Trifoliate Orange/Hardy Orange

Basic Information
Tree ID: 
Genus and species: 
Flying Dragon
This tree is a short, hardy, shrub-like tree native to Northern China and the Korean Peninsula that can be found near the short chain-link fence in the Marsh Gardens. It has corkscrew-like branches that are barbed and is also referred to as the Chinese bitter orange. This tree blooms in the spring and bears fruit in the fall (the fruit is pubescent (downy), citrus-like and great in a gin and tonic).
Austin Igelman
Collected Data
Tree shape: 
Date of tree entry: 
1.65 m
Smooth bark with occasional large thorns. Dark brown to grey with green, photosynthetic "stripes" running along the branch (in the direction of the grain).
Twigs & branches
Green, smooth with many large, pointed thorns (also green). Branches are not straight, but rather are curved and bent. This forms a thick webbing of branches and thorns.
Dark green, obovate shaped leaves. Palmately compound with three (and, rarely, five) leaflets. Like other citrus, the leaves smell spicy when crushed.
Reproductive Structures
White, palmate-like flowers. Yellow stigma and anthers. Citrus like and quite fragrant.
Yellow when ripe, green before ripe. Citrus looking, but downy rather than pulpy fruit. The taste is said to be cross between a lemon and a grapefruit. Fruit is on the small side as compared to normal citrus fruit.
  • Spring
  • Summer
  • Autumn
  • Winter
Natural range of distribution: 
The hardy or trifoliate orange originated from Northern China and the Korean Peninsula but can now be found in both Europe and North America. In North America, it is mostly found in the southern United States. It, as the name implies, is quite a hardy plant that can withstand even the harshest of New England winters. It prefers direct sunlight but is not necessary for its growth. In terms of soil, the trifoliate orange sandy to loamy soil and high levels of moisture. In a less "natural" environment, it is often found in hedges. The thorny nature of the trifoliate orange has made it an ideal hedge plant for homeowners. It is even known to be used to keep livestock in fields. It is often found in North American forests, especially at the edges of the woodlands. The "natural" (outside of intentional plantings) range of the trifoliate orange in the United States is shown in the picture above.
Origin, history, and uses: 

The trifoliate orange originated in Northern China and the Korean Peninsula.  However, it has become common in parts of the southern United States. In the US, it has been cultivated as a plant for hedges as the thorns dissuade possible intruding animals.  In traditional Eastern Medicine, the fruit is used to remedy allergic reactions especially inflammation.  The fruit is edible though not widely consumed in the Western world.  Modern in vitro lab experiments have suggested that extracts from the trifoliate orange can be processed to be used as an antiallergenic and antiinflamitory. The trifoliate orange was traditionally made into jams, jellies and marmalades by early American colonists. 

The trifoliate orange follows fairly typical seasonal patterens of flowering trees. It loses its leaves in the winter, blooms in the spring and has ripened fruit come the fall. Much of the bark and branches of the trifoliate orange, however, stays green yearround. This provides a remarkable contrast during the winter with the rest of the garden and plant-life which is predominantly brown in the cold, brutal New England winters. Leaves tend to begin to show on the plant in the spring as do the flowers. The flowers are small, white, and very fragrant. Fruit may begin to show in the summer and are green when unripe. As the fruit ripens, they turn from green to yellow and the ripe fruit is ready by the fall.
“Citrus Pages / Trifoliate Orange.” Citrus Pages / Trifoliate Orange. Citrus Pages, n.d. Web. 21 Apr. 2014. <>.
Deane, Green. “Hardy Orange.” Eat The Weeds and Other Things Too RSS. N.p., n.d. Web. 21 Apr. 2014. <>.
Keim, Richard. “Louisiana Plant ID | Poncirus Trifoliata (trifoliate Orange).” Louisiana Plant ID | Poncirus Trifoliata (trifoliate Orange). LSU, 20 Sept. 2013. Web. 21 Apr. 2014. <>.
“Poncirus Trifoliata Fact Sheet.” Poncirus Trifoliata Fact Sheet. Virginia Tech, 2012. Web. 21 Apr. 2014. <>.
“ - Home.” Texas Invasives. Texas Invasives, 29 Jan. 2001. Web. 21 Apr. 2014. <>.
Other information of interest: 
Media and Arts
Yale's own Eric Larson talks about this specific hardy orange

This specific trifoliate orange plant originates from the Forest Farm Nursery in Southern Oregon.  I actually grew up in Southern Oregon less than an hour from the Forest Farm Nursery.  This past spring (2014) I decided to make a pilgrimage to the birthplace of this amazing tree.  This nursery contains an incredibly diverse array of plant species (over 5000 selections!).  The staff at the nursery was friendly, knowledgeable and helpful and showed me their stock of trifoliate oranges.  The environment was quite stimulating and the staff were more than happy to talk about the plants and ask how their hardy orange was doing over 3000 miles away in New Haven.  The currently had several trifoliate oranges in stock; though they said they were not a particular popular item.  I thought the individuality and character that seems to radiate from this small tree in New Haven is remarkably similar to the aura that I experienced at the Forest Farm Nursery.  If any of you are ever in Southern Oregon, traveling slightly off the beaten path to the Forest Farm Nursery will be sure to entertain; even for those who are not plant aficionados.  I would highly recommend stopping by to at least look around and talk to the staff.  You never know what you might find.  Above, in the section marked “other information of interest” is a link to the nursery’s website and I will put the link below as well.

Mit freundlichen Grüßen

Austin Igelman