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Recovery Strategy for the Red Mulberry (Morus rubra) in Canada

3. Description of the Species and its Needs

3.1 Species Description

Red Mulberry is a dioecious1, although sometimes monoecious2 understory tree that typically reaches a height of 6 to 18 m (Ambrose 1987). The flowers are wind-pollinated, yellowish to reddish-green catkins3 that bloom in early spring (Ambrose 1987). Red Mulberry trees produce a moderate quantity of deep, red-coloured fruit that mature yearly in mid to late July (Ambrose 1987). The large, heart-shaped leaves are serrate4, long tipped, rough, and hairy and may have one to three lobes. Red Mulberry can be difficult to distinguish from White Mulberry (M. alba) and their hybrids (Ambrose 1987, 1999). Field guides that are representative of Red Mulberry before the introduction of White Mulberry in North America include: Peattie (1950), Braun (1961), Harlow and Harrar (1969) and Tomlinson (1980).

3.2 Species Needs

Across its North American range, the best site conditions for Red Mulberry are found in moist, sheltered coves near streams (Martin et al. 1961). In Canada, the species is native to the Carolinian Life Zone in Ontario. There, it occurs in fresh (damp) to moist, well-drained, forested habitats, including floodplains, bottomlands, the slopes and ravines along the southern portion of the Niagara escarpment and in swales5 on some western Lake Erie sand spits (Ambrose 1999). It occurs on sandy soils in the Essex-Chatham-Kent area and on limestone-based, loamy soils on the Niagara Peninsula (Ambrose 1999). While moderately shade tolerant, forest openings of exposed mineral soil, free of competition, appear to promote better recruitment (Ambrose 1999). Seedlings are sensitive to the heat of summer (Ambrose 1987).

As a wind pollinated species, groupings of trees within the pollen dispersal range are important to ensure the production of sufficient, viable seeds for colonization of new sites. Birds, and possibly small mammals, are important dispersal agents of Red Mulberry fruit (Ambrose 1987).

1 Dioecious plants have male and female flowers on separate plants.
2 Monoecious plants have male and female flowers on the same plant.
3 A catkin is a slender, often drooping, cylindrical flower cluster whose petals are absent or difficult to see.
4 Serrate refers to teeth on a leaf that are notched like a saw and point forward.
5 A swale is a long, narrow, shallow depression, often running parallel to a shoreline, which typically remains moister than bordering ridges of higher land.