Common Name: Yellowhorn, Goldenhorn, Chinese Flowering Chestnut, Wen Guan Guo
Scientific Name: Xanthoceras sorbifolium
Family: Sapindaceae (the Soapberry, Maple, and Lychee family)

Yellowhorn07

The edible seeds are about the size of a pea 0.6 inches (1.5 cm) and are high in oils.

Description:
I was asked by a reader to write an article about Yellowhorn since they were having some trouble growing this plant. I had heard of this plant before, but other than a name, I couldn’t have told you much more. I love to research plants that I don’t know much about, and Yellowhorn is just that. As it turns out, there doesn’t seem to be anyone (that I can easily find) that knows a lot about Yellowhorn either. I know that there are probably some brilliant Chinese, Korean, and Russian botanists who could tell me all I ever wanted to know about this interesting plant, but they don’t seem to be the type that publish their work online. So I dug as deep as I could into my library, the botanical literature, and online gardening, forestry, permaculture, and even stock market message boards to try and develop as complete an article as I could on Xanthoceras sorbifolium, also known as Yellowhorn, or Wen Guan Guo in China.

This deciduous shrub or small tree is slow-growing, but once established it will produce edible, dark green leaves that turn bright yellow in Autumn. It has beautiful, fragrant flowers that are also edible, and seeds that are used for food and cooking oil. The oil is also being evaluated for biodiesel. This ornamental plant is also fairly drought tolerant and may also be a food source for beneficial insects. It is almost unknown outside of Asia, but this plant seems to be growing in popularity. While Yellowhorn will make an interesting and useful addition to a Forest Garden, I think there is a lot of potential for this as a major crop.

Yellowhorn11

Xanthoceras sorbifolium Bunge
Curtis’s Botanical Magazine, vol. 113 [ser. 3, vol. 43]: t. 6923 (1887) [M. Smith]

History:
Native to northern and northeastern China. It has also been growing in Korea for so long, we may not know if it is a native or was imported there. Yellowhorn was cultivated in Russia since the 1920’s and was introduced to France in 1866 via a French missionary who visited China. It has only recently become more available outside of Asia, and it is being sold mainly as an ornamental. It seems that there was some work with this plant in China on the Loess Plateau (this rehabilitation story is told in the amazing documentary Hope in a Changing Climate by John Liu).

Here is one of the earliest accounts I can find of this plant:

I first saw a plant of Xanthoceras at Baden-Baden on the grounds of Herr Max Leichtlin about the year 1884. I admired it, and Herr Leichtlin spoke of it as a new plant of great promise, which he felt sure would be an acquisition to horticulture. I secured two plants, and have been cultivating them now for eight or ten years. They are six feet high, and grow in rich warm loam. They have no protection whatever, and yet they have never lost a branch in winter, and they endure our dry summers perfectly. They are not strong-growing shrubs, but they bear flowers in great profusion, and are more beautiful when in bloom than at any other season. They ripen seeds every year, and I would be glad to furnish some of them to any one who cares to test the plant.
– Paul Dana, Dosoris Park, Long Island (1893)

Trivia:

  • The genus name, “Xanthoceras” means “yellow horn”. This is in reference to the orange-yellow, horn/claw-like appendages between the petals.
  • Yellowhorn fruit is green, round to pear-shaped, and up to 2.5 (6 cm) long.
  • The fruit splits into three sections to release the seeds.
  • There are 6-18 seeds per fruit, and each seed is about the size of a pea 0.6 inches (1.5 cm). The seeds are brown to purplish in color.
  • The flowers are white, about 1 inch (2.5 cm) in diameter, and the yellow center will change to red/maroon when older (once source states that the color change occurs after pollination).
  • One source stated that the fruit is 40% oil, and the seed alone is 72% oil (60% of which is Omega 6).
The young leaves are edible and the fruit can be round or pear-shaped.

The young leaves are edible and the fruit can be round or pear-shaped.

USING THIS PLANT

Primary Uses:

  • Edible Nut (Seed) – reports on flavor vary from a Sweet Chestnut to a Brazil nut or a Macadamia nut. Can be roasted, boiled, or dried and ground into a flour. One soure states that the nuts taste fine raw.
  • Edible Leaves – young leaves can be cooked, traditionally boiled. Leaves quickly become fibrous.
  • Edible Flowers – cooked, traditionally boiled
  • Flour – dried nut can be ground into a flour and then cooked
  • Oil – edible oil can be pressed from the seeds (one source stated it was being evaluated for biodiesel).

