Mazus japonicus (Thunb.) Ktze.

Mazus japonicus plant

Family - Scrophulariaceae

Stems - To +25cm long, decumbent to repent, sparse strigose, green or reddish in strong sun, terete, multiple from base, mostly simple.

Leaves - Opposite, petiolate below, sessile above, spatulate, coarse serrate, rounded to subacute at apex, reduced upward, to +/-5cm long, +/-2cm broad, glabrous but ciliate on the margins at the base.

Mazus japonicus leaves

Inflorescence - Long terminal raceme making up most of the stems. Pedicels to 1-5mm long in flower, quickly elongating in fruit to 1cm, mostly glabrous but glandular-strigose on the adaxial surface in one line, expanded near the apex. Each pedicel subtended by a small subulate bract. Bracts to 2-3mm long, scarious in the apical half.

Flowers - Corolla bilabiate, lilac, white, and yellow, 1-1.4cm long, 7-10mm broad, glandular externally, the tube glabrous internally. Upper lip one-lobed, +/-3mm long, 2-3mm broad, tapering at the apex. Lower lip 3-lobed. The lobes rounded. The lateral lobes more broad than the central, whitish-lilac, glabrous internally, 3-4mm long and broad. Central lobe +/-2mm long, thinner than the lateral lobes. Throat of corolla white and yellow spotted, with two pouch-like protrusions. Protrusions bearded with clavate trichomes. Stamens in two pairs, included, adnate near the middle of the corolla tube, each pair converging and the anthers connate. Filaments curved, white, glabrous, +/-4mm long. Anthers yellow, 1mm broad. Style lilac, 6mm long, glabrous. Stigma compressed. Ovary superior, globose, 1.1mm long in flower, purple in the apical half, 2-locular. Placentation axile. Calyx accrescent, quickly expanding in fruit. Calyx tube 1-3mm long in flower, strigose on the veins, 5-lobed. Lobes to 3mm long in flower, subulate, strigose on the midveins, acute. Seeds many, minute, brownish, .4mm long, .2mm broad.

Mazus japonicus calyxCalyx and corolla tube.

Mazus japonicus flower

Mazus japonicus fruitFruit.

Flowering - July - October.

Habitat - Grassy open lawns, roadsides, cultivated fields.

Origin - Native to eastern Asia.

Other info. - This little introduced species is rare in Missouri but will most certainly spread with time. The small flowers are quite striking and the plant is sometimes grown as a rock garden ornamental. It grows easily from seed and many seeds are produced with each fruit.
Many flying insects are attracted to the flowers.

Photographs taken by Tom's Creek, NC., 4-20-03.


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