Rudbeckia subtomentosa Pursh

Rudbeckia subtomentosa plant

Family - Asteraceae

Stems - To +1.2m tall, from thick rhizomes, carinate, tomentose, branching above, herbaceous, erect.

Leaves - Alternate, petiolate, 3-lobed (simple in upper-most portion of plant), subtomentose below, scabrous above. Lateral lobes smaller than terminal lobe, serrate, acute to acuminate. Terminal lobe serrate, lance-ovate, acuminate. Leaves thick and firm. Petioles subtomentose.

Rudbeckia subtomentosa leaves

Inflorescence - Loose cymose arrangement of terminal flower heads. Peduncles tomentose. Each division of inflorescence subtended by foliaceous bract.

Involucre - Phyllaries tomentose, spreading, linear-subulate, in several series, to +/-1.2cm long, -3mm broad.

Rudbeckia subtomentosa involucreInvolucre.

Ray flowers - Sterile. Ligule yellow, to 3.5cm long, 6-7mm broad, pubescent below, glabrous above. Achenes 3-angled, 1.2mm long. Pappus absent or a minute crown.

Disk flowers - Disk to 1.6cm in diameter. Corolla tube 2mm long, 5-lobed, glabrous, purplish-brown. Lobes acute, recurved to spreading. Stamens 5, adnate at base of corolla tube. Anthers connate around style, purplish-brown, 1.3mm long, slightly exserted from corolla. Style bifurcate, deep purple. Achene 2.2mm long (in flower), white, glabrous, 4-angled. Pappus absent or a minute crown. Receptacle conic. Chaff to 5mm long, purplish, pubescent at apex.

Rudbeckia subtomentosa flower

Flowering - July - October.

Habitat - Prairies, low meadows, open slopes, streambanks, roadsides.

Origin - Native to U.S.

Other info. - This is a common plant throughout most of Missouri.The flowers are easily recognized as are the thick, rough, 3-lobed leaves.
Two forms of R. subtomentosa exist in Missouri. The form pictured above is form subtomentosa, which has purplish-brown disk flowers. Form craigii (Sherff) Fern. has yellow disk flowers and is rare.
This is NOT the plant typically called "Black-eyed Susan", that plant is the similar R. hirta L.

Photographs taken at the Dorris Creek Prairie Conservation Area, Barton County, MO., 7-28-00.


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