Citrus halimii
Citrus halimii, or mountain citron, is a citrus with sour fruit. Historically placed within the polyphyletic grouping of papedas, it has since been determined to be a wild species most closely related to the kumquats, and is not related to the true citron. 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 been observed in only a handful of locations scattered across Southeast Asia: Thailand and Malaysia, along with isolated stands in Indonesia.Description
Citrus halimii is a midsized evergreen tree, with a mature height of ; it is somewhat less thorny than other citrus. Like other papedas, the halimii has relatively large leaves, with a long, winged petiole.The fruits of C. halimii are edible, but sour. They are round and small, measuring about 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.