Ruellia humilis Nutt. - Wild Petunia

Ruellia humilis plant

Family - Acanthaceae

Stems - Erect, herbaceous, often purplish in strong sun, single or multiple from the base, 4-angled, hirsute to hispid, from short rhizomes, to +/-40cm tall, branching.

Ruellia humilis stem

Leaves - Opposite, sessile, ovate to ovate-lanceolate, densely long pubescent above and below, entire, subacute at apex, decussate, to +/-4cm long, +/-2.2cm broad. Margins often slightly wavy.

Ruellia humilis leaves

Inflorescence - Flowers sessile in upper leaf axils, subtended by 2 opposite foliaceous bracts. Bracts pubescent as the leaves.

Flowers - Corolla tube to +5cm long. Contracted portion of tube -4cm long, tan, pubescent. Expanded portion of corolla typically lilac, -2cm long, 5-lobed. Lobes rounded, +1cm long, mostly glabrous. Central lower lobe with purple veins. Stamens 4, didynamous, adnate at apex of contracted portion of corolla tube. Filaments white, +/-1cm long, glabrous. Anthers lilac to tan, +3mm long. Style +/-5.5cm long, white to lilac, sparse pubescent (mostly at base). Stigma purple, flattened, 2-3mm long. Ovary green, glabrous, superior, cylindric, 2-locular. Placentation axile. Fruit glabrous. Calyx tube to 2mm long, 5-lobed, green, glabrous. Lobes to 2cm long, 1mm broad at base, linear-attenuate, ciliate-margined. The cilia to 2-3mm long, multicellular. Calyx accrescent.

Ruellia humilis calyxCalyx.

Ruellia humilis corollaCorolla tube.

Ruellia humilis corollaCorolla.

Flowering - May - October.

Habitat - Dry prairies, glades, open rocky woods, bluffs.

Origin - Native to U.S.

Other info. - This species can be found throughout Missouri.
The plant is incredibly variable in its pubescence and flower size and many varieties have been named. Much integration occurs between these varieties so I won't name them here.
This species is actually edible and is enjoyed by grazing animals.

Photographs taken near Springfield, MO., 7-4-03.


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