The shaddock grows into an awkwardly structured tree with wicked thorns. The fruit is extremely large with very thick, lumpy rind. Some think they are gigantic grapefruits or lemons. The flavor is either bland or sour. Because the fruit is so prolific and large, disposal can be a problem.
Sour oranges are more difficult to recognize as understock because they resemble sweet oranges.
The trees are attractive, but usually taller than sweet oranges and produce long thorns. If mistaken for a sweet orange, considerable effort may be wasted in attempts to encourage production of sweet fruit. Fortunately, other cultivars of citrus are easily grafted onto sour oranges, as well as shaddock. My all-time favorite Citrus is the 'Marsh' grapefruit. Marsh' grapefruits are large and pale yellow with a rich flavor too acidic for many citrus enthusiasts.