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Helianthus Strumosus

Helianthus Strumosus

Helianthus Strumosus

Woodland Sunflower is a rather variable species, particularly in leaf shape and degree of hairiness. The few things all the references seem to agree on, and that can actually help distinguish this from other Minnesota native sunflowers, are: a mostly smooth stem that may have a whitish bloom, leaf stalks usually at least ½ inch long, and bracts that do not much exceed the width of the flower disk. Woodland Sunflower most closely resembles Hairy Sunflower (Helianthus hirsutus), which has a bristly hairy stem all the way to the base of the plant, and leaf stalks less than ½ inch long. Woodland Sunflower hybridizes with both Hairy Sunflower and Jerusalem Artichoke (Helianthus tuberosus), which makes an ID even more challenging.Helianthus strumosus (Woodland Sunflower) is a showy perennial with narrow, oval leaves, white underneath, and a profusion of yellow flowers, 2-4 in. across (5-10 cm), each adorn with up to 8-20 yellow rays and a yellow center disk. They are held in loose clusters of 3-15 blossoms at the branch tips, and are borne on stout, erect, smooth stems. Blooming from mid summer to fall, they are particularly attractive to birds as they love to eat the seeds directly from the seedheads. Perfect for adding late season color in partly shaded borders and naturalized areas. Helianthus strumosus, known by the common name pale-leaf woodland sunflower or just woodland sunflower (a general name also used for several other native species of sunflowers), of the Aster (Asteraceae) family, is a deciduous rhizomatous perennial which occurs throughout the eastern U.S. from eastern Texas and North Dakota to the Atlantic and Gulf Coasts. In Arkansas, it is reported from across much of the state and possibly occurs statewide. The genus name is based on Greek words for “sun” and “flower”. The specific epithet relates to having strumae (cushion-like swellings) at the base of hairs on the upper stems. This plant is usually found in full to partial sun in dry to mesic soils of open woods, glades, prairies, roadsides and river banks

Several characteristics help distinguish Helianthus strumosus from two other widespread and very similar native woodland sunflowers, namely, Helianthus divaricatus and Helianthus hirsutus. Helianthus strumosus has: 1) stems that are typically rough, but not especially hairy, 2) leaf petioles that are ¼ inch or more long with leaf blade extending onto petioles, 3) two primary lateral veins near the leaf base that originate at a point well within leaf blade, and 4) phyllaries that are about twice as long as their widths. Nevertheless, it should be admitted that even the experts often have difficulty distinguishing among these 3 species of woodland sunflower. And without the roots, even Jerusalem artichoke, Helianthus tuberosus, becomes tough to tell apart from them. Paleleaf Woodland Sunflower is very similar in appearance to H. hirsutus, the Stiff-haired Sunflower, with which it hybridizes, but is less widely distributed. There is some difference and confusion in the common names applied to this plant. Some sources such as the Minnesota DNR List of Native Plants don't refer to it as "Pale-leaved" but call it the Woodland Sunflower which conflicts with an alternate name for H. divaricatus. The U of M Herbarium calls it "Paleleaf Woodland Sunflower," which is the name we use here, whereas Flora of North America prefers "Rough-leaved Sunflower," - another reason to use scientific names. There are a total of 12 species of Helianthus native to Minnesota. (Source: www.friendsofthewildflowergarden.org)

 

 

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