Secondary Uses:

  • General insect (especially bees) nectar plant – this statement was only made by one source
  • Ornamental Plant – long lasting, deep green leaves; large masses of pretty, fragrant flowers
  • Drought Plant – this species can tolerate prolonged dry conditions once established

Yield: A single source stated that fruit (nut?) yield can reach 8 tons (7260 kg) per acre, and oil yield can be 850 gallons (3200 liters) per acre.
Harvesting: Early to Mid-Autumn (September-October). Harvest when the fruits dry out, but before the fruit splits.
Storage: Seeds need to be dried for storage.

The beautiful flowers can cover the plant.

The beautiful flowers can cover the plant.

The flowers are fragrant.

And the flowers' center starts off yellow and will fade to red.

The center of the flower starts off yellow and will fade to red.

DESIGNING WITH THIS PLANT

USDA Hardiness Zone: 4-7
AHS Heat Zone: No reliable information is available, although it does seem to like long, hot Summers.
Chill Requirement: Likely considering where this plant originates, but no reliable information is available.

Plant Type: Large Shrub or Small Tree
Leaf Type: Deciduous
Forest Garden Use: Sub-Canopy Layer, Shrub Layer
Cultivars/Varieties: Yes… however, there is very little information on them.

Pollination: Some sources state that Yellowhorn is self-fertile and some say that it requires cross-pollination. Likely, it is partially self-pollinating but will produce significantly more fruit if allowed to cross-pollinate. It is reported that there are both male flowers and bisexual (hermaphroditic) flowers found on the same plant, but not the same inflorescence.
Flowering: Mid-Late Spring to Early Summer (April-June)

Life Span:

  • Years to Begin Fruiting: No reliable information can be found, but a few sources stated that Yellowhorn will bloom at an early age. A single source stated that flowering will begin during the second year, most sources say year three.
  • Years to Maximum Height: 10-20 years
  • Years to Maximum Fruiting: A single source stated that maximum yield will start at around 5 years of age.
  • Years of Useful Life: No reliable information can be found, but one source stated that Yellowhorn can live for over 200 years of age.
The fruit will dry on the tree and release its seed if allowed.

The fruit will dry on the tree and release its seed if allowed.

The fruit can be harvested while the fruit is still green.

The fruit can be harvested while the fruit is still green.

But it seems that most will wait until the fruit starts to turn brown to begin harvest.

Most growers will wait until the fruit starts to turn brown to begin harvest.

The seeds are edible and are used to make a cooking oil.

The seeds are edible and are also pressed to make a cooking oil.

PHYSICAL CHARACTERISTICS OF THIS PLANT

Size: 6-24 feet (2-7.3 meters) tall and wide
Roots: No reliable information is available, but one source states that Yellowhorn puts down a “very large root”… this could mean that Yellowhorn has a taproot. Another sources states Yellowhorn has “long, fleshy roots with fibrous developments mostly at the end.” I think we can assume that this plant has deep growing roots, either single or few in number.
Growth Rate: Slow

Yellowhorn will turn a brilliant yellow in Autumn.

Yellowhorn will turn a brilliant yellow in Autumn.

Yellowhorn (right) is edible and closely related to the Horse Chestnut (left) which is poisonous.

Yellowhorn (right) is edible and closely related to the Horse Chestnut (left) which is toxic to humans and many animals.

GROWING CONDITIONS FOR THIS PLANT

Light: Prefers full sun
Shade: Tolerates light shade
Moisture: Prefers medium moisture soils, but tolerates dry soils once established
pH: 5.5-8.5

Special Considerations for Growing:

  • Yellowhorn does best in climates that have hot and dry Summers, and should be protected from cold winds.
  • If this plant does have a taproot (information on root structure is scarce), then it should be planted in place as soon as possible. The numerous reports of growers having little growth with this plant and then it took off after it was planted in its permanent location, and plants doing poorly when kept in pots, supports the idea of it having a taproot(s).

Propagation:
Various sources give different information… some say that seeds are not dormant and germinate well without any special treatment and others state that they need at least 3 months of cold stratification. Likely, both are accurate, and this plant can grow without stratification, but germination rates are probably higher with some exposure to cold for a few months as would occur in its natural setting. Can also be propagated via root cuttings and division of suckers when dormant. Yellowhorn can take quite a while to become established.

Maintenance:
Minimal. Removal of suckers if desired.

Concerns:
None.

 

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Photo References:

http://forums2.gardenweb.com/forums/load/trees/msg1212170322566.html

http://www.arthurleej.com/p-o-m-Oct09.html

http://arnoldia.arboretum.harvard.edu/pdf/articles/2000-60-3-new-or-little-known-plants-xanthoceras-sorbifolia-1893.pdf

http://ideas.repec.org/a/ags/asagre/133111.html

 

 

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