Denise and Lindsay's Iris

Denise and Lindsay's Iris
Photo by J Hulse

Saturday, March 17, 2012




Family: Solanaceae

Genus: Solanum

Species: lycopersicum

The scientific species epithet lycopersicum means "wolf peach", and comes from German werewolf myths. These myths said that deadly nightshade was used to summon werewolves, so the tomato, a close relative, but with much larger fruit was named the "wolf peach" when it arrived in Europe.

Tomato may refer to both the plant (Solanum lycopersicum) and the fruit which it bears. It Originated in South America. The tomato fruit is consumed in many ways, including raw, as an ingredient in many dishes and sauces, and in drinks. While it is botanically a fruit, it is considered a vegetable for culinary purposes.  The fruit is rich in lycopene, which may have beneficial health effects. The plants typically grow to 3–10 feet in height and have a weak stem that often sprawls over the ground and vines over other plants.  (Staking is essential.)
Tomatoes are one of the most common garden fruits in the United States and, along with zucchini, have a reputation for outproducing the needs of the grower.  It invariably tops the lists of America’s favorite home garden crops.
The Aztecs called the fruit xitomatl (pronounced [ʃiːˈtomatɬ]), meaning plump thing with a navel. Other Mesoamerican peoples, including the Nahuas, took the name as tomatl, from which some European languages derived the name "tomato".
The definition of an heirloom tomato is vague, but unlike commercial hybrids, all are self-pollinators who have bred true for 40 years or more.

There are around 7500 tomato varieties grown for various purposes. Heirloom tomatoes are becoming increasingly popular, particularly among home gardeners and organic producers, since they tend to produce more interesting and flavorful crops at the cost of disease resistance and productivity.  Hybrid plants remain common, since they tend to be heavier producers, and sometimes combine unusual characteristics of heirloom tomatoes with the ruggedness of conventional commercial tomatoes.
Tomato varieties are roughly divided into several categories, based mostly on shape and size.
  • "Slicing" or "globe" tomatoes are the usual tomatoes of commerce, used for a wide variety of processing and fresh eating.
  • Beefsteak tomatoes are large tomatoes often used for sandwiches and similar applications. Their kidney-bean shape, thinner skin, and shorter shelf life makes commercial use impractical.
  • Oxheart tomatoes can range in size up to beefsteaks, and are shaped like large strawberries.
  • Plum tomatoes, or paste tomatoes (including pear tomatoes), are bred with a higher solids content for use in tomato sauce and paste, and are usually oblong.
  • Pear tomatoes are obviously pear-shaped, and are based upon the San Marzano types for a richer gourmet paste.
  • Cherry tomatoes are small and round, often sweet tomatoes generally eaten whole in salads.
  • Grape tomatoes, a more recent introduction, are smaller and oblong, a variation on plum tomatoes, and used in salads.
  • Campari tomatoes are also sweet and noted for their juiciness, low acidity, and lack of mealiness. They are bigger than cherry tomatoes, but are smaller than plum tomatoes.
Early tomatoes and cool-summer tomatoes bear fruit even where nights are cool, which would otherwise discourage fruit set. There are also varieties high in beta carotenes and vitamin A, hollow tomatoes and tomatoes which keep for months in storage.
Tomatoes are also commonly classified as determinate or indeterminate.  Determinate, or bush, types bear a full crop all at once and top off at a specific height; they are often good choices for container growing.  Indeterminate varieties develop into vines that never top off and continue producing until killed by frost.  As an intermediate form, there are plants sometimes known as vigorous determinate or semideterminate; these top off like determinates, but produce a second crop after the initial crop. The majority of heirloom tomatoes are indeterminate, although some determinate heirlooms exist. Tomatoes grow well with seven hours of sunlight a day. A fertilizer with an NPK (Nitrogen, Phosporous, Potassium) ratio of 5-10-10 is often sold as tomato fertilizer or vegetable fertilizer, although manure and compost are also used.

Diseases and pests
For a more comprehensive list, see List of tomato diseases. (From Wikipedia)
Tomato cultivars vary widely in their resistance to disease. Modern hybrids focus on improving disease resistance over the heirloom plants.  One common tomato disease is tobacco mosaic virus, so smoking or use of tobacco products are discouraged around tomatoes, although there is some scientific debate over whether the virus could possibly survive being burned and converted into smoke.  Various forms of mildew and blight are also common tomato afflictions, which is why tomato cultivars are often marked with a combination of letters which refer to specific disease resistance. The most common letters are: Vverticillium wilt, Ffusarium wilt strain I, FFfusarium wilt strain I and II, Nnematodes, Ttobacco mosaic virus, and Aalternaria.

