Senecio obovatus Muhl. - Roundleaf Ragwort

Senecio obovatus plant

Family - Asteraceae

Stems - To 50cm tall, from fibrous roots, erect, herbaceous, with leafy offshoots, hollow, carinate, typically simple.

Leaves - Alternate. Basal leaves long-petiolate, purplish below. Petioles to +7cm long, winged from decurrent leaf tissue, typically glabrous but with some arachnoid pubescence at the base. Blade orbicular, serrate, 4cm in diameter, tapering the base to the winged petiole, glabrous. Cauline leaves sessile, pinnatifid, glabrous but with arachnoid pubescence at the base, silvery green below, dull green above, reduced to bracts in the apical portions of the stem. Divisions of the leaf cleft.

Senecio obovatus leaves

Inflorescence - Terminal and axillary corymbose arrangement of flower heads. Peduncles carinate, with axillary tufts of arachnoid pubescence and with arachnoid pubescence just below the involucre.

Involucre - Cylindrical, 5mm tall (long), 4-5mm in diameter. Phyllaries uniseriate, linear, 4mm long, 1mm broad, reddish at the apices, arachnoid pubescent externally, glabrous internally.

Senecio obovatus involucresInvolucres.

Ray flowers - Flowers pistillate, fertile. Ligules yellow, to +1cm long, 2.5-3mm broad, glabrous, with 2 teeth at apex, oblong-linear. Styles yellow. Pappus of white capillary bristles to 5mm long. Achene glabrous.

Disk flowers - Corolla white at the base, expanded and yellow at the apex, 5-lobed, glabrous, 5mm long. Lobes acute, spreading to recurved, .6-.7mm long. Stamens 5, adnate in the upper half of the corolla tube. Anthers connate around the style, 1.9mm long. Style bifurcate, yellow at the apex, included or slightly exserted. Pappus of capillary bristles. Bristles to 5mm long, white, uniseriate. Receptacle flat.

Senecio obovatus flowers

Flowering - April - June.

Habitat - Rich and rocky woods, slopes, base of bluffs, borders of glades.

Origin - Native to U.S.

Other info. - This common woodland species can be found in many areas of Missouri but seems to be absent from the extreme northwest and southeast corners of the state. The showy flower clusters are easy to spot against the floor of the woods.
This species grows well from seed and would make a good shade garden specimen.
A few of the plants in this genus look very much alike and it can take some practice to ID them in the field correctly.
A modern synonym is Packera obovata (Muhl. ex. Willd.) W.A. Weber & A. Love

Photographs taken at the Noblett Lake Recreational Area, Douglas County, MO., 4-15-01.


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