(See also: Citrus taxonomy § Fortunella & Citrofortunella) Kumquats (or cumquats in Australian English; UK /ˈkʌmkwɒt/; US /ˈkʌmˌkwɑːt/ or /ˈkʌmkwɔːt/) are a group of small fruit-bearing trees in the flowering plant family Rutaceae, either forming the genus Fortunella, or placed within Citrus sensu lato. The edible fruit closely resembles that of the orange (Citrus sinensis), but it is much smaller, being approximately the size and shape of a large olive. Kumquat is a fairly cold-hardy citrus.