Another particularly dreaded disease is curly top, carried by the beet leafhopper, which interrupts the lifecycle, ruining a nightshade plant as a crop. As the name implies, it has the symptom of making the top leaves of the plant wrinkle up and grow abnormally.
Some common tomato pests are stink bugs, cutworms, tomato hornworms and tobacco hornworms, aphids, cabbage loopers, whiteflies, tomato fruitworms, flea beetles, red spider mite, slugs,  and Colorado potato beetles.
When insects attack tomato plants, they produce the plant peptide hormone, systemin, which activates defensive mechanisms, such as the production of protease inhibitors to slow the growth of insects. The hormone was first identified in tomatoes, but similar proteins have been identified in other species since.

Companion plants
See also: List of companion plants and List of beneficial weeds    (From Wikipedia)

Tomatoes serve, or are served by, a large variety of companion plants.  In fact, one of the most famous pairings is the tomato plant and carrots, studies supporting this relationship having produced a popular book about companion planting, Carrots Love Tomatoes.

Additionally, the devastating tomato hornworm has a major predator in various parasitic wasps, whose larvae devour the hornworm, but whose adult form drinks nectar from tiny-flowered plants like umbellifers. Several species of umbellifer are therefore often grown with tomato plants, including parsleyand dill. These also attract predatory flies that attack various tomato pests.
On the other hand, borage is thought to actually repel the tomato hornworm moth.
Other plants with strong scents, like alliums (onions, chives, garlic) and mints (basil, oregano, spearmint are simply thought to mask the scent of the tomato plant, making it harder for pests to locate it, or to provide an alternative landing point, reducing the odds of the pests from attacking the correct plant. These plants may also subtly impact the flavor of tomato fruit.
Ground cover plants, including mints, also stabilize moisture loss around tomato plants and other solaneae, which come from very humid climates, and therefore may prevent moisture-related problems like blossom end rot.
Finally, tap-root plants like dandelions break up dense soil and bring nutrients from down below a tomato plant's reach, possibly benefiting their companion.
Tomato plants, on the other hand, protect asparagus from asparagus beetles, because they contain solanum that kills this pest, while asparagus plants (as well as marigolds) contain a chemical that repels root nematodes known to attack tomato plants.
In the wild, original state, tomatoes required cross-pollination; they were much more self-incompatible than domestic cultivars. As a floral device to reduce selfing, the pistil of wild tomatoes extends farther out of the flower than today's cultivars. The stamens were, and remain, entirely within the closed corolla.
This is not the same as self-pollination, despite the common claim that tomatoes do so. That tomatoes pollinate themselves poorly without outside aid is clearly shown in greenhouse situations, where pollination must be aided by artificial wind, vibration of the plants (one brand of vibrator is a wand called an "electric bee" that is used manually), or more often today, by cultured bumblebees.[citation needed] The anther of a tomato flower is shaped like a hollow tube, with the pollen produced within the structure, rather than on the surface, as in most species. The pollen moves through pores in the anther, but very little pollen is shed without some kind of outside motion. The best source of outside motion is a sonicating bee, such as a bumblebee, or the original wild halictid pollinator. In an outside setting, wind or animals provide sufficient motion to produce commercially viable crops.
Hydroponic and greenhouse cultivation
Tomatoes are often grown in greenhouses in cooler climates, and there are cultivars such as the British 'Moneymaker' and a number of cultivars grown in Siberia that are specifically bred for indoor growing. In more temperate climates, it is not uncommon to start seeds in greenhouses during the late winter for future transplant.
Hydroponic tomatoes are also available, and the technique is often used in hostile growing environments, as well as high-density plantings.

