Aster anomalus Engelm. - Soft Blue Aster

Aster anomalus plant

Family - Asteraceae

Stems - To -1m tall, erect, herbaceous, terete, from a slightly elongated woody caudex and slightly thickened roots, puberulent (the trichomes multicellular), somewhat scabrous, green, typically simple at the base, widely branching in the apical 1/2 (the inflorescence).

Aster anomalus rootCaudex and roots.

Aster anomalus stemPortion of upper stem.

Leaves - Alternate, petiolate. Basal rosette leaves similar to cauline leaves. Petioles to +/-4cm long, puberulent as the stem, narrowly winged by decurrent blade tissue. Wings 1mm or less broad, forming an adaxial groove on the petiole. Blades ovate to lanceolate, cordate to truncate at the base, entire or with a few coarse teeth, attenuate, to 8-9cm long, 3-4cm broad, slightly reduced upward. Leaves in inflorescence reduced to linear bracts and typically somewhat recurved. Blades soft puberulent, more so abaxially (again with multicellular trichomes).

Aster anamolus leaves

Inflorescence - Single flower heads terminating branches of the inflorescence. Flowers of the inflorescence typically open and sparse but sometimes dense as seen below:

Aster anamolus inflorescence

Involucre - Cylindric, 7-8mm long (tall), 5-7mm in diameter. Phyllaries imbricate, linear, strongly recurved, puberulent, 5-8mm long, +/-1mm broad, green, with a callous translucent bristle tip. Tip to .4mm long.

Aster anamolus involucreInvolucre.

Ray flowers - +/-23 per head, fertile, pistillate. Corolla tube to 4mm long, white, mostly glabrous externally or with a few appressed hairs. Ligule lilac, +/-1.6cm long, -3mm broad, glabrous or with a few appressed hairs at the base abaxially. Style white, glabrous, +/-5mm long, yellow at the apex, bifurcate. Stigmas to 1.2mm long. Pappus of numerous capillary bristles. Bristles white, antrorse barbellate, +/-4mm long.

Disk flowers - Disk 5-6mm broad. Corollas 5-6mm long, contracted and white in the basal 1/2, expanded and yellow in upper 1/2, glabrous inside and out, 5-lobed. Lobes acute, spreading, .7mm long. Stamens 5, adnate at the apex of the constricted portion of the corolla tube. Filaments translucent, +/-2mm long, terete. Anthers yellow, 1.3mm long, partially to entirely exserted, connate around the style. Style white, terete, glabrous, 5-6mm long. Stigmas yellow, 1mm long, not spreading, pubescent at the apex. Achenes of rays broader than those of disk flowers, glabrous, white, compressed, with 5 thick and evident veins (ribs). Receptacle flat, naked.

Aster anomalus flowers

Flowering - July - November.

Habitat - Dry and rocky open woods, thickets, roadsides. Typically on acid soils.

Origin - Native to U.S.

Other info. - This showy species is one of the most common blue-flowered Asters in the Ozark region and in Missouri. The plant can be seen in profusion along roadsides through the Ozarks and is found in nearly all the upland wooded habitats there. It is, however, absent from the extreme southeast and northwest corners of the state.
This species can be differentiated from the other blue-flowered Asters because of its soft pubescent leaves and recurved phyllaries. The leaves of other species have a scratchy texture to them. A. anomalus has just about the softest leaves of them all. If you are in doubt about which cordate-leaved Aster you are looking at, just remember - "There is nothing softer than anomalus." The narrowly-winged petioles also help to ID this species. Other similar Asters have much broader wings on their petioles.

Photographs taken in the Ozark Scenic Riverways, Shannon County, MO., 9-21-03.


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