Culture
Grow in average, medium moisture, well-drained soils in full sun. Prune as needed after flowering. May not be reliably winter hardy in northern parts of USDA Zone 5 where it should be sited in a protected location.
Noteworthy Characteristics
Poncirus trifoliata, commonly called hardy orange, a citrus relative, is a thorny, well-branched, deciduous shrub or small tree which typically grow 8-15' (less frequently to 20') tall. Three-lobed (trifoliate as per the species name) leaves emerge yellowish-green in spring, turn glossy dark green in summer and fade to yellow in autumn. Spiny, dark green stems. Fragrant, white, 4-7 petaled flowers (to 2" diameter) appear singly in spring. Flowers give way to 1-2.5" diameter fruits (miniature downy hardy oranges) which ripen to an attractive yellow in the fall. Fruits of this citrus relative are edible (lemony flavor), but are very acidic and seedy. Fruits can used to make marmalade (use peel zest and pulp), but are usually left on the tree where they persist well into winter and often provide significant ornamental interest.
Genus name comes from the French word poncire a kind of citron.
Specific epithet refers to the three-lobed leaves.
'Monstrosa' typically grows 3-6' tall and features zigzag to corkscrew stems, curved thorns (to 1" long), slightly fragrant 4-7 petaled white spring flowers (to 2" diameter) and yellow-orange autumn fruit (to 2" diameter). This cultivar is synonymous with and sometimes sold as P. t. 'Flying Dragon'. 'Monstrosa' is somewhat reminiscent of the European filbert cultivar known as Harry Lauder's walking stick (Corylus avellana "Contorta") in that both cultivars are semi-dwarf, contorted-stem versions of their respective species plants.
Problems
No serious insect or disease problems. Thorns are vicious.
Uses
Specimen, small grouping or impenetrable hedge with good year round interest. This cultivar is an unusual plant which needs a prominent placement around the home so that the excellent ornamental features, particularly the contorted stems, can be enjoyed. As a hedge, this thorny shrub is the botanical equivalent of a barbed wire fence.