Ulmaceae

Primary tabs

Ulmaceae

Description

Trees, shrubs or climbers, terrestrial, monoecious (or dioecious), sap watery. Leaves alternate, distichous; stipules free, lateral; blade entire, pinnately veined. Inflorescences in the leaf axils or just below the leaves, bisexual or unisexual, branched or unbranched, bracteate. Flowers unisexual (or bisexual); tepals (3), 4 or 5; stamens (3), 4, 5, or up to 8, straight in the bud; ovary free, unilocular, ovule 1, subapically attached, stigmas 2, entire or furcate. Fruit drupaceous; endosperm lacking or present; cotyledons various.

Distribution

Guianas: present Neotropics: present Pantropical, extending to north- and south-temperate regions: present
Pantropical, extending to north- and south-temperate regions: 15 genera and approx. 150 species; in the Neotropics 6 (or 7) genera and 20-25 species; in the Guianas 3 genera, with one species each.

Wood


Vessels diffuse, solitary and in multiples of 2-5, perforations simple, inter- vascular pits alternate 8-11 μm, vessel-ray and vessel-parenchyma pits slightly larger.
Rays uniseriate and 2-4 seriate, heterogeneous, rhombic crystals sometimes present.
Parenchyma variable.
Fibres non-septate in Ampelocera and Trema, partly septate in Celtis, pits simple.
KEY FOR IDENTIFICATIONFibres in part septate.Celtis iguanaeaFibres non-septate.2Parenchyma aliform-confluent with long and often narrow wings.Ampelocera edentulaParenchyma very scarce, scanty vasicentric.Trema micrantha