rough oxeye

Rough oxeye, also called false sunflower, is a 2′ to 5′ tall, erect, perennial forb that rises from a creeping rhizome with fibrous roots. There are three varieties of this plant. The center of distribution for this variety is the upper Great Plains. It is the only variety found in Minnesota.

The stem is erect, occasionally branched, even bushy on open situations. The upper part of the stem is rough to the touch due to minute, stiff hairs. The lower stem is less rough.

Leaves are opposite, both on the main stem and within the inflorescence. They are triangular egg-shaped, roughly like an equilateral triangle. They are on leaf stalks that can be 1 ⁄16″ to ⅝″ long, those of the main leaves averaging ½″. The blades can be 2⅓″ to 4¾″ long and ¾″ to 2″ wide and taper gradually to a pointed tip. The main leaves are usually 2¾″ to 4″ long and 1″ to 19 ⁄16″ wide. They are conspicuously veined. The upperside is rough to the touch due to minute, stiff hairs. The underside is less rough. The margins are coarsely toothed.

The inflorescence is 1 to 15 erect flower heads on 3½″ to 10″ long, leafless stalks at the ends of the stems.

The flower head is 2″ to 3½″ wide and has 8 to 18, usually 12 to 15, yellow ray florets. The disk is cone-shaped, ⅓″ to 1″ wide, and has 10 to 75 slightly darker yellow disk florets. There is no floral scent.

Unlike true sunflowers in the family Helianthus, the ray flowers are fertile. They remain attached to the head after they shrivel and become papery (see photo below).

2′ to 5′

Yellow ray florets, slightly darker yellow disk florets

Dry. Fields, prairies, woods, waste places. Full sun.

July to September

Sources

2, 3, 4, 5, 7, 28, 29, 30.

Native

Common

The species Heliopsis helianthoides has two, three, or four children (subtaxa), depending on the source. USDA PLANTS recognizes four varieties. GRIN, ITIS, Flora of North America, and Plants of the World Online recognize two varieties. iNaturalist lists three varieties. NCBI recognizes one variety, one subspecies, and one variety of that subspecies. World Flora Online recognizes two subspecies and one variety of one of the subspecies.

False sunflower has two or four subspecies, depending on the source. Flora of North America recognizes only two. The eastern variety is var. helianthoides. The leaf underside is hairless (smooth) or sparsely covered with minute, short, stiff hairs (glabrous or minutely scabrellous). The western variety is var. scabra. The leaf underside is moderately to densely covered with minute, short, stiff hairs (moderately to densely scabrellous).

The western variety Heliopsis helianthoides var. scabra is sometimes called “smooth oxeye,” but this is a misnomer. It suggests that the leaves are smooth, not scabrellous. A very few sources, including iNaturalist, use the more appropriate name “rough oxeye.”

Plant

Plant

Plant

Flower head

Flower head

Flower head

Shriveled ray florets still attached

Cone-shaped disk

Cone-shaped disk

Cone-shaped disk

Involucre

Involucre

Leaves

Leaves

Stem

Stem

Heliopsis helianthoides smooth oxeye
Frank Mayfield

Oxeye Sunflower - Heliopsis helianthoides in bloom at Ion Exchange
Ionxchange

Greg Watson
5/27/2022

Location: Root River State Trail - Lanesboro to Whalan

Smooth Oxeye flowers along the trail.

Location: Pennington Co. MN

Here is a Smooth Oxeye or False Sunflower head. This wildflower just started showing up in ditch rightaway around my property.