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Minnesota Flowering Plants

Common
Name

Scientific
Name

Plant
Family

Native or Introduced

Prime
Season

Glade Mallow
Napaea dioica L.
Mallow (Malvaceae)
Native
Early to Late Summer
Other names and notes

Glade Mallow is an endangered native erect perennial forb growing on stout stems to 6 feet high, with occasional branching in the upper section. Stems are green, ridged and with sparse fine hair. The leaves are alternate and hugh, 4 to 12 inches long and across, somewhat round in outline with 5 to 9 deep palmate lobes which are coarsely toothed with an undersurface that has fine hair with longer hair on the main ribs. All but the very upper leaves are on long stalks. Upper leaves are sessile. At the base of the leaf stalk are a pair of lanceolate shaped leaf-like stipules which wither away as the plant matures. These are quite large for stipules. The inflorescence is a panicle of stalked clusters atop the stem. Each cluster sub-branches into smaller segments. These can be quite large and quite dense. Flowers: Glade Mallow is dioecious - that is - the male and female flowers are on separate plants. The calyx has a short tubular shape with five outward flaring pointed green lobes while the corolla has 5 white deeply cut lobes, ranging from 1/3 to 1/2" across. The lobes are oblong, with rounded tips (sometimes pointed). Calyx lobes and flower stalks have sparse fine hair. The male flowers have numerous stamens, united at their bases, with short filaments and yellowish-tan anthers. These are exerted well beyond the lobes of the corolla. Female flowers have an exerted pistil with a 5-part style. Seed: Fertile flowers produce a globular dark brown seed head with a depressed top that splits into a number of one-seeded flattened wedge-shaped sections, about 5mm long.

Habitat: Glade Mallow grows from a large, corky, branching taproot. It may grow in full sun to partial shade in woodland opening or in full shade under the tree canopy. Plants in full shade will not be robust. In all cases the plant requires moist soil. In the wild it is usually found along stream edges. Names: The genus Napaea is said to come from the word 'nape' for 'of the glade'. The species dioica refers to 'dioecious' - with the sexes on separate plants. The author of the plant description 'L.' is for Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.

Inflorescence Plant
Above and right: The stalked clusters of the inflorescence can be many and very densely filled with flowers. Below and above: Male flowers - sexes are on separate plants.
Flower
Below: The green calyx has some fine hair and 5 pointed triangular lobes. Below: The palmately divided leaf can have 5 to 9 lobes, each lobe with some coarse teeth.
sepals leaf
Right: The underside of the leaf has a fine vein pattern, much paler color due to very fine hair, and a few long whitish hair on the main ribs. leaf underside
Below left: The mature seed head showing the seed divisions. Below right: Individual seeds are wedge shaped with small ribs on the outer circumference.
seed head seeds
Below left: At the base of each branch of the inflorescence are several linear pointed bracts. One of the mature female flowers has started to produce the seeds - you can see the flattened, vertically segmented green seed capsule. Below center: At the base of each leaf are a pair of lanceolate shaped stipules, quite large; these wither away as the plant matures - bottom right.
bracts stipules stem
 
male flowers  

Notes: The Minnesota DNR notes that Glade Mallow is a very old species and is the only dioecious species of the Malvaceae family found in the western hemisphere. It is the only native species of Napaea found in Minnesota or Wisconsin.

Scarcity: Glade Mallow is found in Minnesota only in six counties in the SE corner of the state. Minnesota is at the NW extremity of its range. In North America it is found only in 8 states - Minnesota, Iowa, Illinois, Indiana, Ohio, Pennsylvania, Virginia, Vermont, Wisconsin and also in the District of Columbia. In Indiana it is considered rare, while it is on the 'threatened' list in Minnesota as it has only a few populations and the habitat is becoming more scarce, however, in Fillmore and Olmsted counties there are several large populations in the Root River area.

 
 

 
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applies. Distribution principally from Wi, W2 and 28C. Other sources by specific reference. See Reference List for details.  
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