Isopyrum biternatum (Raf.) T. & G. - False Rue Anemone

Isopyrum biternatum plant

Family - Ranunculaceae

Stems - To +30cm tall, herbaceous, glabrous, purplish-red, erect, from a small caudex and fibrous roots.

Leaves - Alternate, petiolate, stipulate, ternately divided. Petioles of the basal leaves to +/-12cm long, glabrous. Petiolules glabrous. Petioles of the upper leaves reduced. Ultimate divisions of the leaves rounded at the apex, with a minute mucro, glabrous, often pale below, purplish-green. Leaves to +/-8cm broad, +/-6cm long, reduced upwards.

Isopyrum biternatum leafCauline leaf.

Isopyrum biternatum stipulesStipules.

Inflorescence - Single axillary flowers. Flowers becoming more dense near the apex of the stems. Stipules subtending the flowers scarious-purple, rounded, glabrous. Pedicels glabrous, to +/1cm long. Leaves reduced to bracts in the inflorescence.

Flowers - Petals absent. Sepals petaloid. Sepals 5(6), white, glabrous, entire, rounded at the apex, slightly tapered at the base, oblong-elliptic, to +/-1cm long, +/-5mm broad, distinct. Stamens many, +/-50, arising from below the carpels, mostly erect. Filaments white, glabrous, to 4mm long, very thin, clavate. Anthers yellow, globose, .4-.5mm in diameter. Pollen white. Carpels 6, arranged in a ring, green, erect, distinct, glabrous, +/-3mm long in flower. Ovary 1mm long. Style 2mm long. Stigma minute. Receptacle naked.

Isopyrum biternatum flower

Flowering - March - May.

Habitat - Low woods, ravines, flood plains.

Origin - Native to U.S.

Other info. - You know spring has arrived when you start to see this little plant bloom. It adds a splash of white to the understory of woods covered with the drab leaves of fall and winter. The plant forms colonies with its horizontal creeping stems. It is usually associated with other species such as Claytonia virginica, Eyrthronium albidum, and Erigenia bulbosa.
The species name comes from the leaves which are "twice three-times divided" or biternate, (even though some are triternate).

Photographs taken at Whetstone Conservation Area, Callaway County, MO., 3-19-04, and at Eagle Bluffs Conservation Area, Boone County, MO., 3-27-04.


Back