Stiff-haired Sunflower is a native erect perennial forb growing on stems from 2 to 6-1/2 feet high. Stems have stiff short hairs and are frequently a deep reddish color.
The leaves are mostly all opposite leaves with short stalks, 0.4 - 2 cm long. Blades are 6.5-18 cm long x 1-8 cm wide. They are rough above and hairy under with dotted glands. Leaf shape is lanceolate to ovate. Bases are truncate to broadly rounded, with 3 main veins rising from the base. Margins of the larger leaves have some coarse serrate teeth.
The floral array is a few flower heads on thick stalks, 1 to 5 cm long, and not numerous (1 to 7), atop the stem.
Flower: Flowers are of two types, ray florets and disc florets. The central disc has 40+ disc florets with yellow corolla tubes with 5 pointed lobes at the opening. These are bisexual fertile flowers with 5 stamens that have yellow to dark brown or black anther appendages which surround a single style. (yellow is said to be more common). These flowers are surrounded by 10 to 15 ray florets with yellow corollas and yellow rays which are 15 to 20 mm long. These are not fertile. The entire flower is 1-3/4 to 3-1/2 inches wide. The flower head is enclosed by a series of green phyllaries (bracts) that number 18 to 25 and are usually loose and spreading but not reflexed, lanceolate in shape and the margins usually have fine hair if not the entire outer surface but no gland-dotting on the outer surface.
Seed: Fertile flowers produce a dry cypsela, 4 to 4.5 mm long, that has two small awns. Seeds are dispersed by dropping or by the wind. Like most seeds of Helianthus these require at least 30 days of cold stratification for germination.
Habitat: Stiff-haired Sunflower grows in open woods, roadsides and meadows where the soil is drier and there is full sun. The root system is rhizomatous.
Names: The genus Helianthus is from two Greek words, helios for 'sun' and anthos for 'flower'. The species hirsutus means "hairy." The author name for the plant classification, ‘Raf.’ is for Constantine Samuel Rafinesque, (1783-1840), European polymath who traveled in the United States, lived here many years, collected specimens, and published over 6,700 binomial names for plants. He applied to be botanist on the Lewis & Clark expedition but Jefferson turned him down in favor of training Lewis to act as botanist and saving the expense of another person.
Comparisons: This species is quite variable in leaf shape and amount of leaf hair. It also can hybridize with other sunflowers such as H. strumosus, Paleleaf Woodland Sunflower and H. tuberosus, Jerusalem Artichoke, making visual identification difficult. H. strumosus has smooth stems, H. tuberosus has phyllaries that have dark green to almost black coloration. Another confusing species is Woodland Sunflower, H. divaricatus (not present in Minnesota) where the stems are also usually smooth and the leaves are without stalks.
The species of Helianthus currently in the Garden are: H. hirsutus, Stiff-haired Sunflower; H. pauciflorus ssp. pauciflorus, Stiff Sunflower; H. tuberosus, Jerusalem Artichoke, and Helianthus giganteus, Giant Sunflower.
Above: Stiff-haired Sunflower is a tall plant with 1 to 7 flower heads. Most leaves are opposite. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: 1st photo - The floral array is one to a few stalked flowers at the top of the stem. 2nd photo - Stems may be green but are frequently a deep reddish purple and with short stiff hairs.
Below: 1st photo - The disc florets number 40+, have corollas with yellow pointed lobes. Stamens can have dark appendages and they surround the central style. These open first from the outer edge. 2nd photo - The flower head has long pointed phyllaries that are spreading and hairy, at least on the margins.
Below: The stem leaves have pointed tips and rounded to truncate bases. Margins with coarse serrate teeth.
Below: The underside can be paler in color with fine hair and usually is gland dotted.
Notes: Eloise Butler had catalogued Stiff-haired Sunflower in her plant index of Sept 6, 1907 as present in the Garden area. She listed it as H. divaricatus, but that species is not found in Minnesota so it is likely it was H. hirsutus or H. strumosus. She did record planting H. hirsutus numerous times, beginning on Aug. 15, 1916 when she brought in 3 plants from Glenwood Park (which partially surrounded the Garden and is now named Theodore Wirth Park). She planted more in 1921, '26, and '32. H. hirsutus was listed on Martha Crone's 1951 inventory of plants in the Garden at that time. Stiff-haired Sunflower is native to Minnesota, mostly in counties in the Eastern half of the State including most of the Metro area and excepting the Arrowhead region. This plant is very similar in appearance to H. strumosus, the Pale-leaved Sunflower but is more widely distributed in the State than H. strumosus. There are a total of 12 species of Helianthus native to Minnesota.
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"