There are a number of species of Fleabanes. They all have numerous rays of various colors surrounding a flat yellow disc. They are either annual, biennial or perennial and with the number of different species, they can be in flower from late spring to fall.
Philadelphia Fleabane is the most common Fleabane in Minnesota. It is a native, erect biennial to perennial growing on green hairy stems from 1/2 to 3 feet high. Stems have fine ridges and usually branch only in the floral array. Stem hair is soft, usually long and spreading.
The leaves are both basal and stem. Basal leaves are a widened lance-shape (obovate), with a rounded tip, the margins have coarse teeth, sharp to rounded, with either sparse fine hair or none on the leaf surface. These may sometimes drop away at flowering time, but are usually present in our area. The stem leaves are alternate, more narrowly lance like with sparse teeth. Those near the top are reduced in size and may have entire margins. Stem leaves are without stalks and clasp the stem or at least have an auricle that clasps. The leaf surface has hair or fine projections resembling hair.
The floral array is a branched cluster atop the stem with 3 to 35 stalked heads, usually more than 9.
Flower heads are composite, 1/2 to 3/4 inch wide and have two types of flowers - an outer ring of 150 to 250 (400) ray florets, 5-10 mm long, that are pistillate only, but fertile, with pale yellow styles. These usually have white rays but they can range into pinkish. The ray florets surround the flat inner disc of numerous disc florets which are bisexual and fertile. The disc florets have tubular yellow corollas that have a five-lobed lip. The five stamens of the disc florets have dark brown anthers which tightly surround the single style; both style and stamens are exserted from the corolla throat when the floret opens. These disc florets open from the outside of the disc toward the center and turn a darker color as they open. Around the outside of the flower head are 2 to 3 series of phyllaries that can be smooth to having fine hair, sometimes minutely glandular. Flower stalks have hair. Open flowers close at night.
Seed: Fertile disc florets produce a dry narrow pyramidal shaped seed (a cypsela) that has a fluffy pappus for dispersion by the wind. If the outer rays florets form seed, they have stiff hair attached, not a fluffy pappus.
Habitat: Philadelphia or Common Fleabane is a biennial/perennial and requires moist soil and full sun to grow best, but it will tolerate a variety of soils and partial shade. Pollination is by butterflies, moths and bees. It can be invasive in certain conditions so if you plant it, watch for excessive seed germination. The biennial grows from a fibrous root system with simple caudices. Perennial plants produce stolons and offsets to form new plants.
Names: The genus name, Erigeron, is derived from two Greek words, either eri, meaning 'early' or erio, meaning 'woolly', and geron, meaning 'old man'. Thus a flower that has early flowers and gray to whitish seed heads, which in some species of Erigeron look woolly white like the head of an old man (more notes below). The species name, philadelphicus, refers to 'of Philadelphia'. The accepted author name of the plant description classification, from 1753 - 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: For a comparison of the three Fleabanes found in the Garden see this page - Fleabanes.
Above: Philadelphia Fleabane flower heads have 150 to 250+ individual ray florets that are pistillate only (styles visible in 2nd photo). In the flat central disc are numerous bisexual disc florets that have tubular yellow corollas that have a five-loped lip. These open from the outside toward the center and turn a darker color as they open.
Below: The disc florets produce a dry narrow pyramidal shaped cypsela that has a fluffy pappus for dispersion by the wind.
Below: 1st photo - The outside of the flower head has 2 to 3 series of phyllaries that can be smooth to having fine hair, sometimes minutely glandular. Flower stalks have hair. 2nd photo - The basal rosette of leaves formed the first year of the plants biennial cycle.
Below: 1st photo - The floral array branches into multiple flower heads. The main stem may branch at the top into several array branches. 2nd and 3rd photos - The stem and stem leaves are hairy with the leaf clasping the stem - either entirely or with a pair of auricles as shown here - this is unlike the other 2 fleabanes in the Garden. 4th photo - Lower stem leaves are larger and toothed but may lack as much hair as the upper stem leaves.
Below: 1st photo - The green hairy ridged stem. 2nd photo - The upper surface of an upper stem leaf showing the surface and edge hair. 3rd photo - A basal leaf with its long winged stalk. Edges are usually lobed instead of toothed and mostly hairless.
Notes: Philadelphia Fleabane is found throughout the United States except for Utah and Arizona, and is found in most of Canada. In Minnesota, it is the most widely spread of the Erigerons and has been reported in all counties except Traverse. Curiously, it is not considered indigenous to the Garden as Eloise Butler did not record its presence. Martha Crone did include it on her 1951 Garden census. There are three accepted varieties of E. philadelphicus only the first of which is considered native to Minnesota: E. philadelphicus var. philadelphicus, where the stem leaf upper surface is sparsely hairy or covered with short projections; the other two have surfaces generally smooth; var. glaber where the basal leaves are withering by flowering time; and var. provancheri where the basal leaves are present by flowering time.
There are 7 species of Erigeron found in Minnesota: E. acris, Bitter Fleabane (on the State Special Concern List); E. annuus, Eastern Daisy Fleabane (or Annual Fleabane); E. glabellus, Streamside or Smooth Fleabane; E. lonchophyllus, Short-ray Fleabane (on the State Special Concern List); E. philadelphicus var. philadelphicus, Philadelphia Fleabane; E. pulchellus - in two varieties, Robin's-plantain (or Fleabane); and E. strigosus, Prairie or Daisy Fleabane - in two varieties.
There is native medicinal use of the plant reported for various groups, particularly the Cherokee and Houma, who used the roots and leaves.
The common name of 'Fleabane' might imply that the plant repels fleas, yet there is little literature confirming this. North American species of Erigeron, particularly E. canadense, (now reclassifed to Conyza canadensis), were imported to Europe and used for medicinal purposes. Culpepper (Ref. #4b) wrote that the name is due to the seeds of the fleabanes which are as small as fleas. Mrs. Grieve (Ref. # 7) writes that Erigeron denotes 'soon becoming old' as is appropriate for a genus where many species have a worn-out appearance, even when still in flower.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"