I begin to wonder what these wee Christmas oranges are, exactly. These days I often see clementines at my grocer's, and I'm not sure if they're the same as the mandarins of my youth, nor how each relates to tangerines and navel oranges and all of that ilk.
So a bit of poking around gets me confused. An alternate name for the mandarin orange is the tangerine, but a source informs me that "in the trade" that name is usually restricted to orange-skinned varieties of mandarins with thick, rough skins and sweet flesh. (Tangerines were named after Tangier, and indeed Morocco is still a major producer of mandarins, though they originated in Asia, which explains the mandarin moniker.) One source tells me that mandarins are "treated as" members of a separate orange species, Citrus reticulata, but the wording is obfuscatory: are they really a separate species, or aren't they? Another source avers that mandarins are a category of oranges with loose skins, sometimes called kid glove oranges. (Kind of makes them sound like old ladies who smell of lavender but were once real classy, doesn't it?) Turns out this group or category or species or faux-species or whatever it is is a motley crew, ranging in size from "small as an egg" to "large as a grapefruit", with sweet and sour varieties, some seedless, some seedy; only their loose skins unite them. That, and the fact that their segments separate easily.
Besides the thick-skinned tangerines, there's also little sweet mandarins, often called clementines, with thin peels and no seeds, and the similar dancy oranges, which have seeds. Satsuma oranges are Japanese and seedless, and are the ones which are usually confined to canny coffins. These are the most common types, but like most citrus fruits, mandarins hybridize freely, so there's lots more varieties already, and more being developed every year.
There are two recipes at the moment here on e2 that obviously contain mandarin oranges: Mandarin Orange Jell-O Salad and Chicken with Mandarin Oranges and Almonds. Forgive me dear friends if I look askance at these two recipes, for they incorporated canned mandarin oranges. My motto is always: use fresh if you can. But what do I know; I've never made either. Not likely to either, with those canned oranges. :-P