Moraceae

Growth Form and Habit

Mostly evergreen or deciduous trees and shrubs, some are lianas (climbers, often root climbers or stranglers like many Ficus), rarely herbs. Plants typically produce milky latex (sap), sometimes clear or yellowish, in specialized cells or canals (laticifers) throughout the plant.

Leaves

Leaves are usually simple and arranged alternately and spirally (rarely opposite). Leaf blades are variable in shape, often entire but frequently palmately lobed (especially in Morus, Broussonetia, juvenile Ficus) or sometimes pinnately lobed. Venation is pinnate or palmate. A key feature is the presence of stipules, typically paired and often large, which enclose the terminal bud. These stipules are usually deciduous, falling off early and leaving behind characteristic annular (ring-like) scars that encircle the twig at each node.

Typical Moraceae twig showing alternate simple leaf and characteristic stipule scar encircling the node.

Inflorescence

Flowers are always unisexual and typically densely aggregated into specialized inflorescences, which vary among genera:

• Syconium (Ficus): A unique, fleshy, urn-shaped or globose receptacle that is entirely enclosed except for a small apical opening called an ostiole, which is lined with small bracts. Tiny male and female flowers line the inner cavity. Pollination occurs via specialized fig wasps that enter through the ostiole.
• Spikes or Racemes: Often catkin-like, dense spikes or racemes bearing either male or female flowers (Morus, Broussonetia).
• Globose Heads: Dense spherical heads bearing numerous male or female flowers (Maclura, some Artocarpus).
• Discoid Receptacles: Flattened, disc-like receptacles bearing flowers (Dorstenia).

Unique syconium inflorescence of Ficus: a fleshy receptacle enclosing tiny unisexual flowers on the inner surface.

Flowers

Flowers are small, inconspicuous, unisexual (plants monoecious or dioecious), actinomorphic, and typically lack petals (apetalous). Wind pollination occurs in some (Morus), but specialized insect pollination (e.g., fig wasps in Ficus) is common.

• Perianth: Usually composed of 4-5 (sometimes 0-8) small, distinct or basally fused, sepal-like tepals. Often persistent and sometimes becoming fleshy and part of the multiple fruit.
• Androecium (Male Flowers): Stamens usually number as many as (and opposite to) the tepals (typically 4, sometimes 1-8). Filaments are sometimes inflexed (bent inwards) in bud and spring outwards elastically to release pollen (Morus). Anthers open by longitudinal slits. Pistillode may be present or absent.
• Gynoecium (Female Flowers): Ovary is usually superior (sometimes inferior or embedded in receptacle), typically composed of 2 fused carpels but usually appearing unilocular by abortion or suppression. Contains a single apical or basal ovule. Styles usually 2 (sometimes 1), often slender or feathery.

Fruits and Seeds

The individual fruit is typically a small achene or drupe. However, because the flowers are densely clustered, the mature fruits, along with associated fleshy perianths and/or receptacle tissue, typically fuse together to form a multiple fruit (syncarp). The structure of the syncarp reflects the inflorescence structure:

• Mulberry (Morus): An elongated syncarp formed from fleshy perianths surrounding individual drupes/achenes.
• Osage Orange (Maclura): A large, globose, bumpy syncarp formed from fleshy receptacles and perianths surrounding drupes.
• Fig (Ficus): The fleshy syconium itself, containing numerous tiny achenes (the true fruits) on the inside.
• Breadfruit/Jackfruit (Artocarpus): Very large syncarps formed from the entire inflorescence.

Seeds contain fleshy endosperm (sometimes scant) and often a curved or folded embryo.

Chemical Characteristics

The presence of laticifers producing milky latex is characteristic of most members (though sometimes watery or sparse). The latex contains various compounds including triterpenes and sometimes alkaloids or cardiac glycosides (Maclura). Tannins and flavonoids are also common.