Symphyotrichum patens (Aiton) G.L. Nesom

Spreading Aster

Symphyotrichum patens plant

Family - Asteraceae

Stems - To 1m tall, herbaceous, branching in apical 1/2, moderately antrorse pubescent (densely in inflorescence), erect, from rhizomes and thickened roots, terete.

Symphyotrichum patens stemStem.

Leaves - Alternate, sessile, clasping, auriculate. Internodes below the inflorescence 2-3cm long. Blades entire, acute, oblong, to +6cm long, 1.5-2cm broad, scabrous, sparse pubescent above, more so below. Leaves greatly reduced in inflorescence to bracts. Lower cauline leaves typically dried by anthesis.

Inflorescence - Terminal flower heads in a loose paniculate arrangement. Peduncles long, with greatly reduced leaves, striate.

Involucre - Cylindric, to 5-6mm long, 4-5mm in diameter. Phyllaries imbricate, glandular pubescent and puberulent, just the apices spreading and often reddish-purple, glabrous internally in the basal 2/3, with scarious margins and a green midrib, acuminate, 4-5mm long, 1-1.2mm broad, linear-oblong.

Symphyotrichum patens involucreInvolucre.

Ray flowers - Flowers 15-20 per head, fertile, pistillate. Ligules blue, to +1cm long, 2-2.5mm broad, minutely 3-lobed at apex (use a lens to see), glabrous. Corolla tube pubescent, whitish, 4-5mm long. Style exserted from beyond the corolla tube, white, glabrous. Stigmas yellow, 1.1mm long. Achenes quadrangular, white, densely retrorse ciliate, 1mm long in flower. Pappus of barbellate capillary bristles to 5mm long. Bristles tan to cinnamon.

Disk flowers - Disk 5-9mm broad. Corolla pale yellow, to 6mm long, glabrous, 5-lobed. Lobes acute, mostly erect, .8mm long, yellow. Stamens 5, slightly exserted, adnate at the base of the corolla tube. Filaments thin, glabrous, translucent. Anthers yellow to tan, to 2mm long, connate around the style. Style bifurcate, exserted slightly beyond the anthers, glabrous, translucent. Stigmas yellow, slightly compressed, 1.5mm long, pubescent in apical 1/2. Achenes and pappus as in ray flowers. Receptacle flat, naked.

Symphyotrichum patens flowers

Symphyotrichum patens flowers

Flowering - August - October.

Habitat - Rocky and sandy open woods, thickets, glades.

Origin - Native to U.S.

Other info. - This attractive species can be found in the southern 1/2 of Missouri. The plant is fairly easy to ID (for a Symphyotrichum) because of its big blue flower heads and hairy stems, which have long internodes. Symphyotrichum novae-angliae L. is similar but has much shorter internodes and flower heads with many more ray flowers. S. oblongifolium Nutt. is very similar also but has many more cauline leaves below the branching of the inflorescence and more spreading hairs on its stems.

Photographs taken in Umstead State Park, Raleigh, NC., 9-22-02, at Pilot Mountain State Park, NC., 10-20-02, and in Eminence, MO., 9-21-03.