Vascular Plants of North Carolina
Account for Arrowleaf Aster - Symphyotrichum urophyllum   (Lindley ex de Candolle) Nesom
Members of Symphyotrichum with account distribution info or public map:
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Section 6 » Order Asterales » Family Asteraceae
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Author(Lindley ex de Candolle) Nesom
DistributionMountains almost exclusively; disjunct to Twelvemile Creek floodplain in Union County. A specimen from Moore County (at USF) is actually S. undulatum.

ME to MN and NE, south to northern FL, MS, and OK.
AbundanceUncommon to infrequent, but perhaps locally common at a few places. Abundance level somewhat unsettled owing to confusion among several similar asters -- S. cordifolium and S. lowrieanum in particular. The State Rank is probably best at S3.
HabitatMesic to moist soils of montane forests and woodlands, streambanks, margins of floodplain forests, openings in the above, roadside banks -- apparently only in rich, circumneutral soil.
PhenologyFlowering and fruiting late August-October.
IdentificationArrowleaf Aster grows mostly 2-3 feet tall, the stem essentially glabrous. Lower leaves are ovate to lanceolate, toothed, long-pointed, cordate-based (heart shape), and with slender stalks. Middle and upper stem leaves become less cordate or not cordate (and often truncate), arrowhead shaped, barely serrated to nearly entire, and generally stalkless but with clasping bases. The inflorescence is composed of short branches that are "clean" looking--they lack the numerous, small, leafy bracts along the branches, as in S. undulatum. From S. cordifolium it differs mainly in the involucral bracts which have a long green stripe (vs. merely a green diamond at the tip in the other species), the rays are usually white (though can occasionally be very pale blue) and not light blue, and middle and upper stem leaves are relatively arrowhead shaped and not widely ovate or cordate. From S. shortii it differs mainly in sharply toothed lower leaves (vs. weakly toothed). S. lowrieanum also has the involucral bracts with a green diamond-shaped mark. These other species tend to have light blue to lavender-blue rays, not white.
Taxonomic CommentsNOTE: The genus Aster was examined by G.L. Nesom (1994), who determined that it was composed of a number of discrete genera (a few of which were already split off by authors as Sericocarpus, Ionactis, etc.). The earliest available name for North American "Aster" is Symphyotrichum, a name regrettably long and hard to spell.

Formerly treated as Aster sagittifolius.

Other Common Name(s)White Arrowleaf Aster
State Rank[S3]
Global RankG4G5
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