Comprehensive DescriptionRead full entry
DescriptionThis perennial plant is about 1½–3' tall and unbranched, except for the flowering stalks near the apex. Missouri Goldenrod produces both fertile (flowering) and sterile (non-flowering) shoots. The central stem is light green to dark red, terete (round in circumference), and glabrous; the lower portion of this stem may become slightly woody with age. Along the entire length of this stem, there are alternate leaves that become smaller as they ascend. These leaves are up to 5" long and ¾" across; they are more or less elliptic in shape and serrated along their middle to outer margins. Each leaf usually has 3 prominent veins (a central vein & 2 lateral veins); the lateral veins are parallel with the central vein along much of its length. However, on many upper leaves only the central vein is prominent. The tips of the leaves are acute, while their bases taper gradually into petioles. Most of these petioles are 3 mm. or less in length, although the lowest leaves have longer petioles that are partially winged. From the axils of the middle to upper leaves, short tufts of small secondary leaves may develop. The upper leaf surface is medium green and glabrous, while the lower leaf surface is light green and glabrous. A panicle of flowerheads up to 6" long and 4" across terminates the central stem of each fertile shoot. This panicle is pyramidal, obpyramidal, or rhomboid in outline; its branches are widely spreading to ascending and straight to somewhat recurved. These branches divide into short secondary branches and peduncles; the latter terminate in small flowerheads. The branches and peduncles are light green to nearly white and either glabrous or pubescent. Intermingled among these branches, there are small leafy bracts up to 1½" long and ¼" (6 mm.) across. Each flowerhead is about 3 mm. across and 5 mm. long; it consists of several disk florets that are surrounded by 6-12 ray florets. The tiny corollas of these florets are yellow to golden yellow; they are tubular in shape with 5 spreading to ascending lobes along their upper rims. The petaloid rays of the flowerheads are bright yellow, oblong in shape, and widely spreading. Surrounding the base of each flowerhead, there are phyllaries (floral bracts) in several overlapping series; they are about 2 mm. long, light green to light yellow, oblong in shape, glabrous, and appressed together. The blooming period usually occurs from mid-summer to late summer, lasting about 3 weeks for a colony of plants. Afterwards, the florets are replaced by achenes with small tufts of white hair at their apices. These achenes are about 2 mm. long and bullet-shaped; they are distributed by the wind. The root system is mostly fibrous and rhizomatous; an older plant may produce a small caudex. Missouri Goldenrod reproduces by clonal offsets from the rhizomes and by reseeding itself. It often forms colonies that contain both fertile and infertile shoots.