Rudbeckia missouriensis Engelm.

Rudbeckia missouriensis plant

Family - Asteraceae

Stems - To +/-60cm tall, from a stout rhizome and thick-fleshy roots, hirsute, scabrous (the hairs with swollen bases), multiple from the base, erect, branching at the apex, slightly angled or not.

Rudbeckia missouriensis stem

Leaves - 1st year leaves in a basal rosette. Leaves petiolate. Petioles very slightly winged, +/-5cm long. Blades linear-oblong to linear-spatulate, appearing entire but actually shallow serrate, with a single midrib and 2 prominent lateral veins arising near the base of the blade and becoming parallel with the midrib, pubescent as the stem, to 15cm long (with petiole), 1.4cm broad. Teeth of margins with a minute yellow or yellowish-green tip.

Rudbeckia missouriensis leavesPressed leaves.

Rudbeckia missouriensis basalsBasal rosette of first year growth.

Inflorescence - Single pedunculate flower head terminating each stem. The peduncle hollow below the receptacle.

Involucre - Basically flat to cupulate, -2.5cm broad. Phyllaries imbricate, in 2-3 series, lanceolate, to +1cm long, 4mm broad, spreading, sparse pubescent internally, pubescent as the stem externally.

Rudbeckia missouriensis involucreInvolucre.

Ray flowers - 10-13 per flower head, sterile. Ligules yellow, pubescent abaxially, glabrous adaxially, with a shallow notch at the apex, to 2.3cm long, 6-7mm broad. Achene (in flower) white, 3-sided, glabrous, 1.5mm long. Pappus absent.

Disk flowers - Disk to 1.5cm broad. Corollas glabrous 4-5mm long, white at the base, deep purplish brown above, 5-lobed. Lobes acute, to 1mm long, erect to spreading. Stamens 5, mostly included, adnate near the base of the corolla tube. Filaments compressed, 1.2mm long, translucent, with an obvious midvein. Anthers deep purplish-brown, -2mm long, connate at the base, surrounding the style. Style glabrous, slightly exserted, white basally, deep purplish brown at the apex, bifurcate. Achene (in flower) 4-sided, white, glabrous, 2mm long. Pappus absent. Receptacle conic. Chaff partially enclosing the disk flowers, to +5mm long, translucent but with purple margins near the apex, acute, glabrous or with a few hairs externally.

Rudbeckia missouriensis flowers

Flowering - June - October.

Habitat - Glades, barrens, bald knobs, rocky prairies.

Origin - Native to U.S.

Other info. - This is a characteristic Missouri Ozark species. It is quite common in the habitats mentioned above and is therefore easy to identify in the field because of its habitat. Hundreds of plants can be found in an undisturbed area. This species grows on limestone substrata.

Photographs taken off Hwy 106, Shannon County, MO., 8-10-03.


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