common mallow

not listed

NNA - Not applicable

SNA - Not applicable

not listed

Common mallow, also called dwarf mallow, is an exotic, weedy, low-growing, herbaceous plant. It is native to Europe, Asia, and North Africa. This and several other species of Malva have been introduced into and are now naturalized in North America. Of these, Malva neglecta is by far the most common. It occurs throughout the United States but is uncommon in the southeast. It is common in Minnesota. It is found on the banks of rivers and streams; on the margins of ponds and lakes; on roadsides and railroads; in fields, pastures, lawns, and farmyards; and in other open, disturbed areas.

Common mallow is an annual, biennial, or perennial forb that rises usually on several stems from a woody taproot. The stems may be branched or unbranched. When there are multiple stems, the outer stems are up to 40″ (1 m) long. They creep along the ground (prostrate) but do not root at the nodes. The inner stems are shorter, 8″ to 16″ (20 to 40 cm) long, sometimes longer, and curve upward from the base (ascending). All stems are sparsely covered with both unbranched (simple) and star-shaped (stellate) hairs. The simple hairs are relatively stout. The stellate hairs are branched at the base into three or more relatively fine, widely spread arms. The stellate hairs wear away with age but the simple hairs persist on older stems.

The leaves are alternate, ⅝″ to 1⅜″ (15 to 35 mm) long, and ⅜″ to 19⁄16″ (10 to 40 mm) wide. The leaf stalks (petioles) are up to 7″ long, 2 to 5 times as long as the blade. At the base of each petiole there is a pair of small appendages (stipules). The stipules are papery, narrowly triangular, ⅛″ to ¼″ (3 to 6 mm) long, and ⅛″ (2.5 mm) wide. They are persistent throughout the growing season. The leaf blades are kidney-shaped or heart-shaped to almost round. They usually have 5 to 7 broad, shallow lobes. They may be flat or slightly wavy and 3-dimensional (crisped) near the margins. The upper and lower surfaces may be hairless or sparsely covered with stellate hairs, especially at the base. The margins are shallowly scalloped (crenate) to sharply toothed with outward-pointing teeth (dentate).

The inflorescence is a cluster of 2 to 6 flowers on long stalks (pedicels) in the leaf axils. When in flower, the pedicels are ascending and several times longer than the whorl of floral leaves at the base of the flower (calyx). When in fruit, the pedicels are drooping, flexible, and curved upward at the tip. At the base of each flower there are 5 small modified leaves (bractlets). The bractlets are linear to narrowly oblong, ⅛″ to 3⁄16″ (3 to 1 mm) long, and 1⁄32″ (1 mm) wide, shorter than the calyx.

Each flower is ½″ to 1″ wide. There are 5 outer floral leaves (sepals, together the calyx), 5 petals, numerous stamens, and 1 pistil. When in flower, the calyx is green, cup shaped, and ⅛″ to ¼″ (4 to 7 mm) long. When in fruit it flattens out and slightly expands to 5⁄16″ (8 mm) long. The lobes are triangular and remain green and herbaceous. They do not have a distinct network of veins. The outer surface is is covered with stellate hairs, and the margin has a fringe of short hairs. The petals are pale violet to white, notched at the tip, and ⅜″ to ½″ (9 to 13 mm) long, about twice as long as the calyx. The veins are not dark but there is often a bold dark streak in the middle and one or two faint streaks on each side. The stalks (filaments) of the stamens are fused for most of their length around the pistil forming a round in cross section reproductive column. The anthers are white.

The fruit is a wheel-shaped, ¼″ in diameter arrangement (schizocarp) of 12 to 15 one-seeded carpels (mericarps). It resembles a tiny wheel of cheese. This is the feature that gives the plant one of its common names, “cheeseweed”. Each mericarp is 1⁄16″ (1.5 to 2.0 mm) long, smooth or weakly ridged, hairy on the back, and rounded on the outer edge.

8″ to 16″

Pale violet to white

Riverbanks, streambanks, pond and lake margins, roadsides, railroads, fields, pastures, lawns, farmyards, and in other open, disturbed areas

June to October

Hollyhock Rust (Puccinia malvacearum)

Sources

2, 3, 4, 5, 7, 22, 28, 29, 30.

Native to Europe, Asia, North Africa, and the Indian subcontinent. Introduced and naturalized in North America.

Common in Minnesota

Malva neglecta was formerly included, along with Malva pusilla and other species, within Malva rotundifolia. The latter name is no longer used.

Plant

Inflorescence

Leaves