Acalypha ostryaefolia Riddell - Three-Seeded Mercury

Acalypha ostryaefolia plant

Family - Euphorbiaceae

Stems - From a single taproot, erect, branching, herbaceous, often purplish with green vertical striations, glandular pubescent and with vertical lines of tomentoulose hairs extending downward from the leaf petiole bases, to 40cm tall.

Acalypha ostryaefolia stem

Leaves - Alternate, petiolate. Petioles to +/-4cm long, puberulent and with some glandular pubescence near the apex, often reddish near the apex. Blades cordate at the base, ovate, acute at the apex, evenly serrate, to +5cm long, 3cm broad, sparse pubescent above and below. Blades appear peltate because of the strongly cordate base.

Acalypha ostryaefolia leavesPressed leaves.

Inflorescence - Staminate inflorescences axillary, short pedunculate, cylindric, to +/-1cm long. Peduncles tomentose, 3mm long. Flowers dense, with a glabrous pedicel to .3mm long. Pistillate inflorescence terminal, cylindric, sessile, to +/-1.5cm long in flower, quickly elongating in fruit. Flowers dense, sessile. Each pistillate flower subtended by a sessile bract to 1.5mm broad. Bracts 10-lobed (or 5-lobed and the lobes divided), green. Lobes of the bracts linear, .6-.7mm long, aristate. Base of the bracts strigose.

Acalypha ostryaefolia inflorescence

Flowers - Staminate flowers with 4 translucent to green sepals. Sepals ovate, .4mm long, acute, often with some red tinge. Pistillate flowers with 3 styles. Styles deeply divided into long-attenuate to hairlike divisions to 3mm long. The divisions whitened in the apical 1/2. Ovary green, globose, 1mm in diameter in flower, with green papillae on the surface.

Acalypha ostryaefolia flowersStaminate flowers close-up.

Acalypha ostryaefolia flowersPistillate flowers.

Acalypha ostryaefolia fruitsInfructescence.

Acalypha ostryaefolia seedsSeeds.

Flowering - June - October.

Habitat - Moist open ground, fallow ground, cultivated areas, waste ground, roadsides, railroads.

Origin - Native to U.S.

Other info. - This weedy species can be found in the southern half of Missouri. The plant is easy to identify because of its cordate leaves, which appear peltate, and its terminal spike of pistillate flowers.
In cultivated areas and disturbed sites the plant can form large colonies.

Photographs taken in Van Buren, MO., 7-18-03.


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