Solidago ptarmicoides

Native

Dry. Prairies. Full sun. Sandy, limey soil, cracks in rocks.

July to September

White ray florets, white disk florets

4″ to 24″

This is a 4″ to 24″ tall, erect, perennial forb that rises on 1 to 20 or more stems from a thick, short, branched caudex. It looks much like an aster, little like a goldenrod.

The stem is erect, slender, and round. It is light green, not shiny, often with dark green vertical lines. It is unbranched below the middle and often branched above the middle. Near the top it is moderately rough to the touch due to a sparse covering of stiff, upward curved hairs. It is hairless or nearly hairless near the base.

One to several flowering stems rise from a rosette of basal leaves. Basal leaves are narrowly inversely egg-shaped to nearly linear, 2⅜″ to 4″ long, and ¼″ to ⅜″ wide. They are relatively thick, stiff, and stalkless or on short leaf stalks. They taper to the base and are angled to a sharp point at the tip. The upper and lower surfaces are hairless and smooth or sparsely hairy and slightly rough to the touch. There are usually 3 main veins visible on the underside. The margins are untoothed or have a few shallow, sharp, forward pointing teeth. There is often a second rosette of basal leaves adjacent to the flowering stem.

Lower stem leaves are alternate and similar to basal leaves. Basal and lower stem leaves are present at flowering time. Middle and upper stem leaves are alternate, linear or very narrowly inversely lance-shaped, ¾″ to 1½″ long, and ⅛″ to 3 ⁄16″ wide. They are stalkless and untoothed, They have a single main vein and may have a faint pair of lateral veins. They are otherwise similar to lower stem leaves.

The inflorescence is a branched, flat-topped or shallowly rounded, cluster (corymb) of flower heads at the end of the branches. The corymbs have short to long, ascending branches with 1 or a cluster of 2 or more uncrowded flower heads per branch. The flower heads are clustered at the end of the corymb branch. Each flower head is on a 1⅛″ to 1½″ long stalk.

The flower heads are about ½″ in diameter. The whorl of smaller bracts subtending the flower head (involucre) is 3 ⁄16″ to ¼″ long. The bracts of the involucre are linear to lance-shaped, tightly appressed, and hairless.

The flower heads have 10 to 25 usually white, sometimes pale cream-colored, ray florets and 30 to 36 usually white, sometimes pale cream-colored, disk florets. The ray florets are ¼″ to ⅜″ long. Each disk floret has 5 stamens with yellow anthers, which often causes the disk to appear yellow.

The fruit is a ribbed achene with a tuft of white hairs at the tip.

The white disk florets distinguish this plant from asters. The large white ray florets distinguish it from other goldenrods.

Taxonomy
This species was formerly classified as an aster and given the name Aster ptarmicoides. It was subsequently found to hybridize with Solidago species but not with Aster species, and is now classified as a goldenrod.