Smooth Oxeye is a native erect perennial forb forming an flowering stem from creeping rhizomes. Stems grow 4 to 6 feet high and vary with the amount of stiff hair thereon from none to much. There are shallow stem ridges and there can be a purplish color tinge at the nodes or throughout the lower stem section. A moderate amount of branching occurs near the top. In the Upland Garden this plant is one of the earliest yellow sunflower types to bloom, along with Black-eyed Susan - both have a long flowering period.
The leaves are opposite, with at least a one inch stalk and with sharp coarse teeth on the leaf margins. The shape is deltate to narrowly ovate, pointed tip and the truncate base abruptly tapers to the stalk. The leaf surface of this variety is rough from short stiff hairs. The underside paler in color. Size varies from 6 - 12 cm long x 2 - 5 cm wide.
The floral array is one to 15 flower heads each borne singly on a long (9 - 25 cm) leafless stalk for the top area of the stem.
The open flower head is up to 3 1/2 inches wide and is composed of two type of florets, both fertile. The yellow ray florets number 10 to 18, are pistillate only and being fertile are unlike true sunflowers where the ray florets are sterile, hence the alternate common name of "False Sunflower". Rays are 2 - 4 cm long. The central disc is composed of 10 to 75+ bisexual disc florets, with yellowish-brown tubular corollas with five pointed lobes at the throat that are of a brighter shade of color and are longer than the floret tube. The lobes are spreading when the floret opens. The five stamens have dark brown anthers and tightly surround the the single style which is bifurcated at the tip. The phyllaries around the outside of the flowerhead are in 2 series, sometimes 3, ovate to oblong, with the outer series longer, the inner broader, and all (along with the flower stem) either lacking hair or with fine hair - usually found with hair.
Seed: Both types of flowers produce a dry elongated brown, ribbed cypsela without attached pappus; ray floret cypselae are about 4 to 5 mm in length, the disc floret cypselae are of smaller size. Seeds require at least 30 days of cold stratification for germination.
Habitat: Smooth Oxeye prefers loamy soil but tolerates other types. Moist to dry mesic moisture and full sun or at least 5 to 6 hours per day. It grows from a creeping rhizomatous root system and can be aggressive in spreading. It can be grown from seed or root divisions.
Names: Both genus and species mean the same thing. The genus name, Heliopsis, is from two Greek words - helios, meaning 'sun' and opsis, meaning 'likeness' (like a sunflower). The species name, helianthoides, is also from the Greek meaning 'like Helianthus' or like the sunflower.
The author names for the plant classification are: First to classify, in 1753 assigning the name Buphthalmum helianthoides was - 'L.', which refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. His work was amended in 1826 by ‘Sweet’ which refers to Robert Sweet (1783-1835) English botanist, fellow of the Linnean Society and author of a number important works including Sweet’s Hortus Britannicus.
Comparisons: While the flower may resemble other sunflowers, it is distinguished by its early and long bloom period, the fertile ray florets and the broader leaves. See notes below on distinguishing between the two recognized varieties of the species. Compare Black-eyed Susan.
Above: The flower head has 10 to 18 perimeter fertile ray florets and 75+ fertile central disc florets. The disc florets (2nd photo) have yellow tube corollas with 5 lobes that form spreading points when open, dark brown anthers and a yellow bifurcated style. Florets open from the edge toward the center.
Below: 1st photo - The flower heads are on tall leafless stalks. 2nd photo - The phyllaries of the head are in 2 to 3 series, the inner series progressively smaller. In var. scraba, the stalk, head and phyllaries usually will have fine hair.
Below: The opposite leaves of var. scraba have a one inch+ long stalk and are deltate in shape with coarse marginal teeth.
Below: 1st photo - The leaf upper surface and margins of the teeth have stiff short hair while the underside (2nd photo) is of paler color with many short whitish hair and longer hair on the ribs and veins.
Below: 1st photo - The flower tends to be single on a tall leafless stalk. 2nd & 3rd photos - Stems have shallow ridges and can be smooth to having fine hair as this example shows. A purplish color tinge can be present at the leaf nodes and sometimes on the entire lower stem.
Notes: Smooth Oxeye is indigenous to the Garden area, Eloise Butler had catalogued this plant in her plant index as present. She listed it as H. scraba, which is not now considered a variety of H. helianthoides. Martha Crone also listed H. scraba in her 1951 inventory of Garden plants. Cary George reported planting it in 1995. H. scraba is now officially listed by botanists as Heliopsis helianthoides (L.) Sweet var. scabra, and is the variety native to Minnesota and the only species of Heliopsis found in the state.
It is found in most counties throughout Minnesota except a few in the Northern part of the State. There is another variety found in North America, but not in Minnesota, Heliopsis helianthoides (L.) Sweet var. helianthoides. The difference is in the leaves. Var. scraba has leaves deltate to narrowly ovate in shape with rough hairy faces. Var. helianthoides has leaves ovate in shape with minor roughness or none at all. Intermediates are known to exist.
Eloise Butler wrote in July 1911: "The meadows and copses are now wild with the ox-eye, much like the wild sunflowers, and distinguished from them only by the specialist in a few details. The ox-eye is a forerunner of the golden seas of bloom that characterize the waning summer. It is to be commended for its profuse growth and for its adaptability to varying conditions." Published in the Minneapolis Sunday Tribune July 9, 1911
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"