North American Flowering Plants

Swamp Rose is an erect perennial shrub, growing 3 to 6 feet high, with multiple stems and some branching so that the height equals the width, with smooth reddish arching stems that have stout thorns that have a wide base and a downward curve. On the upper stem, thorns are few and usually near leaf nodes, but the lower stem may have many prickles but less stout. New growth will be greenish before turning to reddish.

The leaves are alternate and pinnately compound with an odd number of leaflets, usually 3 pair of laterals and a terminal leaflet, but the number can vary from 5 to as many as 9 leaflets. The leaf stalk is reddish with fine hair. Each leaflet has a short stalk but occasionally only the terminal leaflet will be stalked. The leaflets are broadly elliptic with a central main vein and ascending lateral veins. Edges have serrated teeth, the most of any North American wild rose, but the lower 1/4th of the leaflet is usually without teeth. The upper surface is a darker green, the underside paler. The terminal leaflet and the the pair of laterals below the terminal leaflet will be the same shape but longer (up to 2-1/2 inches) and wider than those below. Leaflet tips are pointed. At the base of the leaf stalk is a pair of narrow stipules fused to the stalk except for the upper ends which diverge into pointed triangular tips.

The inflorescence is a single flower or a small cluster of stalked flowers at the tip of new growth.

The flowers are perfect, slightly fragrant, up to 2+ inches across with 5 pink petals, ovate to oval in shape, widest near the rounded tip. The receptacle or base, forms a cup-shape and has 5 calyx lobes (sepals) that are lanceolate in shape with long tapering tips. These are usually persistent on the fruit as it forms. The flower stalk, the receptacle and the underside of the calyx lobes are covered with reddish glandular tipped hairs. The reproductive parts in the corolla consist of the central yellow receptacle with densely clustered styles rising from 24 to 50 carpels. The receptacle is surrounded by a ring of numerous stamens, flattened toward the petal surface. These have yellow filaments and slightly darker yellow anthers.

Fruit: Flowers mature to a smooth fleshy red rose hip, up to 1/2 inch in diameter, that contains numerous achenes (the true seeds). Wild Rose seeds should be sown outside in the Fall. They will germinate in the 2nd year as they need a cold moist period followed by a warm moist period followed by another cold moist period. If seed has been stored for the proper sequence of periods then it should be scarified before planting. Fall planted fresh seeds should not be scarified. While seed is cheap, bare root plants are usually available from native plant nurseries.

Habitat: Swamp Rose grows in the moist soils of marshes, swamps and riparian areas where there is adequate moisture, full sun, and typically more acid soils. The plant will tolerate some shade and can be grown in more upland sites if adequate moisture is provided. The root system is woody to woody rhizomatous with a tap root, and can produce suckering.

Names: The genus Rosa is Latin for 'rose'. The species name, palustris, means 'marsh-loving.' The author name for the plant classification, ‘Marshall’ is for Humphry Marshall (1722-1801), American Botanist, who published this plant description in 1785 in - Arboretum Americanum: The American Grove, an Alphabetical Catalogue of Forest Trees and Shrubs, Natives of the American United States.

Comparisons: Many Wild Roses have similar appearances, especially in the flowers. Look for the amount and shape of prickles, the number of leaflets, the type of flower cluster and the presence or absence of glandular hair. Here is a comparison chart for 6 other wild roses that are native or can grow in Minnesota - Chart. Only the Carolina Rose and the Climbing Rose, R. setigera, have comparable glandular hair on the flower buds, calyx and receptacle. Swamp Rose is one of the latest blooming wild roses.