Circaea canadensis (L.) Hill
Family - Onagraceae
Stems - To +/-30cm tall, erect, herbaceous, simple or branching near the apex, single from a short taproot and fibrous roots, sparse retrorse pubescent, terete.
Leaves - Opposite, petiolate. Petioles to +3cm long, mostly glabrous or with a few antrorse hairs, with a thin shallow adaxial groove. Blades ovate, shallow-serrate, truncate to cordate or rounded at the base, acute to short acuminate. Teeth of blade with a minute whitish apex. Blades very sparse pubescent above and below, to +7cm long, 4cm broad.
Inflorescence - Terminal and axillary racemes to +15cm tall (long). Axis of inflorescence glandular pubescent. Each pedicel sometimes subtended by a minute subulate bract to 1.5mm long.
Flowers - Petals 2, alternating with the sepals, white, notched or rounded at the apex, +/-2.1mm long and broad, glabrous. Stamens 2, erect. Filaments glabrous, white, to 1.7mm long. Anthers whitish, 1.2mm long. Style glabrous, whitish, basally surrounded by a green nectary, to 4mm long. Stigma somewhat bi-lobed. Ovary inferior, densely covered with uncinate hairs, to 2mm long in flower, green. Floral tube short, -1mm long, green, glabrous. Sepals 2, spreading, cupped, ovate, green, 3mm long, sparse glandular pubescent externally, glabrous internally. Fruits shallowly ribbed, with uncinate pubescence, to 4mm long, 2-locular, 2-seeded.
Flower with two small insects in search of nectar.
Flowering - June - August.
Habitat - Rich low woods, thickets.
Origin - Native to U.S.
Other info. - This small but common species can be found throughout Missouri. It is an easy species to ID in the field because of its minute flowers and opposite leaves. The plant can sometimes be found in large colonies in the habitats mentioned above.
Photographs taken in Brown Summit, NC., 6-16-02 (DETenaglia); also along the Duckett Creek trail, St. Charles County, MO, 6-18-2012, and near Aetna, MI, 6-30-2014 (SRTurner).