Ichang papeda - Citrus ichangensis

Scientific classification

Kingdom:        Plantae

(unranked):     Angiosperms

(unranked):     Eudicots

(unranked):     Rosids

Order: Sapindales

Family:            Rutaceae

Genus: Citrus

Species:           C. ichangensis

Binomial name           Citrus ichangensis

Swingle

Citrus ichangensis, the Ichang papeda (Chinese: 宜昌橙), is a slow-growing species of the Citrus subg. Papeda, which has characteristic lemon-scented foliage and flowers.

It is native to southwestern and west-central China and is likely named for the city of Yichang (宜昌), in China's Hubei province. It is sometimes referred to as Citrus × ichangensis.

The Ichang papeda's main claim to fame is its unusual hardiness. With the exception of Poncirus trifoliata, it is the hardiest citrus plant, tolerating both moderate frost and damp conditions.

For this reason, it is perhaps the only species of true citrus which can be reliably grown outside in the temperate areas of Europe and the United States.

Relatively rare in cultivation, the Ichang papeda is a large shrub or small tree, growing to 3-4.5 m, and produces a small, mandarin-like fruit. Leaves feature a broad petiole, and resemble the leaves of the yuzu and the Kaffir lime in appearance.

The fruit has a fragrant, but rugged rind, and may be oval, spherical, or flattened in shape, ripening to yellow or orange. The fruit contains many large monoembryonic seeds and a small quantity of bitter or sour juice; some fruits lack juice entirely and are instead filled with a mass of pith and seeds.

The Ichang papeda is occasionally grown as an ornamental.

Hybrids

Ichang lemon (also known as the shangjuan)

Yuzu

Kabosu

Hyuganatsu

Both the shangjuan and the yuzu have a number of culinary uses and are notably cold-hardy.

Ichang papeda

Citrus ichangensis

Parentage/origins: Parents unknown. From China.

Rootstocks of accession: Yuma Ponderosa lemon.

Season of ripeness at Riverside: Unknown at this time.

Notes and observations:

11/13/1989, EMN:First fruit here, good crop. Larger & seedier fruit than other C. ichang accessions. Seems to be true C. ichangensis.

11/29/2007, DK & TS: Round orange fruit, unlike the other selections in the CVC. Fruit is seedy and bland.

Description from The Citrus Industry Vol. 1 (1967):

A spiny shrub or small tree usually 5-15 ft. [1.5-4.6 m] high; twigs angular when young, with stout, sharp spines, 1.5-2.5 cm long, often reduced or lacking on flowering twigs; leaves narrow, 4-6 times longer than wide, mostly 8-11.5 X 1.8-3 cm; petioles very large, broadly winged, obovate or oblong-spatulate, evenly rounded at the tip and narrowed abruptly at the base, usually 3.5-6 X 2-3 cm; leaf blade ovate-acuminate, often more or less caudate, emarginate at the tip and evenly rounded or bluntly pointed at the base, usually 3-6 X 1.8-3 cm, often not equaling the winged petiole in area; flowers 2.5-3 cm diam., 5-merous; sepals thick, 3 mm long and 3 mm wide, with minutely ciliate margins; petals oblong, 1.5-2 X 0.5-0.8 cm, white; stamens 20, at first all connate to the tips, finally breaking up into several bundles, about 10 mm long; pistil about 10 mm long; style very short, caducous; stigma nearly as large as the ovary; ovary with 7-9 locules, ovules numerous in each locule; fruits small, glabrous, 3-4 cm diam. in dried specimens (probably 3.5-5 cm when fresh), peel rough, 2-4 mm thick in dried specimens; seeds large, very thick, 12-18 X 12-18 X 7-9 mm in dried material, very blunt at both ends, with a chalazal cap about 12 X 5 mm, apparently monoembryonic.

This species differs from its congeners in having large, very thick seeds and slender leaves 4-6 times longer than broad, with very large, winged petioles often as large or larger than the blade.   It differs from C. hystrix in having oblong, rather than triangular, winged petioles and much larger flowers with connate stamens.

This remarkable plant, which grows in a truly wild state in central and southwestern China, is doubtless the most cold resistant of all the evergreen species in the orange subfamily. It differs greatly from the other species in the subgenus Papeda in having large flowers, partly connate stamens, and large, very thick seeds, which are nevertheless monoembryonic.

The leaves also differ from those of all other species of Papeda in having extremely long but rather narrow winged petioles, often exceeding in area the slender, pointed, lanceolate leaf blades.

In 1926, Swingle brought to this country a healthy young seedling of this plant from Hupeh Province, grown for him at Nanking, China, by C. C. Hu. As C. ichangensis is the hardiest known evergreen species of Citrus, it is of great interest for use in breeding cold-resistant hybrids, such as the Ichang lemon and Yuzu."