Arrow-leaved Aster
Symphyotrichum urophyllum
(formerly Aster sagittifolius)

Arrow-leaved Aster (Symphyotrichum urophyllum) Other common names: White Arrowleaf Aster

Other scientific names: Aster sagittifolius, Aster hirtellus, Aster urophyllus

Family: Composite Family (Asteraceae)

Group: Asters

Distinctive features: Leaves are sort of arrow-shaped, without a deep cleft at base. Branches sweep upward, close to main stem.

Similar species:
  •   Heart-leaved Aster (Symphyotrichum cordifolium) - Leaves larger and more heart-shaped.

  •   Calico Aster (Symphyotrichum lateriflorum) - Same habitat, smaller plant, horizontal branches, smaller leaves.

  •   Large-leaved Aster (Eurybia macrophylla) - In the woods; flower head is flat-topped; leaves are much larger.

  •   Azure Aster (Symphyotrichum oolentangiense)


Flowers: Summer, Autumn;  White;  7 or more parts (petals);  1.5cm in diameter. Ray flowers: 8-15, usually white, sometimes pale pink or bluish. Disc flowers: 8-20, yellow becoming purple. Flower heads are a panicle shape. Many flowers are arrayed along upward sweeping branches.

Leaves: Alternate, Simple;  Sparse, arrow-shaped, but in the form of a spear point, not the form of -> or <-. Narrowly egg-shaped and shallowly toothed. Leaf stalks (petioles) winged. Lower leaves may be somewhat heart-shaped. Lower leaves are the largest.

Height: 40-100 cm (15-39 in)

Stem: Smooth to somewhat hairy. Side branches are upward sweeping.

Habitat: Fields and Open Areas, Meadows;  Forest edges or dry open areas of woods. Widely distributed in southern Ontario.

Grows in Sun/Shade: Sun

Lifespan: Perennial.  

Books: Newcomb's Wildflower Guide: 454    Peterson's Field Guide to Wildflowers: 354   

Native/Non-native: Native

Status: Very common.

Notes: This Aster grows on the edges of forests. It is most easily confused with Heart-leaved Aster (Symphyotrichum cordifolium), which often grows very near or in the same area. It can also be confused with Calico Aster (Symphyotrichum lateriflorum) by the novice.

For more information visit: Ontario Wildflowers

Photographs: 155 photographs available, of which 18 are featured on this page. SCROLL DOWN FOR PHOTOGRAPHS.

Range Map is at the bottom of the page

Arrow-leaved Aster (Symphyotrichum urophyllum)

Typical Arrow-leaved Aster with upswept stems and white flowers.

Arrow-leaved Aster (Symphyotrichum urophyllum)

Note the branches that sweep up and remain close to the plant. This is in contrast to Calico Aster (Symphyotrichum lateriflorum), with which Arrow-leaved Aster is sometimes confused.

Arrow-leaved Aster (Symphyotrichum urophyllum)

Arrow-leaved Aster (Symphyotrichum urophyllum)

A closer look at the flowers. Note they are typical Aster flowers in that the discs start out yellow, gradually turning purple as they age.

Arrow-leaved Aster (Symphyotrichum urophyllum)

A closer view of flowers.

Arrow-leaved Aster (Symphyotrichum urophyllum)

Arrow-leaved Aster (Symphyotrichum urophyllum)

An entire plant.

Arrow-leaved Aster (Symphyotrichum urophyllum)

A plant with smaller upswept stems.

Arrow-leaved Asters like to grow at the edge of woods and fields.

Arrow-leaved Aster (Symphyotrichum urophyllum)

The leaves which give this plant its name.

Note that the "arrow" aspect is an arrow without a very deep cleft at the base of the arrowhead (in the world of botany that cleft is referred to as a "sinus").

The upper surface.

Arrow-leaved Aster (Symphyotrichum urophyllum)

Another leaf.

Arrow-leaved Aster (Symphyotrichum urophyllum)

The underside of the leaf.

Arrow-leaved Aster (Symphyotrichum urophyllum)

Basal leaves.

Arrow-leaved Aster (Symphyotrichum urophyllum)

A leaf attached to the plant.

Arrow-leaved Aster (Symphyotrichum urophyllum)

A worn leaf, in September.

Arrow-leaved Aster (Symphyotrichum urophyllum)

The lower leaves are usually dried up by the time this plant is flowering.

Arrow-leaved Aster (Symphyotrichum urophyllum)

The upper stem has many smaller, non-arrow-shaped leaves, sort of like Heart-leaved Aster (Symphyotrichum cordifolium).

Arrow-leaved Aster (Symphyotrichum urophyllum)

Stem.

Arrow-leaved Aster (Symphyotrichum urophyllum)

Going to seed in early October.


Range map for Arrow-leaved Aster (Symphyotrichum urophyllum)

PLEASE NOTE: A coloured Province or State means this species occurs somewhere in that Province/State.
The entire Province/State is coloured, regardless of where in that Province/State it occurs.

(Range map provided courtesy of the USDA website and is displayed here in accordance with their Policies)

 

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