Citrus halimii is a citrus tree and fruit, belonging to the papeda subgroup of citrus

Citrus

Citrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...

 plants. It was first discovered and catalogued in 1973.

Distribution

Citrus halimii is quite rare and poorly studied. After its initial 1973 discovery and description, it has only been observed in a handful of locations scattered across Southeast Asia

Southeast Asia

Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

: Thailand

Thailand

Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

 and Malaysia (the locations of the first discoveries), along with isolated stands in Indonesia

Indonesia

Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

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Description

Citrus halimii is a midsized evergreen

Evergreen

In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...

 tree, with a mature height of 20 to 25 feet; it is somewhat less thorny than other citrus. Like other members of the papeda sub-group, the halimii has relatively large leaves, with a long, winged petiole

Petiole (botany)

In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...

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The fruits of C. halimii are edible, but sour. They are round and small, measuring about 5–7 cm in diameter. The rather thick rind eventually ripens to yellow or orange-yellow; internally the rind is tightly bound to the flesh. The yellow-green segments are filled with a number of large seeds, and a small quantity of juice.