Plants of the Eloise Butler Wildflower Garden

White Arrowleaf Aster is a native perennial aster growing from 1 to 4 feet in height, unbranched below the floral array. The stems are green initially and may have fine white hair, particularly within the array. Stems take on a reddish tone in full sun.

Leaves: Leaves vary considerably depending on position. Middle stem leaves have a narrowly heart shaped to truncate base, with a lanceolate shape blade, somewhat arrow shaped providing the common name; these usually have a winged stalk. Lower basal leaves will usually have heart shaped bases, a long stalk with less of a wing and usually drop off by flowering time. Upper leaves can be stalkless or have a short winged stalk - these are less likely to look arrow shaped. Leaf edges vary from entire to a few small teeth to a number of coarse teeth. The underside of the leaf is of paler color with fine white hair on the mid-rib and some of the larger veins.

The floral array is a open branched panicle, taller than wide, with branches tending upward, usually crowded with racemes of flower heads. Plants growing in full sunlight will have tighter, more narrowly cone-shaped flower racemes whereas in those plants with less sun, the racemes will be more broad.

Flowers: Individual flowers are small, up to 1/2 to 3/4 inch wide, but usually 1/2 or slightly less. Flowers have two types of florets: Ray florets with 8 to 15 rays that can be colored from white to pale blue. These are pistillate and fertile. These surround about 10 to 15+ tubular disc florets that have light yellow corollas when young, but like most aster florets in this genus, turn reddish-purple toward maturity. The yellow lobes of the disc corolla tube do not flare outward at the apex like those of many other asters but, instead, bend inward a bit. Anthers of the five stamens are darker colored and appressed against the style, which with an appendage on top, is exserted from the corolla at flowering time. Phyllaries of the flower head are long and narrow in 4 to 6 series, those of the inner series appressed, the outer lower ones outward spreading. They are light colored with a green tip in the shape of an elongated diamond. Tips can also take on a purplish tint. There is usually several small linear leafy bracts subtended to each flower head which grade into the phyllaries.

Seed is a small dry 4 to 6 nerved brown or purple obovoid shaped cypsela, 1.8 to 2.5mm long, with a whitish pappus for wind distribution. Some species of the Symphyotrichum genus have seeds that may require at least 30 to 60 days of cold stratification for germination and in addition seeds of this genus are small and need light for germination so they should be surface sown.

Habitat: White Arrowleaf Aster grows from a rhizomatous root system with stout branched caudices, in partially sunny spots that are not overly moist - wood edges, disturbed soils, roadsides. The plant readily self-seeds.

Names: The older scientific name for this aster is Aster sagittifolius. All the new world asters, formerly in the genus Aster, have now been reclassified, most into the genus Symphyotrichum. The genus name is from the Greek symphysis, for 'junction', and 'trichos', for hair and, while obscure, it was first applied by Christian Gottfried Daniel Nees von Esenbeck in the 1800s in describing the type aster for the genus. The species urophyllum, means 'leaves with a tail-like tip' - which in this case is a bit dense but probably refers to the small whip-like tip of the larger leaves (see photo below). The old species name referred to the arrow shape leaves which was a bit more straight-forward. The author names for the plant classification are as follows: ‘Lindl.’ is for John Lindley (1799-1865), English botanist who authored or co-authored a number of articles and books on plants, some with his own colored engravings; he was particularly interested in roses and orchids, an active member of the Royal Horticultural Society and a University professor. His work on this species was revised by ‘G. L. Nesom’ who is Guy L. Nesom (b. 1945) American botanist who has published papers on the nomenclature of asters.

Comparisons: The small flowers and conical floral array resemble the Heart-leaved Aster, Symphyotrichum cordifolium, but there the leaves are heart-shaped with coarser teeth and a narrower stalk. Closest in overall style is The White Panicle Aster, Symphyotrichum lanceolatum, which has a bushy panicle of many flowers also, but the flowers can be twice the size, the plant is taller and the leaves are linear to lance-like. See photo comparison below.