Picking and ripening
Unripe tomatoes
Tomatoes are often picked unripe (and thus colored green) and ripened in storage with ethylene. Unripe tomatoes are firm. As they ripen they soften until reaching the ripe state where they are red or orange in color and slightly soft to the touch.  Ethylene is a hydrocarbon gas produced by many fruits that acts as the molecular cue to begin the ripening process. Tomatoes ripened in this way tend to keep longer, but have poorer flavor and a mealier, starchier texture than tomatoes ripened on the plant.  They may be recognized by their color, which is more pink or orange than the other ripe tomatoes' deep red, depending on variety.
Recently, stores have begun selling "tomatoes on the vine", which are determinate varieties that are ripened or harvested with the fruits still connected to a piece of vine. These tend to have more flavor than artificially ripened tomatoes (at a price premium).
At home, fully ripe tomatoes can be stored in the refrigerator, but are best kept at room temperature. Tomatoes stored cold will still be edible, but tend to lose flavor; thus, "Never Refrigerate" stickers are sometimes placed on tomatoes in supermarkets.

Tomatoes are now eaten freely throughout the world, and their consumption is believed to benefit the heart, among other organs. They contain the carotene lycopene, one of the most powerful natural antioxidants. In some studies, lycopene, especially in cooked tomatoes, has been found to help prevent prostate cancer, but other research contradicts this claim.   Lycopene has also been shown to improve the skin's ability to protect against harmful UV rays.  Natural genetic variation in tomatoes and their wild relatives has given a genetic plethora of genes that produce lycopene, carotene, anthocyanin, and other antioxidants. Tomato varieties are available with double the normal vitamin C (Doublerich), 40 times normal vitamin A (97L97), high levels of anthocyanin (resulting in blue tomatoes), and two to four times the normal amount of lycopene (numerous available cultivars with the high crimson gene).

Medicinal properties
Lycopene has also been shown to protect against oxidative damage in many epidemiological and experimental studies. In addition to its antioxidant activity, other metabolic effects of lycopene have also been demonstrated. The richest source of lycopene in the diet is tomato and tomato derived products.  Tomato consumption has been associated with decreased risk of breast cancer,  head and neck cancers  and might be strongly protective against neurodegenerative diseases. Tomatoes and tomato sauces and puree are said to help lower urinary tract symptoms (BPH) and may have anticancer properties.

Tomatoes that are not yet ripe are optimally stored at room temperature uncovered, out of direct sunlight, until ripe. In this environment, they have a shelf life of three to four days. When ripe, they should be used in one to two days. Tomatoes should only be refrigerated when well ripened, but this will affect flavor.

Plant toxicity
Like many other nightshades, tomato leaves and stems contain atropine and other tropane alkaloids that are toxic if ingested. Ripened fruit does not contain these compounds.  Leaves, stems, and green unripe fruit of the tomato plant contain small amounts of the poisonous alkaloid tomatine.  Use of tomato leaves in tea (tisane) has been responsible for at least one death.   However, levels of tomatine are generally too small to be dangerous.
Tomato plants can be toxic to dogs if they eat large amounts of the fruit, or chew plant material.
Tomato plants are vines, initially decumbent, typically growing six feet or more above the ground if supported, although erect bush varieties have been bred, generally three feet tall or shorter. Indeterminate types are "tender" perennials, dying annually in temperate climates (they are originally native to tropical highlands), although they can live up to three years in a greenhouse in some cases. Determinate types are annual in all climates.

Tomato fruit is classified as a berry. As a true fruit, it develops from the ovary of the plant after fertilization, its flesh comprising the pericarp walls. The fruit contains hollow spaces full of seeds and moisture, called locular cavities. These vary, among cultivated species, according to type. Some smaller varieties have two cavities, globe-shaped varieties typically have three to five, beefsteak tomatoes have a great number of smaller cavities, while paste tomatoes have very few, very small cavities.
For propagation, the seeds need to come from a mature fruit, and be dried or fermented before germination.

The pronunciation of tomato differs in different English-speaking countries; the two most common variants are /təˈmɑːtoʊ/ and /təˈmeɪtoʊ/. Speakers from the British Isles, most of the Commonwealth, and speakers of Southern American English typically say /təˈmɑːtoʊ/, while most North American speakers usually say /təˈmeɪtoʊ/.
The word's dual pronunciations were immortalized in Ira and George Gershwin's 1937 song Let's Call the Whole Thing Off ("You like /pəˈteɪtoʊ/ and I like /pəˈtɑːtoʊ/ / You like /təˈmeɪtoʊ/ and I like /təˈmɑːtoʊ/") and have become a symbol for nitpicking pronunciation disputes. In this capacity, it has even become an American and British slang term: saying /təˈmeɪtoʊ, təˈmɑːtoʊ/ when presented with two choices can mean "What's the difference?" or "It's all the same to me."