Agoseris cuspidata (Pursh) Raf.

Agoseris cuspidata plant

Family - Asteraceae

Stems - Plant acaulescent. Leaves and flowering stems from a big vertical taproot, with milky sap. Taproot woody.

Leaves - Leaves in a basal rosette, sessile, linear-attenuate, white at the partially sheathing base, mainly dark green with an adaxial white strip along the midrib, to 20cm long, 1.5cm broad at the base, typically folded. Margins entire, often sinuous, fringed with dense white hairs. Abaxial surface of the leaf with long whitish pubescence on the veins. Adaxial surface with lanate-tomentose pubescence on the midvein. The hairs of the plant multicellular.

Agoseris cuspidata leaves

Agoseris cuspidata leaf marginsView of the leaf margins.

Inflorescence - Single flower head terminating the flowering scape, typically one per plant. Scape (peduncle) to +/-15cm tall, lanate-tomentose, fistulose, carinate, appearing gray because of the pubescence.

Agoseris cuspidata scapeClose-up of the flowering scape.

Involucre - Phyllaries imbricate or overlapping but subequal in length, spreading at the apices, to -2cm long, 5-6mm broad, lanceolate, acuminate, light green with a brown mid-portion, glabrous. Inner phyllaries slightly smaller than the outer.

Agoseris cuspidata involucreInvlocure.

Ray flowers - Flower head to 5cm broad. Flowers many per head. Corolla tube whitish, densely antrorse pubescent externally, 1cm long. Ligule yellow adaxially, with a brown mid-stripe abaxially, 4-5-notched at the apex (the teeth to .75mm long), pubescent abaxially, glabrous adaxially, to 2cm long, 5mm broad. Stamens 5, adnate near the apex of the corolla tube. Filaments translucent-yellow, 2mm long, glabrous. Anthers orange, exserted, to +5mm long, connate around the style. Style yellow, antrorse pubescent, bifurcate at the apex for 1-2mm (the ends spreading). Achenes (in flower) green, glabrous, ribbed, 1.5mm long, cylindric. Pappus of white capillary bristles to +1cm long. The bristles antrorse barbellate. Receptacle flat.

Agoseris cuspidata flowers

Disk flowers - Absent.

Flowering - April - June.

Habitat - Glades and rocky prairies.

Origin - Native to U.S.

Other info. - This is one of the most uncommon plants in Missouri only being found in 4 counties thus far. It is locally abundant in some areas, however. The plant is easy to identify in the field because of its habitat, dandelion-like flower heads, and grayish hairy leaves and scapes. The big taproot helps the plant to survive in its harsh glade habitat.

Photographs taken at Danville Conservation Area, Montgomery County, MO., 4-17-04.


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