Stone fruits have one hard pit in their centres, rather than numerous seeds. They are primarily summer fruits, and California is the largest stone fruit harvester in the United States. In off season, stone fruit can be imported from warmer climates. There are a few different types of stone fruit, with many variations of each.
Plums are juicier than other stone fruits and have a tart skin. They can be dark purple, red, yellow or green. European plums have a narrower, oblong shape and are often used for making prunes, which are dried plums.
Nectarines look like a peach without the fuzzy skin. They are sweeter than peaches, and are more nutritious. They are hard to grow on trees because of their susceptibility to harsh weather, so harvesters often pick them too soon. When buying, be careful of the colour and firmness. Nectarines with green spots or that are very hard were picked too soon and won't taste sweet.
There are two major types of peaches, white and yellow. The yellow peach has a dark yellow skin, mixed with red and pink. The flesh is bright yellow. The white peach has a pale yellow flesh and its skin is a paler yellow with red and pink. White peaches ripen faster and are less tart.
Cherries come in different varieties. Bing cherries are heart-shaped and dark red, and Lambert cherries are very similar in colour and sweetness. Chokecherries are best for jams and aren't for eating raw because they are incredibly tart. Pale cherries tend to be sweeter and darker cherries tend to be tart.
The common avocado is the Hass avocado, which can be grown all year round. It's oval in shape and has a rough, purplish-black skin, with a bright green flesh. Avocados are high in potassium and iron.
Apricots are the sweetest stone fruit, and are very susceptible to weather. Because of this they are often picked before they are completely ripe, and should be allowed to soften a few days at home before eating.
Hybrid fruits are a cross breed of at least two fruits that take certain aspects of one fruit and combine it with another. The pluot or plumcot is a cross between a plum and apricot, where the plum is the dominating fruit. The aprium is a cross between a plum and apricot, where the apricot is dominating.