MORACEAE (mulberry family)

Contributed by Alan Whittemore

Plants trees or less commonly annuals (shrubs or vines elsewhere), monoecious or dioecious, unarmed or (in Maclura) armed with axillary thorns, sometimes producing milky sap. Leaves alternate, petiolate. Stipules present, small, scalelike or herbaceous, often shed early. Leaf blades simple, palmately or pinnately veined, the margins entire or toothed. Inflorescences variously short racemes, spikes, heads, or dense headlike clusters, sometimes the flowers on an expanded receptacle, this variously shaped. Flowers imperfect, actinomorphic, hypogynous, usually subtended by small narrowly lanceolate to narrowly elliptic bracts. Staminate flowers with calyces of 4(5) small, free or united sepals. Pistillate flowers with calyces of 4(5) free or fused sepals, persistent at fruiting and sometimes becoming enlarged and fleshy. Corollas absent. Stamens 4 (absent in pistillate flowers), free, the filaments in our species curved inward in the bud, the anthers attached basally, white to pale yellow, dehiscent by longitudinal slits. Pistil 1 per flower (absent in staminate flowers), of 2 fused carpels or 1 of these failing to develop, the ovary superior, 1- or 2-locular, with 1 ovule per locule, the placentation apical or nearly so. Styles 1 or 2, when only 1 then unbranched or 2-branched. Multiple fruits composed of drupelets or achenes, each subtended by or enclosed in the persistent calyx and either densely spaced or fused into groups of several to many. About 38 genera, about 1,150 species, nearly worldwide.

The Moraceae are a large, important family in the tropics, with few species in the north-temperate zone. They are a complex group and include many genera that do not resemble the temperate mulberries very closely

The fruits of our species of Moraceae are complex in structure, with much of the apparent fruit being accessory tissue (developed from the calyces and bracts of the flowers). The best-known fruits are figs, in which the numerous minute fruits become enclosed within the expanded, fleshy receptacle.

Commercial silk fiber is produced by the pupae of silkworms, which are moths in the genus Bombyx L. (family Bombycidae Latreille), especially B. mori (L.) Silkworm larvae feed only on Moraceae, and persistent efforts through most of the seventeenth and eighteenth centuries to establish a silk industry in the southeastern colonies resulted in the introduction and widespread planting of food plants. The main species used in silkworm farming is Morus alba, the primary food plant for silkworms in the silk-producing regions of China, but some other species of Morus and Maclura are acceptable to the larvae and have been used at times.