| 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 subalpine 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. |
The two Erigerons shown on this page are very similar and appear next to each other in botanical keys. Although the seeds provide a good method for distinguishing between the two (the seeds of E. argentatus have 6-8 veins; those of E. utahensis have 4 veins [rarely 6]), this is not a very noticeable or easy to observe feature. Look first for the basal leaves. As shown in the photographs below, the basal leaves of E. argentatus form a tidy, dense, and often small mound (3-6 inches in diameter). The basal leaves of E. utahensis are often withered at flowering time ("anthesis"), the lower area of the plant looks raggedy, and the basal area is often 6-12 inches in diameter. When you look at the basal leaves also look for dried stems from last year. E. argentatus has no stems from last year; E. utahensis commonly has dried stems from last year. Several other less clear-cut characteristics can sometimes assist in separating the two species: 1) E. argentatus grows at 4,000-7,500 feet in elevation; E. utahensis grows at 3,000-6,000. 2) E. argentatus typically has solitary heads; E. utahensis often has solitary heads but can have few or many. 3) E. argentatus typically grows from 4-12 inches tall; E. utahensis grows from 4-20 inches tall. It is often thought that one key characteristic that separates Erigerons from other genera of Asteraceae is that Erigerons have phyllaries (the bracts that surround the base of the flower head) all in one row. It is worth noting that both species on this page have phyllaries in several rows. |
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Erigeron
argentatus (Silvery Daisy) Asteraceae (Sunflower Family) Semi-desert.
Shrublands. Spring. This silvery ("argentatus") gray-green Erigeron inhabits dry, open lands. It is found in Colorado, New Mexico, and Arizona in just the counties bordering the Four Corners, but it is found in most counties of Utah. It was only found fairly recently on the Ute Mountain Ute Reservation in Colorado by Leslie Stewart. Flowers range from the very pale lavender shown here to much brighter blue-lavender. Several inch long basal leaves are tightly clustered. Stem leaves are fewer and shorter. The plant was named and described in 1873 by Asa Gray from a specimen that his student, botanical associate, and successor, Sereno Watson, found in Nevada. |
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Erigeron argentatus (Silvery
Daisy) Asteraceae (Sunflower Family) Semi-desert.
Shrublands. Spring. The phyllaries are sharply pointed, in three rows, and silvery-strigose (the hairs are thick, sharp-pointed, and appressed). These hairs are also a bit unusual in that they are often bent backward near their tips, i.e., they are "antrorse". You can see this feature along the very left edge of the involucre. |
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Erigeron argentatus (Silvery
Daisy) Asteraceae (Sunflower Family) Semi-desert.
Shrublands. Spring. |
Species present in state and native
Species present in state and exotic
Species not present in state
Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Eradicated
Questionable presence
