- Annual forb, sometimes taprooted, occasionally emergent aquatic.
- Loosely ascending to erect, to 80 cm, sometimes from a spreading base, occasionally rooting at the lower nodes, glabrous or rarely somewhat roughened with sparse, stiff, ascending hairs.
Stem and leaf bases.
- Opposite, simple, sessile, often with bases fused around stem. Blades to 20 cm, oblong-lanceolate to oblanceolate, tapered at each end, sharply pointed, usually sharply toothed, glabrous.
- Solitary terminal heads or loose, open clusters.
- Radiate or rarely discoid, nodding in fruit. Involucre with the outer series of 5-9 bracts 6-30 mm long, spreading to more commonly reflexed, mostly leaflike, narrowly lanceolate or linear, the margins entire but usually minutely roughened, the outer surface glabrous or sparsely short-hairy toward the base; the inner series of 6-9 bracts 4-10 mm long, lanceolate to narrowly ovate or ovate, glabrous. Chaffy bracts narrowly oblong, straw-colored to yellowish-tinged at the tip.
- Sterile, 6-8 per head or rarely absent, the corolla usually showy, 10-15 mm long, yellow.
- Fertile, 40-100 per head, the corollas 3-4 mm long, yellow. Pappus of 4 awns mostly 2-4 mm long, these with downward-pointed barbs, erect at fruiting.
Ray and disk florets, chaff.
- Achenes 4-8 mm long, narrowly wedge-shaped, with persistent barbed pappus awns, flattened and somewhat 4-angled in cross-section, the angles pale and somewhat thickened or sometimes narrowly winged, the faces sometimes with several faint longitudinal lines, dark brown to purplish black, glabrous or with sparse, short, pustular-based hairs.
- Other members of the genus
, and more broadly, many other members of the
have similar flowering heads.
- This species can be found scattered throughout most of Missouri, possibly excepting the Glaciated Plains division. It occurs throughout most of the northern 2/3 of the U.S. and into Canada. It is easy to identify by its wet habitat, showy yellow flower heads, and opposite leaves fused around the plant stem. The specific epithet
means "nodding," but the heads only nod consistently when in fruit. Steyermark and others have named numerous infraspecific entities, but these appear to represent ecological variants and are not currently recognized in Missouri.
Photographs taken along the shores of the Current River, Shannon County, MO., 9-20-03 (DETenaglia); also at Onondaga Cave State Park, Crawford County, MO, 9-25-2014, and Glassberg Conservation Area, Jefferson County, MO, 10-5-2018 (SRTurner).
Jennifer Anderson. United States, IA, Scott Co., Davenport, Nahant Marsh. 2002.
Robert H. Mohlenbrock. USDA SCS. 1989.
Midwest wetland flora: Field office illustrated guide to plant species
. Midwest National Technical Center, Lincoln. Provided by USDA NRCS Wetland Science Institute (WSI).
nodding bur marigold
This plant can be weedy or invasive according to the authoritative sources noted below.This plant may be known by one or more common names in different places, and some are listed above. Click on an acronym to view each weed list, or click here for a composite list of
Weeds of the U.S.
Fernald & H. St. John;
(2—)20—100(—400+) cm (stems sometimes rooting at proximal nodes).
(rarely in 3s) sessile; blades lance-ovate or oblanceolate to lanceolate or linear, 40—100(—200+) × (2—)5—25(—45+) mm, bases cuneate to rounded, margins usually coarsely dentate to serrate, sometimes entire, sometimes ciliate, apices acute to acuminate, faces glabrous.
(erect or nodding at flowering, usually nodding in fruit) borne singly or in open, ± corymbiform arrays.
of (3—)5—8(—10) spreading to reflexed, oblong to lance-linear, often ± foliaceous bractlets or bracts (3—)8—12(—25+) mm, margins usually ciliate, abaxial faces usually glabrous, bases sometimes hispidulous.
± hemispheric or broader, (3—)6—10 × (8—)12—20+ mm.
6—8+, ovate or lance-ovate to lanceolate, 2—10 mm.
usually 6—8, sometimes 0; laminae orange-yellow, 2—15(—18) mm.
(10—)40—100(—150+); corollas orange-yellow, 3—4 mm.
blackish or brown, usually ± flattened, sometimes ± 4-angled, ± cuneate, outer (3—)5—6+ mm, inner 4—8 mm, margins (± thickened or winged) retrorsely ciliate, apices ± truncate to convex, faces ± striate, glabrous or tuberculo-strigillose;
of (2—)4, ± erect, retrorsely barbed awns (1—)2—4 mm.
= 24, 48.
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