Annual Fleabane (Erigeron annuus) vs. Philadelphia Fleabane (Erigeron philadelphicus)

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.

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