An heirloom tomato (also called heritage tomato in the UK) is an open-pollinated, non-hybrid heirloom cultivar of tomato. They are classified as family heirlooms, commercial heirlooms, mystery heirlooms, or created heirlooms. They usually have a shorter shelf life and are less disease resistant than hybrids. They are grown for various reasons: for food, historical interest, access to wider varieties, and by people who wish to save seeds from year to year, as well as for their taste. Taste Many heirloom tomatoes are sweeter and lack a genetic mutation that gives tomatoes a uniform red color at the cost of the fruit's taste. Varieties bearing that mutation which have been favored by industry since the 1940sthat is, tomatoes which are not heirloomsfeature fruits with lower levels of carotenoids and a decreased ability to make sugar within the fruit. Cultivars Heirloom tomato cultivars can be found in a wide variety of colors, shapes, flavors, and sizes. Some heirloom cultivars can be prone to cracking or lack disease resistance. As with most garden plants, cultivars can be acclimated over several gardening seasons to thrive in a geographical location through careful selection and seed saving. Some of the most famous examples include Aunt Ruby's German Green, Banana Legs, Big Rainbow, Black Krim, Brandywine, Cherokee Purple, Chocolate Cherry, Costoluto Genovese, Garden Peach, Gardener's Delight, Green Zebra, Hawaiian Pineapple, Hillbilly, Lollypop, Marglobe, Matt's Wild Cherry, Mortgage Lifter, Mr. Stripey, Neville Tomatoes, Paul Robeson, Pruden's Purple, Red Currant, San Marzano, Silvery Fir Tree, Three Sisters, and Yellow Pear. Seed collecting Heirloom seeds "breed true," unlike the seeds of hybridized plants. Both sides of the DNA in an heirloom variety come from a common stable cultivar. Heirloom tomato varieties are open pollinating, so cross-pollination can occur. Generally, tomatoes most likely to cross are those with potato leaves, double flowers (found on beefsteak types), or currant tomatoes. All of these should be kept at least apart. All other tomatoes should be kept at least apart to reduce the possibility of cross-pollination. Seed should be saved from tomatoes picked from several different plants throughout the growing season that are true to type to preserve genetic diversity. These seeds should be mixed at the end of the growing season. There are two main ways to save heirloom tomato seeds. The first method is to let the tomato ripen completely, even to the point of beginning to rot, and then remove the