Solidago altissima L.

Tall Goldenrod

© SRTurner

Family - Asteraceae/Astereae

Habit - Rhizomatous perennial forb, often with thickened bases.

Stem - Strongly ascending to erect, 1 to several, to 2.5 m (usually longer than 1 m), with several fine, longitudinal lines or grooves, moderately to densely pubescent with short, curved hairs, sometimes less densely hairy toward the base, not shiny, not glaucous.

	Stem.
© SRTurner

Leaves - Chiefly cauline, the largest leaves in the lower 1/3-1/2 of the stem, the basal leaves usually absent at flowering. Basal and lowermost stem leaves with the blade 3-15 cm long, 0.5-2.5 cm wide, mostly 5-13 times as long as wide, narrowly oblanceolate to narrowly lanceolate, somewhat thickened and stiff, tapered gradually to a sessile or very short-petiolate base, tapered to a sharply pointed tip, the margins sharply toothed to nearly entire and usually roughened or minutely hairy, the upper surface moderately to densely pubescent with short, curved to spreading hairs or sparsely to moderately roughened with minute, bulbous-based hairs, the undersurface moderately to densely pubescent with short, spreading hairs (these also sometimes slightly bulbous-based), with 3 main veins, the lateral pair often originating well above the leaf base and finer than the midvein, the veinlets often difficult to observe, forming an irregular, dense network. Median and upper stem leaves 1-15 cm long, narrowly elliptic to narrowly lanceolate, sessile, the margins of the uppermost leaves often entire, otherwise similar to the lower stem leaves.

	Stem and leaves.
© SRTurner

	Leaf adaxial.
© SRTurner

	Leaf abaxial.
© SRTurner

	Abaxial surface.
© SRTurner

Inflorescence - Pyramidal panicles, the longer branches and often also the tip arched or nodding.

	Inflorescence.
© SRTurner

Heads - Numerous, oriented upward along inflorescence branches. Involucre 3.0-4.5 mm long, the bracts in 3-6 unequal series. Involucral bracts lanceolate, usually sharply pointed at the appressed- ascending tip, the margin sparsely hairy, the outer surface glabrous, usually entirely yellowish. Receptacle naked.

	Flowering heads.
© SRTurner

Florets - Ray florets 10-16, the corollas 3-4 mm long, yellow. Disc florets 3-7, the corollas 3.0-3.5 mm long, the lobes 0.5-0.9 mm long, yellow. Pappus 2.8-3.5 mm long, some of the bristles slightly thickened toward the tip.

	Florets.
© SRTurner

Fruits - Achenes 0.6-1.2 mm long, narrowly obovoid, finely hairy.

Flowering - August - November.

Habitat - Prairies, upland forests, streambanks, pastures, fields, roadsides, open disturbed areas.

Origin - Native to the U.S.

Lookalikes - Other goldenrods, particularly S. canadensis and S. gigantea.

Other info. - This is undoubtedly the most common and weediest of Missouri's goldenrods. It will grow in almost any sunny location, sometimes aggressively monopolizing fields. It is found throughout Missouri and across most of the continental U.S., except for the far western regions of the country.

Identification of goldenrods can be challenging. Important characters to note are the shape of the inflorescence and the distribution of leaves along the stem. Inflorescences can be pyramidal (as is the case here), spikelike, or flat-topped. Unfortunately, the shape of the inflorescence can become distorted or obscured, particularly in depauperate individuals. The leaf disposition can be either cauline, with the largest leaves near the central portion of the stem (the case here), or basal, in which the largest leaves are present at flowering and located near the base of the plant. Solidago altissima closely resembles S. gigantea in both of these respects. The leaf texture distinguishes between these two species, with S. altissima having leaves with rough surfaces and S. gigantea having smooth leaves.

Currently, two varieties of S. altissima are recognized in Missouri. These vary by the nature of the hairs on the leaf upper surfaces, with var. altissima having bulbous-based hairs, and var. gilvocanescnes having short, curved to spreading hairs.

A key for identifying Missouri goldenrods in their vegetative (non-flowering) state has been published by Justin Thomas in the journal of the Missouri Native Plant Society (Missouriensis, 2002, 23, 32-38).

Photographs taken near Labadie, Franklin County, MO, 9-15-2019 (SRTurner).