White Arrowleaf Aster

Appearance

Symphyotrichum urophyllum is a perennial herbaceous species between 40 to 120 cm tall. Plants are cespitose, with 1-5 erect stems emerging from the same point. The broad, thin, toothed leaves are arrow-shaped, with a broadly winged petiole. The dense, pyramidal inflorescence of composite flowers is distinctive. The ray florets are white and the disc florets are white to cream becoming pink.

Basal and proximal leaf blades 15–50 mm wide, bases usually shallowly, sometimes deeply cordate to truncate or rounded (proximal sometimes attenuate), distal leaves ± shortly winged-petiolate or sessile; array branches stiffly ascending to erect.

Naming

Symphyotrichum urophyllum (Lindley ex de Candolle) G. L. Nesom
Aster urophyllus Lindley ex de Candolle
Aster sagittifolius Wedemeyer ex Willdenow var. dissitiflorus E. S. Burgess

White Arrowleaf Aster has a history of taxonomic instability. It has been regarded as a variety of Symphyotrichum cordifolium (Heart-leaved Aster) and Symphyotrichum sagittifolium (Arrow-leaved Aster) in the past. It is also similar to Symphyotrichum drummondii (Drummond's Aster). Some taxonomists consider Symphyotrichum sagittifolium to be a synonym for Symphyotrichum urophyllum, however A.G. Jones (1989) ultimately separated them taxonomically. White Arrowleaf Aster can be considered distinct from the preceding aster species in this group by the following characteristics: 1) the petaloid rays of this aster are usually white, rather than lavender, 2) the alternate leaves of this aster tend to be more narrow in shape, 3) the phyllaries of this aster have midsections that are dark green and linear in shape throughout their length, rather than narrowly diamond-shaped and dark green toward their tips, and 4) the phyllaries of this aster tend to have tips that are more tapered and stiff. White Arrowleaf Aster is also less hairy than Drummond's Aster. A scientific synonym of White Arrowleaf Aster is Aster urophyllus.

Distribution

Symphyotrichum urophyllum is native to the United States from Maine to Florida and west to Nebraska, and to Ontario, Canada.

Status

Listed in Vermont as extremely rare (S-rank: S1).

Habitat

Symphyotrichum urophyllum is found in open, dry to mesic habitats such as meadows, open woodland, bluffs, forest edges and roadsides.

Reproduction

Seeds and by short rhizomes.