Solidago radula Nutt.

Solidago radula plant

Family - Asteraceae

Stems - Multiple from base, from fleshy roots and a small caudex, erect to arching with age, pubescent, herbaceous but stout, simple, to 1m tall, terete, often striate. Mature stems ~4mm in diameter.

Solidago radula stem

Leaves - Basal leaves absent at anthesis. Cauline leaves alternate, sessile, shallow serrate, puberulent, very scabrous (especially lowest leaves), to +/-10cm long, +/-2cm broad, oblong but tapering to the base, acute at apex. Upper cauline leaves oblong-elliptic and reduced upward. Leaves with a single midrib and typically two obvious basal lateral veins. Serrations of leaves typically with a minute whitish tip.

Solidago radula leavesPressed leaves.

Inflorescence - Terminal pyramidal arrangement of axillary paniculate secund flower heads. Inflorescence essentially determinant. Individual paniculate clusters arching. Leaves reduced to bracts in inflorescence. Each peduncle subtended by 1 reduced bract. Bracts subulate and greenish. Flower heads secund on upper portion of axis yet originating from all around the axis. Peduncles pubescent.

Solidago radula inflorescenceInflorescence.

Involucre - To 5mm tall (long), 2mm in diameter, cylindric. Phyllaries imbricate, greenish at base and fading to yellow at the apex, linear, glabrous, the longest to +3mm long, 1mm broad. Apex of phyllaries rounded to subacute, fimbrillate.

Ray flowers - 5-6 per head, fertile, pistillate. Ligules yellow, 2mm long, 1mm broad, glabrous. Corolla tube 2.1mm long, sparse pubescent. Pappus of barbellate bristles to 2.5mm long. Achenes in flower .8mm long, pubescent. Styles bifurcate, yellow at the apex, glabrous. Stigmas spreading.

Disk flowers - 4-5 per flower head. Corolla 5-lobed, 3mm long, glabrous. Lobes acute, spreading, .8-.9mm long, glabrous. Stamens 5, adnate in the basal 1/3 of the corolla tube. Filaments greenish, glabrous, ~1mm long. Anthers yellow, 1.5mm long, exserted, connate around the style, acute at the apex. Style exserted beyond the anthers, bifurcate, glabrous, yellowish at the apex, yellowish-green below. Stigma converging. Achenes and pappus as in ray flowers.

Solidago radula flowers

Flowering - May - October.

Habitat - Glades, dry open rocky woods, ledges and bluff escarpments.

Origin - Native to U.S.

Other info. - This species can be identified in the field by its heavily scabrous serrate leaves which are typically numerous on the stem and fairly rigid. This plant does not acquire the large size of some of the other species in this genus. It practically always nods like in the plant picture above.
Steyermark breaks the species up into 3 varieties based on phyllary size and shape but these can be difficult to differentiate so I won't go into those here.

Photographs taken at the Current River Conservation Area, Reynolds County, MO., 7-24-01.


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