Prickly Sida (Prickly Mallow)

Photo of a potted prickly sida plant showing a flower.
Scientific Name
Sida spinosa
Malvaceae (mallows)

A small, much-branched perennial herb with tiny star-shaped hairs. Flowers in leaf axils of upper stems, about ⅜ inch across, with 5 yellow to orange-yellow petals; the stamens are united around the pistil (a feature of mallows). Blooms June–October. Leaves alternate, on long stems, ovate to oblong with crenate (scalloped) margins. Leaf stems have at their bases a small, spinelike projection, which is quite soft until the plant matures and dries out. Fruit a flattened ring that splits into 5 wedge-shaped sections (mericarps) each with a pair of short beaks toward the tip.

Similar species: Elliott’s sida (S. elliottii) grows on Crowley’s Ridge in southeast Missouri. It has 10 mericarps, flowers solitary (not clustered) in the leaf axils, and leaf stems shorter (not longer) than the accompanying flower stalk. Also, the weedy, introduced arrowleaf sida (S. rhombifolia) may soon be found in Missouri. It has only 1 beak per mericarp.


Stem length: to 2 feet.

Where To Find
image of Prickly Sida Prickly Mallow distribution map

Common nearly statewide.

Occurs on banks of streams and rivers, margins of pond and lakes, rarely savannas; also roadsides, railroads, edges of crop fields, pastures, and open, disturbed areas. Most likely introduced to our state. It’s a native of the New and Old World tropics.

A close look at the flowers, with the columnlike pistil with united stamens attached to it, shows this plant’s relationship to other mallows such as hibiscus, cotton, okra, and hollyhocks.

Biogeography is the study of how life forms are distributed spatially, across the land. The northern extent of this plant’s historic, native range is unclear. It was collected from our state as early as 1833, but those plants were growing in disturbed sites, so they were probably introduced.

Bees, butterflies, and skippers drink nectar from the flowers. The spiny projections on the seeds help them adhere to the fur of animals, which enables the new plants to disperse from the parent plant.

Media Gallery
Similar Species
About Wildflowers, Grasses and Other Nonwoody Plants in Missouri
A very simple way of thinking about the green world is to divide the vascular plants into two groups: woody and nonwoody (or herbaceous). But this is an artificial division; many plant families include some species that are woody and some that are not. The diversity of nonwoody vascular plants is staggering! Think of all the ferns, grasses, sedges, lilies, peas, sunflowers, nightshades, milkweeds, mustards, mints, and mallows — weeds and wildflowers — and many more!