How does a SPORT develop? Does it spring up beneath the parent tree?
OR, Is it an apparent offspring of the parent until such time as the fruit develops and a change is noticed in the color or flavor?

Thanks

Bill

It doesn't spring up beneath the parent tree!
A sport is a bud that develops into a branch that has different characteristics from the rest of the tree. It may be insignificant, or nothing to do with the fruit produced on that limb. For instance, the leaves may be a slightly different size or shape or colour. However, sports are usually noticed when the fruit is different. Size, flavour, colour, or time of maturity perhaps. If someone observes these differences and considers them useful or interesting then they may be propagated as a new variety. Many sports, however, are less desirable than the original variety.

Sports mutation can also develop from nucellar embryos. Some nucellar seeds can be irradiated, subject to other stresses or chemical exposures and other DNA modification stresses and the resulting plant would have slightly different characteristics. The plant breeders would then pore through and select the best. The Tango mandarin was developed by irradiating the seeds of W.Murcott, and the final selection has a major natural defect called seedlessness, which is a major trait for us that is desired.

the most common is of course the bud mutations. The Red Smith for example, was from a branch that bore red fleshed fruits. Then they selected seeds from the reddest fleshed fruits and planted them, and from the tree that bore the reddest fleshed fruit, they took budwoods of that.

As I understand it sports/mutations are a radical genetic change occurring when the chemical structure of GENES is permanently reorganized. The sun's ultraviolet light is believed to be one of several, natural mutagenic agents. Most mutations are thought to be lethal. But those that seem to enhance the plants survival and have been transmitted in the gene pools of plants (and animals) have profoundly influenced the course of evolution., especially when, through natural selection, they conferred greater adaptive capacities upon their recipients. Both mutations and the outcome of natural hybridizations are among several random events taking place at a chromosomal level. Just by their randomness it points to the IMPORTANT fact that evolution is not a directed process, as it does not work towards predetermined goals. Although the process of mutation/sport is impossible to comprehend in totality or entirety,, the splendid realm of the earth's vegetation wrought by nature by the process of mutation/sport processes is everywhere to be seen if one looks around. - Millet

Thanks to all for answering my question. I`ve read so much about a particular variety being a `sport` of some other variety that I wondered
how a sport developed.

Bill

Billy, a good example is the Cara Cara orange. A grower in Venezuela had a grove of Washington Navel orange trees.. One day while walking through his grove, he noticed a branch on one of his Washington Navel trees had started to grow pink colored "Washington Navels", while the balance of that tree still produced regular Washington Navels. He named the new sport Cara Cara after a large bird native to his area. All the Cara Cara trees in the world, came from that one branch. - Millet

In the world of other plants I am familiar with, sports are often reversible. Does this happen in citrus?

An example I know of is African Violets-- many bicolored varieties are sports of a solid color and sometimes the bicolored variety will go back to soild.

There are close to 400,000 recognizably different kinds of plants, called species, in the world today. So diverse are their forms that it is not easy to write an all inclusive definition of the word "plant." One third of all plants do not have roots, stems or leaves as we know these parts. About 150,000 plant species never produce flowers, and almost that same number do not grow from seeds. It is this kind of diversity and amazing variety of shapes, colors and lifestyles that continually excite our interest in these organisms called plants. - Millet