Rudbeckia hirta | SeedImages

Species category

Flower

Common name

blackeyed Susan

Diagnostic characters

Planting unit

AcheneAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.

Shape

Rectangular

Size

Length 2–2.8 mm
Width 0.5–1 mm
Thickness 0.5–1 mm

Color

Black

Texture

Minute reticulum between ridges

Other structures

Many longitudinal ridges and an apicalApical:
The distal end of the fruit or seed away from the point of attachment or attachment scar.
collar

Identification notes

AchenesAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.
elongated, narrow, slightly tapered from truncate apexApical:
The distal end of the fruit or seed away from the point of attachment or attachment scar.
to bluntly. Rounded base. Cross section is strongly four-sided with sharp angular corners. Color is black with shiny covering. Scar is basalBasal:
The base of the fruit or seed opposite the apical end.
.

Noxious weed seed categories

Not listed

AOSA examination list

Not included

Nomenclature

Family

Asteraceae

Valid name

Rudbeckia hirta L.

Rudbeckia hirta. Black achenes with a rounded base.	Rudbeckia hirta. Strongly four-sided achenes with a basal scar.
Rudbeckia hirta. Achenes with many longitudinal ridges and an apical collar.