Q: I bought a Persian lime tree and the root stock took over. Now we have the yellow oranges with a rough skin that are the best lemons we ever tasted. We would like to buy some more and we don't know what to call them. Can you help?
A: If your sour orange rootstock has taken over, that is the fruit you are now getting. The good news is, sour orange trees can volunteer readily from self-sown seeds. The bad news is, I can't tell you the name of your particular sour orange. There are several groups of sour oranges, and within those groups there are certain cultivars.
These are the groups:
Normal group (large, seedy fruits)
Cultivars include African, Brazilian, Rubidoux, Standard, Oklawaha and Trabut. Oklawaha originated in the United States; it has large fruits rich in pectin and is prized for marmalade.
Cultivars include Daidai or Taitai, which are popular in Japan and China. The fruits are large with a very thick peel, very acid pulp and many seeds. The tree is somewhat dwarf and almost thornless. It's prized for its flower buds, which are dried and mixed with tea for their scent.
Goleta has medium-large fruits with juicy, medium-sour pulp and very few seeds. The tree is medium sized and almost thornless.
Bouquet has small, deep-orange acidic fruits with few seeds. The tree is less than 10 feet tall and is grown as an ornamental. Bouquet was grown specifically as rootstock for citrus in California and Florida, so there's a possibility that's is what you have.
This is includes any sweet-acid forms of the sour orange introduced by Spaniards and formerly found growing in the Indian River region of Florida. These oranges are often seen in a naturalized state in the West Indies. The peel is orange-red and the pulp is darker than that of the normal sour orange.
You should contact some nurseries in your area that either sell citrus or can lead you to citrus nurseries that sell retail. They may be able to help you find a close match for your sour orange.