Richard

Species of Fortunella and some of the hybrids are definitely hardier than most Citrus species.

Many folks on this site grow oval or Nagami Kumquat (Fortunella margarita). It has a sweet tasting rind and sprite, tangy fruit. The fruit is typically eaten whole. Fruits are typically 1.25" to 1.5" long and about 0.75" wide. The rind is thick in comparison to the size of the fruit -- but it is also the main taste feature. The plants are smaller in stature than Citrus, so I grow all of mine on standard rootstock -- I see no reason for dwarfing rootstock even in a pot.

The Hong Kong Kumquat (aka round kumquat or golden-bean kumquat) is Fortunella hindsii. The fruit size is about the same length or slightly smaller than F. margarita. The skin of the fruit is not as sweet as F. margarita, and the fruit is also less flavorful -- although not unpleasant.

There are other interesting Fortunella species to discuss later, but for now I thought it worth mentioning these hybrids:

Calamondin (aka Calamansi in the Philippines) is a natural and also human-replicated hybrid of Hong Kong Kumquat x Mandarin. The fruit size is about the same as Hong Kong Kumquat. The rind is thinner than most Fortunella and a little bit less sweet. The fruit is quite sour. It is a popular ingredient in foods of the eastern hemisphere.

Mandarinquat is a hybrid of Nagami Kumquat and Mandarin. The fruits are round and larger than Nagami, about 1.5" to 1.75" in diameter. The rind is no thicker than Nagami but proportionally thinner because the fruit is larger. The rind is semi-sweet and the fruit flavor is tangy tangerine.

Looking at Olafhenny's picture of the plant in the room with the New York - London - Tokyo clocks, the fruit size appears to be larger than Fortunella species and the rind is a bit uncharacteristic as well. So perhaps it is Nagami or Meiwa Kumquat x Mandarin -- or another Fortunella unknown to western culture for all to enjoy.

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