons often unfold in a humorous fashion.   The bright white ray flowers in the first two photographs contrast sharply with the dark hairs on the phyllaries on the underside of the flower.  

Note the presence of both light and dark shaggy hairs on the flower stem and phyllaries in the third photograph.  Most botanical keys indicate that Erigeron coulteri hairs have "black crosswalls".  These crosswalls (under high magnification they appear as horizontal rings around the vertical hairs) really cannot be observed in the field --  even with a 10x hand lens.  At twenty-to-forty power magnification with a microscope, one can see that some hairs are dark (maroon-black); some hairs are dark on the bottom and a gelatinous white on the top; some are white with black crosswalls; some are dark from bottom to top; etc.  Most do have black, or sometimes white, crosswalls.

Phyllaries, stems, and white-veined leaves are covered in sharp, mostly straight, and mostly appressed hairs.

Range maps © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Erigeron coulteri

Range map for Erigeron eatoni