Halberd-Leaved Rose Mallow (Hibiscus laevis)

Mallow family (Malvaceae)

Description: This native perennial plant is 3-6' tall, branching occasionally. The stems are round and hairless. The alternate leaves are up to 6" long and 4" across (excluding the petioles). They are divided into 3-5 pointed lobes (cleft) and serrated or crenate along the margins. Leaves with 3 lobes resemble a medieval halberd because the middle lobe is much larger than the 2 sides lobes. Leaves with 5 lobes have the shape of a maple leaf. Some of the leaves may be unlobed, and either sagittate, ovate, or broadly lanceolate. These leaves are hairless, and they have long slender petioles. The upper stems terminate in either a solitary or small cluster of flowers. Each flower is up to 5" across when fully open, consisting of 5 rounded petals, a columnar reproductive structure, and a green calyx with 5 triangular lobes. The petals are white or light pink. The reproductive column consists of whorled stamens and a divided style at its tip. The throat of the flower is usually purple or purplish pink. Around the base of the calyx, there are several narrow bracts. The blooming period can occur from mid-summer to early fall and lasts about a month. Each flower lasts only a single day. The rather large seeds are silky-hairy and irregularly shaped – they tend to be flat-sided and kidney-shaped, but this is not always the case. The fine hairs can be white or brown. The seeds are light for their size, and probably distributed by movement of water. The root system consists of a taproot. This plant spreads by reseeding itself.

Cultivation: The preference is full or partial sun, fertile soil, and wet conditions. Flowers require exposure to sunlight to open up properly. This wetland species doesn't like to dry out.

Range & Habitat: Halberd-Leaved Rose Mallow has been observed in most areas of Tennessee, mainly west. Occasional.

Habitats include marshes, swamps, muddy shores of rivers and ponds, and soggy islands in the middle of rivers or ponds. It is not often found in highly disturbed areas, and doesn't compete well against the invasive Salix interior (Sandbar Willow).

Faunal Associations: The nectar and pollen of the flowers attract bumblebees and oligolectic Emphorine bees that prefer visiting the flowers of Rose Mallows and similar species. In this latter group of bees, are [Close-up of Leaf] such species as Melitoma taurea (The Mallow Bee) and Ptilothrix bombiformis. The caterpillars of the butterfly Strymon melinus (Gray Hairstreak) feed on the flower buds and seeds, while the caterpillars of Pyrgus communis (Checkered Skipper), the moth Eudryas unio (Pearly Wood Nymph), and the butterfly Vanessa cardui (Painted Lady) feed on the foliage. Unfortunately, the troublesome Popillia japonica (Japanese Beetle) is quite fond of the foliage and flowers of Rose Mallows and similar species. Deer and livestock will eat the non-toxic foliage of native Hibiscus spp. readily. However, the introduced shrub, Hibiscus syriacus (Rose-of-Sharon), which is often planted in yards, is apparently more resistant to browsing by deer than the native Hibiscus spp.

Photographic Location: Long Hunter State Park in Middle TN.

Comments: Halberd-Leaved Rose Mallow has large beautiful flowers that can be seen from a distance. The other native Rose Mallow in Illinois is Hibiscus moscheutos (Swamp Rose Mallow). Sometimes the flowers of Swamp Rose Mallow are somewhat larger in size and can span 6-8" across. Some authorities consider Hibiscus moscheutos moscheutos and Hibiscus moscheutos lasiocarpus to be different species, but they both have hairy undersides on their leaves and hairless seeds. In contrast, Halberd-Leaved Rose Mallow has hairless leaves and hairy seeds! An older scientific name for this species is Hibiscus militaris.