Naval orange?

Perhaps yesterday's blog about scurvy subtly influenced someone to ask about the naval orange.  Of course, it was the use of lime juice to prevent scurvy in the British navy that resulted in the nickname "limey".  However this isn't a naval

nickname at all, it's navel.  Yes, an orange with a belly button.  If you slice a navel orange in half top to bottom you'll see that it's really two oranges, a large one almost surrounding a small one at the apex of the fruit, and the slight protrusion of this 2nd small fruit through the rind of the larger fruit produces the navel (bottom of image) on the apex of the fruit.  [Image courtesy of Brandizzi, Wikimedia Creative Commons] This type of orange has probably arisen more than once, or if just once, this sport, this mutant showed up 200-400 years ago.  In addition to having this double ovary, one on top of the other, the mutation rendered the fruit sterile so it produces no seeds.  Good for the eater, bad for the plant.  Navel oranges can only be reproduced asexually by cuttings or buds grafted onto other root stock.  So no navy involved, and no umbilical scar either really, but let's be careful with those vowels people.  Oh, and this is a fun fact too.  The flesh you eat in citrus fruits is not derived from the ovary wall; the juice sacs are modified hairs (look at one carefully) that fill the locule, the space, around the seeds, if the fruit has any. 

What is a nectarine?

Someone asked an interesting question, "What is a nectarine?"  A nectarine is a fuzzless peach, no more, no

less, a peach with a smooth skin.  Although considered a different fruit and a variety of peach (same species), the genetic difference is trivial.  A dominant gene produces the fuzzy hairs on a peach, and if only recessive genes are present, the skin is smooth.  Whether the nectarine is redder or just looks redder skinned when hairless is hard to determine, but the nectarine is not the result of hybridization with a plum although both are in the same genus, Prunus.  The fuzzless condition probably arose via a mutation in a bud resulting in a branch bearing fuzzless peaches, a so-called "sport".  Sports arise fairly often because plants sequester germ tissue from somatic tissue annually in a woody perennial.  Taking buds and grafting them to peach root stock propagates the mutation.  The nectarine mutation has probably occurred several times arising from several different peaches and they show the same range of general diversity: white or orange flesh, cling or free-stone.  However, in TPP's experience, nectarines never taste as good as a peach, and it may be because peaches arrive in farmer's markets fresh, directly from the orchard, but in our locale nectarines never do, so the nectraines in markets are probably picked under ripe to reduce bruising damage and they then do not ripen to full flavor.  Nectarines tend to be smaller and sweeter, often with white flesh, perhaps again reflecting whatever peach variety they arose from.  Image courtesy of Flagstaffotos.