Orange Coneflower is an erect perennial forb growing 2 to 4 feet tall, which places it in the shorter end of the Rudbeckia spectrum. Stems are ridged, green and either smooth surfaced or with moderate amounts of spreading hairs. Stems are multiple from the root crown.
The leaves are broadly ovate to elliptic with five main veins and a networked pattern between the main veins. Large leaves can have a ruffled, quilt-like look. Leaf surfaces can be smooth or have short hairs. The underside in particular, is paler in color due to fine whitish hair with some longer hair on the veins and surfaces. Lower basal leaves are stalked, with wings, and emerge from the root crown while upper stem leaves are stalkless. Lower leaves tend to have coarse teeth, uppers may be entire. Leaves taper to a point, bases vary from tapering to heart-shaped. [Note: There are significant differences in the leaves of some varieties of this species, i.e., some have upper leaves with coarse teeth].
The floral array varies from one composite flower per stem (most common) to a stalked array of 2 to 7 (very uncommon). The heads are held above the leaves on long stems.
The flowers have a central hemispherical disc, composed of 50 to 500+ bisexual and fertile disc florets that have corolla tubes that are yellowish-green in the lower half and dark brownish-purple in the upper half. The tubes have triangular lobes at the tip. The 5 stamens surround the central single style which is branched at the tip. The central disc is surrounded by 10 to 15 ray florets, neuter as to sex. These have orange-yellow rays are elliptic to narrowly elliptic is shape, that may reflex a bit near the tips but are seldom drooping. Around the outside of the flower head are 1 to 2 series of green phyllaries (floral bracts) that are usually hairy and quite long and broad - up to 2 cm long, narrowly elliptic in shape, tapering to a point. They reflex when the flower is fully open. (Some varieties differ in certain characteristics of the phyllaries.)
Seed: Fertile Rudbeckia flowers produce a dry 4-angled blackish cypsela, somewhat crown shaped, 2.2–4 mm long, that does not have any fluffy pappus. Most have a slight bend lengthwise. Dispersion is by scattering from the dry seed head. Seeds require 60 days of cold stratification for germination.
Varieties: There are seven recognized varieties of the species, mostly differentiated by variations in leaf and ray florets. Flora of North America (Ref.#W-7) has a good key. Plants shown here most closely resemble var. umbrosa.
Habitat: Orange Coneflower grows from a rhizomatous root system that can produce stolons in certain varieties and can then produce offsetting plants, but that is highly variable. Plants without stolons will enlarge the base clump of a plant from year to year; an overwintering rosette is present is some of the varieties. The erect stems and seed heads will persist into winter but be sure to trim them in early spring to make way for new growth. Flowering stalks shoot up only in early summer when the plant is ready to bloom. It grows best in full sun in wet-mesic to dry-mesic fertile well drained soils. In hot temperatures without rain, additional moisture helps. Divide clumps in early spring before growth starts. Leave room when planting - base clumps can get quite large.
Names: The genus Rudbeckia, is named after the Swedish father and son, - O. J. and O. O. Rudbeck, who were professors of botany and predecessors of Linnaeus. The species name, fulgida, means 'shining or glistening' and may refer to the ray petals, but that is not clear. The author name for the plant classification, ‘Aiton’ is for William Aiton (1731-1793), Scottish botanist, who succeeded Phillip Miller as superintendent of the Chelsea Physic Garden and then became director of Kew Gardens, where he published Hortus Kewensis, the Garden’s catalogue of plants.
Comparisons: Three others of the Rudbeckia genus must be mentioned: Black-eyed Susan, R. hirta, Sweet Black-eyed Susan, R. subtomentosa, and Thin-leaved Coneflower, R. triloba. R. hirta is also short, but has only a single flower stem that is very hairy, the leaves are more linear. R. triloba is a tall plant (to 6 feet) height, and the stem-leaves are lobed and the flower heads have fewer ray florets that are broader with more rounded tips. R. subtomentosa is also a taller plant (to 6 feet) whose basal leaves are lobed and the central disc is more flattened on top.
Above: The floral array varies from one composite flower per stem to several. One being the most common as seen here. Drawing of var. umbrosa 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: The flower head has a central hemispherical disc, with disc florets whose corollas are yellowish-green in the lower half and dark brownish-purple in the upper half. 11 to 15 ray florets surround the disc.
Below: 1st photo - Flower heads have 1 to 2 series of phyllaries (floral bracts) that are usually hairy and quite long and broad - they reflex when the flower is fully open. 2nd photo - The root is rhizomatous which forms an enlarging clump form year to year (see last photo below) and may form offsets.
Below: 1st photo - Stem leaves are usually stalkless, without teeth and with short rough surface hairs - the stem may have fine whitish hairs. 2nd photo - Basal leaves are stalked, with coarse teeth, five main veins.
Below: 1st photo - The upper part of the corolla of disc florets is dark brown. These open first from the outer edge. 2nd photo - The leaf underside has some spreading whitish longer hair and dense short white hair giving it a pale color. 3rd photo - The ridged stem can have spreading whitish hair as seen here. Note the wing on the leaf stalk.
Below: 1st photo - Orange Coneflower begins growth in late spring with a group of very small leaves. The plant remains small until early summer with a growth spurt occurs prior to the flower stalks forming. 2nd photo - The blackish cypselae, sharply angled, somewhat conical in shape with the larger end more crown shaped.
Notes: Orange Coneflower is not native to Minnesota but is found in neighboring Wisconsin. In North America it is found in most of the eastern half of the U.S. with the western extremity of the range being from Wisconsin south to Illinois then over to Missouri, Oklahoma and Texas. Excluded from this area is Louisiana, Vermont, New Hampshire and Maine. In Canada it is known in Ontario and Quebec.
Campbell and Seymour have proposed separating several new species out of the existing R. fulgida complex and have proposed a new outline for the complex. Their abstract (pdf)
Monet grew R. fulgida in his large garden at Giverny. (Ref. 36A)
Four species of Rudbeckia are considered native to Minnesota: R. laciniata, Green-headed (or Tall) Coneflower; R. hirta, Black-eyed Susan; R. triloba, Three-leaved (or Thin-leaved) Coneflower; and R. subtomentosa, Sweet Coneflower, although the latter is considered either an introduction or an extension of its normal range from Iowa and southern Wisconsin, as there is only one known population in the wild, in Mower County. The nursery trade has produced cultivars of Green-headed Coneflower, known commercially as Golden-glow, which have doubled ray florets and which occasionally escapes from cultivation.
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"