Symphyotrichum dumosum var. dodgei (Fernald) G.L.Nesom
Symphyotrichum dumosum var. gracilipes (Wiegand) G.L.Nesom
Symphyotrichum dumosum var. pergracile (Wiegand) G.L.Nesom
Symphyotrichum dumosum var. strictior (Torr. & A.Gray) G.L.Nesom
Symphyotrichum dumosum var. subulifolium (Torr. & A.Gray) G.L.Nesom
Symphyotrichum dumosum (formerly Aster dumosus) is a species of flowering plant of the familyAsteraceae commonly known as rice button aster[3] and bushy aster.[4] It is native to much of eastern and central North America, as well as Haiti and Dominican Republic.[4] It is a perennial, herbaceous plant that may reach a height of 1 meter (3 feet 3 inches).
Symphyotrichum dumosum is a late-summer and fall blooming perennial, with flower heads opening August–October.[5] The flower heads are about 13 millimeters (1⁄2 inch) diameter when in bloom[6] and grow in open and much-branched paniculiform arrays. Each has many tiny florets put together into what appear as one.[5]
Involucres and phyllaries
On the outside the flower heads of all members of the family Asteraceae are small bracts that look like scales. These are called phyllaries, and together they form the involucre that protects the individual flowers in the head before they open.[a][7] The involucres of Symphyotrichum dumosum are cylinder-bell in shape and usually 4.5–6.3 mm (1⁄5–1⁄4 in)[b] long.[5]
The phyllaries are appressed or slightly spreading. The shape of the outer phyllaries is oblong-oblanceolate or linear-oblanceolate, and the innermost phyllaries are linear. They are in 4–6 strongly unequal rows, meaning they are very staggered and do not end at the same point, and they are hairless.[5]
Florets
The 15–33 ray florets are blue, pink, purple, or white, with a length averaging 5–7 mm (1⁄5–3⁄10 in)[c] and width of 1–1.7 mm (1⁄24–1⁄16 in).[5] Ray florets in the Symphyotrichum genus are exclusively female, each having a pistil (with style, stigma, and ovary) but no stamen; thus, ray florets accept pollen and each can develop a seed, but they produce no pollen.[8]
The 15–30 disk florets start out as pale yellow and turn pink with age. They are in the shape of a narrow funnel and are shallow at 3.5–4.5 mm (3⁄20–1⁄5 in) in depth. The disk florets are each made up of 5 petals, collectively a corolla, which open into 5 lanceolate lobes[d] comprising less than 25% of the depth of the floret.[5] Disk florets in the Symphyotrichum genus are bisexual, each with both male (stamen, anthers, and filaments) and female reproductive parts; thus, a disk floret produces pollen and can develop a seed.[8]
Flower head showing ray and disk florets
Involucre, phyllaries, and bracts
Involucre, phyllaries, and bracts
Chromosomes
Symphyotrichum dumosum has a chromosome number of x = 8.[9]Diploid and tetraploidcytotypes with respective chromosome counts of 16 and 32 have been reported.[5]
Taxonomy
This species was long known as Aster dumosus before it was moved into its current genus due to a phylogenetic analysis performed by American botanist Guy L. Nesom.[10] The genus Aster has been narrowed considerably in scope in recent years, due to new information about the relationships of the species in the group.[11]
Symphyotrichum dumosum is classified in the subgenusSymphyotrichum, sectionSymphyotrichum, subsection Dumosi.[12] It is one of the "bushy asters and relatives."[9] The word Symphyotrichum has as its root the Greek symph, which means "coming together," and trichum, which means "hair."[13] The specific epithet (second part of the scientific name) dumosum is Latin neuter case of dumosus and means "full of thornbushes" and "bushy" (rare).[14]
Symphyotrichum dumosum is categorized on the United States National Wetland Plant List (NWPL) with Wetland Indicator Status Rating of Facultative (FAC), choosing wetlands or non-wetlands and adjusting accordingly.[18]
Conservation
As of July 2021[update], NatureServe lists Symphyotrichum dumosum as Secure (G5) worldwide with notation that the global status was last reviewed in 1985. Some North American province and state statuses are as follows: Presumed Extirpated (SX) in Iowa, Possibly Extirpated (SH) in Maine, Critically Imperiled (S1) in Pennsylvania, Imperiled (S2) in Ontario and Ohio, and Vulnerable (S3) in New York and Florida.[1]
Morhardt, S.; Morhardt, E. (2004). California desert flowers: an introduction to families, genera, and species. Berkeley, Los Angeles, and London: University of California Press. ISBN0520240030.
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