Morus rubra (Red Mulberry)
|Also known as:|
|Life cycle:||perennial woody|
|Habitat:||part shade, shade, sun; moist; floodplain forest, woodland edges, rocky slopes|
|Bloom season:||May - June|
|Plant height:||25 to 80 feet|
|Wetland Indicator Status:||GP: FACU MW: FACU NCNE: FACU|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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Male and female flowers are borne separately, usually on different trees (dioecious), in clusters called catkins, 1 to a few catkins emerging from buds along 1-year-old branches at about the same time as the leaves. Male catkins are ascending to pendulous in flower, ¾ to 2+ inches long, green to yellowish, each flower in the cluster with 4 stamens.
Female catkins are erect to ascending and more compact, oval to short-cylindric, to ¾ inch long, each flower with a somewhat flattened, oval green ovary and a whitish to reddish, 2-parted style. Cluster stalks on both male and female catkins are hairy.
Leaves and stems:
Leaves are alternate and simple, usually unlobed or sometimes irregularly 2 or 3-lobed (rarely more), most lobes with rounded tips, the leaf or terminal lobe abruptly tapering to an extended, sharply pointed tip (acuminate). The blade is oval to egg-shaped in outline, 4 to 7+ inches long, 3 to 5 inches wide, on a hairy stalk about 1 inch long. Edges are coarsely toothed often with rounded teeth, the upper surface dull dark green, slightly rough textured, the lower surface lighter green and hairy across the surface and more densely hairy along the veins. Three major veins radiate from the base where the stalk meets the blade.
New twigs are green to reddish-brown with scattered, raised lenticels (pores), and hairless to minutely hairy; hairs can persist through the second year. Bark is thin and somewhat rough, turning brown to orange-brown with maturity. Twigs and leaves exude a milky sap when cut.
Female catkins become nodding to pendulous fruit clusters, 3/8 to 1+ inches long, resembling elongated raspberries or blackberries. The color of fruit ranges from white to pink to red, but all turn purplish-black when mature.
Red Mulberry is considered historic in Minnesota, first collected in 1899 near Jefferson in southeast Houston County, then again in 1920 in the same area but with no confirmed reports since. In 2014, claims of two locations along Hwy 26 between Reno and Brownsville were reported but our search of that area only came up with the non-native White Mulberry (Morus alba), so we question the validity of those reports. The two species are known to hybridize, which complicates matters, and the hybrid has been recorded in Minnesota scattered across our southern counties and as far north as Sherburne county (see the county distribution map on the White Mulberry page).
Red and White mulberries may be easily confused. While the leaf shape of both species can be quite variable, Red Mulberry usually has (mostly) unlobed leaves that are dull and somewhat rough on the upper surface and hairy on the lower, while White Mulberry leaves are (mostly) 3 to 7-lobed, smooth and shiny on the upper surface, hairy only along the veins on the lower, and tend to be smaller (max 4 inches long vs. 7 inches). White Mulberry twigs and bark also tend to be more orange than Red Mulberry. The hybrid is not well-documented but is likely intermediate between the two. Unlobed Red Mulberry leaves may also resemble Basswood or Linden (Tilia species), which have asymmetrical leaf bases and very different flower clusters and fruits with a distinctive leafy bract.
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- Red Mulberry tree
- Red Mulberry tree
- bark of young tree
- leafy branch
- leaf scan
- hairs on leaf underside
- flowering branch
Photos by K. Chayka and Peter M. Dziuk taken in Louisiana.
Have you seen this plant in Minnesota, or have any other comments about it?