Prickly Sida (Prickly Mallow)

Sida spinosa

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Photo of a potted prickly sida plant showing a flower.
The flowers of prickly sida have the stamens united around the pistil, which is a feature common to the mallow family.
Rebekah D. Wallace, University of Georgia, Bugwood.org
Family

Malvaceae (mallows)

Description

A small, much-branched perennial herb with tiny star-shaped hairs. Flowers in leaf axils of upper stems, about 3/8 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.

Size

Stem length: to 2 feet.

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Photo of prickly sida stem tip showing closed flowers and young leaves.
Prickly Sida (Prickly Mallow) (Closed Flowers)
The flowers of prickly sida have a 5-parted structure that is also seen in the fruits.

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Photo of mature prickly sida plants with a yardstick for scale.
Prickly Sida (Prickly Mallow)
Prickly sida was collected from Missouri as early as 1833, but those plants were growing in disturbed sites and were probably introduced.

prickly_sida_in_pot_7-22-14.jpg

Photo of a potted prickly sida plant held for photo by a hand.
Prickly Sida (Prickly Mallow)
Prickly sida, a weedy plant typically seen in disturbed habitats, is in the same family as hibiscus, okra, and hollyhocks.

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Photo of five prickly sida seeds on a fabric background.
Prickly Sida (Prickly Mallow) (Seeds)
The fruit of prickly sida is a flattened ring that splits into 5 wedge-shaped sections, each with a pair of short beaks toward the tip.
Habitat and conservation

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.

image of Prickly Sida Prickly Mallow distribution map
Distribution in Missouri

Common nearly statewide.

Status

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.

Human connections

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.

Ecosystem connections

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.