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     Erigerons, commonly called "Daisies" or "Fleabanes", are a large and complex genus.  This web site shows 24 of the 48 species in the Four Corners area;  there are 130 species in North America and 200 world-wide.

     Erigerons have yellow disk flowers and numerous narrow ray flowers that are white, pink, or purple (but not yellow).  They grow from the semi-desert to the alpine regions and although a few are uncommon, most are very common.

      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.

Erigeron coulteri
Erigeron coulteri (Coulterís Daisy)
Asteraceae (Sunflower Family)

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

Coulterís Daisy is common in high mountain dry and moist meadows and open Spruce woods.  It grows singly, scattered in large patches 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.  Click to see a common August mountain meadow.

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 about Coulter.)

Erigeron coulteri

Erigeron coulteri

Erigeron coulteri

Erigeron coulteri (Coulterís Daisy)
Asteraceae (Sunflower Family)

Subalpine. Meadows, woodlands. Summer.
Colorado Trail above Roaring Fork, July 26, 2004.
Turkey Springs Trail, June 26, 2007
Calico Trail, August 25, 2014.

As the top photograph at left shows, Erigerons can unfold in a rather cute and even 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. Compare these hairs (and other plant characteristics) with those of Erigeron elatior.  

Note the presence of both light and dark hairs on the flower stem and phyllaries of E. coulteri.  Most botanical keys indicate that these hairs have "black crosswalls" and that these black crosswalls are key in separating E. coulteri from other species. But the crosswalls (which under high magnification appear as horizontal rings around the vertical hairs) are very difficult to observe in the field --  even with a 10x hand lens. There really are much better and much more obvious distinguishing characteristics, e.g., the leaf shape or the intense whiteness of the ray flowers or the relatively upright and short nature of E. coulteri's hairs versus the tangled masses of hairs on E. elatior [which E. coulteri is usually compared to in our area).

At twenty-to-forty power magnification with a microscope, one can see that most phyllary hairs do have crosswalls, but they are white as well as black. Some hairs are completely dark (maroon to black); some hairs are dark on the bottom and a gelatinous white on the top; some are completely white; etc. Are we really supposed to see black crosswalls on a black hair?

I am curious about who started the use of crosswalls to distinguish E. coulteri, so I tried to track down the first "black crosswalls" reference in a botanical key. Interestingly, that reference is not in the original 1874 description of the plant by Porter and Coulter, nor is it in Rydberg's Flora of Colorado published in 1906. Sometime after this there must be some key that used the "black crosswall" characteristic as crucial and then that characteristic was picked up by botanists for their keys.

The use of the "black crosswall" characteristic is even more convoluted than I describe above. The first reference that I can find to these walls is in Harrington's Manual of the Plants of Colorado published in 1954, and interestingly and to Harrington's credit, he indicates "black crosswalls near their base", which is a pretty accurate description. But the "near the base" words have been picked up by just a few floras after Harrington's Manual. That omission makes it appear that we should be looking for the black crosswalls throughout the length of the hairs. F

Erigeron coulteri

Erigeron eatoni
Erigeron eatonii (Eaton's Fleabane) 
Asteraceae (Sunflower Family)

Foothills, montane. Meadows, Oak brush. Spring, summer.
Mesa Verde National Park, May 29, 2013.

Erigeron eatoni

Erigeron eatoni 

Erigeron eatonii (Eaton's Fleabane) 
Asteraceae (Sunflower Family)

Foothills, montane. Meadows, Oak brush. Spring, summer.
Northeast corner of Navajo Reservation, June 3, 2006; Mesa Verde National Park, May 29, 2013; and Robertson Pasture Trail, Abajo Mountains, Utah, May 31, 2016.

Erigeron eatonii's flowering stems arch outward and then upward from a central base. One, or more commonly, three-nerved, grass-like basal leaves also arch, but usually outward and then downward.

Erigeron eatonii

 

Erigeron eatonii is most often found in sagebrush country but it is also occasionally found at higher elevations. Flowerheads are about a half-inch in diameter.

Asa Gray named this plant in 1880 from a specimen collected by Sereno Watson in Utah.  Daniel Eaton was a 19th century Professor of Botany at Yale. (More biographical information about Eaton.)

Erigeron eatoniErigeron eatoni
Erigeron eatonii (Eaton's Fleabane) 
Asteraceae (Sunflower Family)

Foothills, montane. Meadows, Oak brush. Spring, summer.
Northeast corner of Navajo Reservation, June 3, 2006.

Phyllaries, stems, and white-veined leaves are covered in sharp, mostly straight, and mostly appressed hairs (strigose hairs). Leaves most commonly have three nerves but, as in the above left photograph, they can have one nerve.

The photograph at left shows an outer ring of central disk flowers open and yellow; the inner flowers are closed and green but will open over a few days. In the above left photograph the central flowerhead has more disk flowers open and yellow. Some of the yellow corollas and pollen may also be from the one-petaled outermost ring of ray flowers.

Ray flowers are fewer (20-50) in E. eatoni than in other species of Erigeron that flower at the same time and that might be confused with E. eatoni. (See, for example, Erigeron flagellaris which has 50-100 ray flowers.)

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 eatonii

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