trifoliate orange

species: Poncirus trifoliata

common name: trifoliate orange, Chinese bitter orange

family: Rutaceae

where & when encontered: Greenfield, CA - 2011; Old Westbury, NY

This is an interesting case. I encountered this distinctive citrus tree independently on the east and west coasts, not realizing they were the same plant. It is the most northern-growing citrus that I am aware of; it tolerates cold better than most citrus, which is how it survives in New York. The fruit is bitter, containing the chemical poncirin, but can be used to make marmalade.