Rotala ramosior (L.) Koehne - Tooth-cup

Rotala ramosior plant

Family - Lythraceae

Stems - From somewhat thickened fibrous roots, erect, herbaceous, branching or simple, 4-angled (the angles rounded), green but becoming red in strong sun, glabrous, to +30cm tall.

Rotala ramosior stem

Leaves - Opposite, decussate, linear-elliptic, sessile, tapering to the base, glabrous, entire, with a single midrib, acute to slightly rounded at the apex, to +3cm long, -1cm broad.

Rotala ramosior leaves

Inflorescence - Single sessile flower from each leaf axil. Each flower subtended by a pair of opposite minute bracts. Bracts to +/-3mm long, 1mm broad, glabrous.

Flowers - Petals 4, pink to rose, adnate at the apex of the hypanthium, orbicular, 1-2mm in diameter, glabrous, alternating with the calyx appendages. Stamens 4, adnate in the middle of the calyx tube, included. Filaments 1mm long, greenish, glabrous. Anthers yellow, .1mm long. Ovary superior, globose to subglobose, to 3mm long, glabrous, 3-locular. Placentation axile. Ovules many. Style 1, to -1mm long, glabrous. Stigma small-capitate. Calyx tube green to red (in sun), glabrous inside and out, 1mm long in flower and quickly expanding, with 4 lobes and 4 triangular appendages. Lobes acute, glabrous, mostly green, lanceolate, to +1.5mm long, -1mm broad. Appendages triangular, -1mm long and broader than long.

Rotala ramosior hypanthium

Rotala ramosior flower

Flowering - June - October.

Habitat - Margins of streams, spring branches, sloughs, oxbows, ditches, moist ledges, wet areas of prairies.

Origin - Native to U.S.

Other info. - This small but attractive species can be found in the southern 2/3 of Missouri. The plant is easy to identify becasue of its tiny, 4-petaled flowers and its habitat.

Photographs taken in the Ozark Scenic Riverways, Shannon County, MO., 7-28-04, and off Lee Rd. 27, Auburn, AL., 9-15-05.


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