I've developed a reputation at work for being a blood orange fanatic (“the taste of this one has a hint of rose petal” or “mmm... blackberry”), so I'm sure it will surprise everyone at UBC BG that I opted to photograph a Cara Cara navel orange for today's BPotD. There is a reason, though; the blood oranges available in local markets are the cultivar 'Moro'. Moro blood oranges can vary in colour inside from orange to purplish-red, while Cara Cara navel oranges, I've found, are quite consistent in the pinkish-orange colour of their flesh. I chose consistency over the risk of slicing open a number of blood oranges to find the right one. Cara Cara navel oranges are my second favourite orange, so that's why I had both in the kitchen.
Citrus sinensis 'Cara Cara' was discovered in 1976 as a mutation of a Washington navel orange in Valencia, Venezuela. The Citrus Variety Collection at the University of California, Riverside, shares both photographs and an explanation of the pinkish colour on its web page for sweet oranges; note that this page is an excellent resource for comparing orange varieties! UC Riverside also provides the book “The Citrus Industry” online, so if you're interested in either the botany of Citrus or the horticultural varieties of Citrus, you should find what you're looking for in those pages.
A few recipes, if you're so inclined (though I doubt any will beat the blood orange sorbet I had last week): Cara Cara orange & vanilla sorbet (discovered via Lamb Martini weblog) and frozen soufléed oranges from Greg Atkinson for The Seattle Times.
Lastly, for those wondering about the Valentine's Day significance of oranges: somewhere along the way, I've read that ingesting food is one of the most intimate acts. Minutes after these photographs were taken, I ate the sliced orange in a torrid act of love.