This photo is featured in 3 plant ID/comparison guides:
These two species are usually easy to tell apart whether or not flowers are present, as they have major differences in flower structure as well as leaf shape and stem pubescence. E. philadelphicus prefers moister habitats, whereas E. strigosus prefers drier habitats with less competing vegetation, but ranges farther in all directions.
These two species can be confused, as both have abundant basal leaves and clasping leaves along the stem, both can be found in lightly-shaded habitats, and they have overlapping bloom times. They are easily distinguished by flowers, and they also have little overlap in habitat, although differences in habitat may require close observation. E. philadelphicus has a broader range, is more common and widespread, and is found in a wider range of habitats, preferring moister, more disturbed habitats with richer soils, tolerating poor drainage, and ranging into full sun. E. pulchellus is more restricted to drier, less-disturbed, lightly-shaded habitats, in soil of low fertility.
These visually-similar species often occur together in the same habitat. Flowers can be distinguished by width and count of rays; leaf bases clasp the stem on E. philadelphicus but not on E. annuus. There are other major differences in leaves and growth habit, but the variability of both species makes these characteristics trickier to rely on for identification. On average, E. philadelphicus blooms earlier, but both species have variable bloom times. E. annuus ventures into slightly drier and slightly more disturbed sites, and usually cannot survive in mowed lawns, whereas E. philadelphicus is more restricted to moist sites and is more likely to persist in lawns.
