trifoliate orange (Citrus trifoliata) — identification, habitat & look-alikes

Trifoliate orange is a thorny shrub or small tree that can escape old plantings and form dense thickets in parts of the southern United States. Each leaf has three leaflets, and its green twigs, fragrant white flowers, and small, fuzzy yellow fruit help identify it. It is also called hardy orange.

Appearance

Appearance: This shrub or small tree grows about 8–20 ft (2.4–6 m) tall. Bright green twigs carry many long, stiff thorns.
Leaves: Each leaf has three leaflets and a winged leaf stalk, unlike the single leaves of most familiar citrus trees.
Flowers: Large white, fragrant flowers open in mid-spring, often before or as the leaves appear.
Fruit: Fuzzy green fruit develops in summer and turns yellow to gold from July through October. The fruit may remain on bare branches into winter.

Look-alikes

Osage-orangeMaclura pomifera

Osage-orange (Maclura pomifera) has single leaves and much larger, wrinkled yellow-green fruit. Trifoliate orange has three leaflets and small, lightly fuzzy citrus-like fruit.

Why they get mixed upBoth can form thorny hedges and bear round yellowish fruit.

Where it lives

Typical habitats: old hedges
woodland edges
roadsides
Range: It is native to China and was introduced to the United States. Dense wild stands are scattered in Texas, Oklahoma, Arkansas, Louisiana, and Georgia, with occasional records elsewhere in the South.
Preferred conditions: It does best in full sun and acidic, well-drained soil. It does not compete well under a closed tree canopy.
Flowering: Flowers Mar–May
Flowers Mar–May · Fruit Jul–Oct

Life cycle

Seed dispersal: Animals spread the many viable seeds, while new stems also arise around the base of established plants.

Cautions

Cautions: The fruit is extremely sour and full of seeds; eating a large amount can cause stomach pain and nausea. Plant juices can also cause skin irritation after sun exposure in some people.

Name and classification

About the name: It was formerly called Poncirus trifoliata.
Varieties and forms: The garden form ‘Flying Dragon’ has strongly twisted stems and thorns. It is a cultivated form of this species, not a separate species here.

Conservation

IUCN Red List: NENot EvaluatedNot yet assessed
Threats: Outside cultivation, it can form dense, nearly impassable stands that crowd open woodland edges in parts of the South.

Culture and stories

Culture and stories: Growers use it as a cold-hardy for grafted citrus.
It was also planted as a livestock and security hedge because the branches knit together and carry formidable thorns.
The fruit has been used for marmalade, although it is much more sour than a sweet orange.

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