Citrus

A broadleaf-evergreen citrus tree reaching 15 to 30 feet tall and wide, with glossy foliage, sharp thorns on its twigs, and highly fragrant white four-petaled flowers. The large fruit (over 3 inches across) ripens pale yellow, often patched with pink, over juicy flesh that ranges from near-white to deep red by cultivar. A subtropical tree hardy only to USDA zone 9a, it is grown outdoors across the citrus belt and as an overwintered container plant farther north.

A vigorous, shade-intolerant small evergreen tree (or large shrub) native to tropical southeastern Asia, grown for very juicy, aromatic green-to-yellow fruit with a thinner rind than Persian lime. Glossy, leathery, distinctively aromatic leaves frame showy five-petaled white flowers - purple-tinged when new - that can appear across all four seasons in warm climates. Strictly tender: NC State lists it for USDA zones 9a-11b, and it does not tolerate standing water, flooding, or shade.

The leading acid citrus - a small broadleaf-evergreen tree to 10 to 20 feet, usually armed with sharp thorns on the twigs, bearing fragrant white flowers (purplish beneath) that ripen into the familiar oval, nipple-tipped yellow fruit dotted with aromatic oil glands. A tender subtropical: hardy outdoors only in USDA zones 9-11, but a classic large-container plant that can summer outside and overwinter indoors in colder climates. Native to Asia, not North America.

Citrus reticulata is the mandarin orange, a small evergreen citrus tree originating from wild populations in South China and Vietnam (the Nanling Mountains region), where domestication occurred at least twice from distinct wild subspecies. In warm climates (USDA zones 9-11) it is a productive, fragrant garden tree bearing the familiar loose-skinned sweet fruits prized worldwide. The honest catch is frost-tenderness: even a light freeze damages the tree and kills young growth, so outside the deep South, coastal California, and Mediterranean climates, it can only be grown as a container plant brought indoors each winter -- a significant maintenance commitment that most gardeners underestimate.

A small subtropical evergreen tree grown for its sweet, fragrant fruit and glossy aromatic leaves. Originally domesticated in subtropical Asia from a cross between a mandarin and a pomelo, it carries clusters of up to six fragrant creamy-white flowers in early spring that ripen into round-to-oval orange fruit 2 to 5 inches across. Hardy outdoors only in the warmest US zones (9-11) but readily grown as a container plant brought indoors for winter in colder climates.