Biological Diversity 2003   

Photos Courtesy of
and Floridata

Kingdom: Plantae
Phylum: Anthophyta/Tracheophyta
Class: Magnoliopsida
Order: Solanales
Family: Solanaceae
Genus: Solanum
Species: lycopersicum (this is the common garden tomato. There are several other species in the genus, including cherry and pear tomatoes)

Currant tomatoes...another cool species!

Photo Courtesy of

What's up with Lycopene??
You may have noticed that recently there has been a lot of buzz about a mysterious antioxidant called lycopene. Found almost exclusively in tomatoes, lycopene became famous in 1995 when a Harvard study found that this carotenoid (which is responsible for the vibrant red of many tomato varieties) protected against cancer. Continuing studies seem to be supporting these findings, and expanding on them with experiments indicating that lycopenes are more easily absorbed from cooked tomatoes and tomatoes prepared with fats (Florida Tomato Committee). Since then, the world has gone lycopene crazy, and everything from lycopene tablets to powdered supplements are available. And to think, several years ago they thought it was useless.

How about those Heirlooms?
You’ve probably heard of heirloom tomatoes, but have you ever wondered what they are or where exactly they come from? Well, here’s the lowdown: because tomato plants are naturally self-pollinating, they have the general tendency to become genetically homozygous after many generations. Early tomato cultivars would thus remain virtually the same over many years, eventually earning the name heirloom from the community that kept them. Heirloom cultivars dating back hundreds of years can still be found growing today, especially throughout Eastern Europe.
Because of their colorful backgrounds, heirlooms often have rich histories, many of which are reflected in their names. Jeff Davis is an old cultivar from Alabama named after the Confederate president, a cultivar found growing at Edgar Allen Poe’s estate is named Hopkins in honor of his mother, and Broad Ripple Yellow Currant (pictured below) was found growing out of a sidewalk crack in Indianapolis in 1984 (Cox 2000).
Some tantalizing heirlooms

Photo Courtesy of


Conservation Organizations:
The Places to BE

National Wildlife Federation -- This nationally based conservation association has consistently struggled to educate both growers and consumers about the environmental dangers posed by pesticide and fungicide use.

Natural Resources Defense Council -- Another national conservation organization that works to ensure a healthy environment for all living organisms. They have been pushing for stricter regulation of pesticides used in farming and the expansion of organic farming programs.

CropLife America -- A group that promotes the environmentally sound manufacturing, distribution, and use of crop protection chemicals. Its aims are to allow for safe, affordable, abundant food in a way that protects the interests of farmers, consumers, and the environment.

Association of Natural Biocontrol Producers
An organization that represents the biological pest management industry. This type of pest management utilizes beneficial insects, mites and nematodes to manage agricultural pests.


Some Snazzy Facts to Buffen up your Cocktail Party Arsenal!!
-- Tomatoes are currently the most consumed "vegetable" in America other than potatoes (Peet 2001)
-- Tomatoes are the number one contribution to diet in the United States, not because they’re particularly healthy, but simply because of the amount of them consumed (Peet 2001).
-- In 1992, Americans consumed 73.3 pounds of processed and 14.4 pounds of fresh tomatoes per person per year. (Peet 2001) By 1995, it had increased to 18.8 pounds of fresh tomatoes per person per year (Cox 2000).
-- The first salsa recipe appears to have been concocted by the ancient Aztecs, who enjoyed a snack that combined peppers, salt, and tomatoes. (Cox 2000)
-- The gelatinous coating around many tomato seeds contains chemicals that prevent the seeds from germinating within the tomato. In order for the seeds to germinate, the outer layering must be literally rotted away (Floridata 2000).
-- Potatoes are so closely related to tomatoes that they can be grafted onto one another. That means it’s possible to create a plant that produces both potatoes and tomatoes simultaneously!! (Floridata 2000)

Delicious or Deadly?

Photo Courtesy of

This may look like a friendly tomato, but it's actually a deadly nightshade plant. It makes it easier to understand why Europeans refused to eat tomatoes for almost 300 years, fearing that they were poisonous.


Tantalizing Tomatoes!!

An Introduction
Habitat & Distribution
Tomatoes originated in the Andes region of Peru, where the greatest number of wild speciescan be found today. Currently, wild tomatoes only grow in South America, where 8 species range from the Northern tip of Chile to Ecuador, including the Galapagos Islands (Cox 2000).
The tomato was first domesticated in Central America as early as 700 C.E. (California Tomato Comission), and now there are over 1,100 cultivated varieties in the species lycopersicum alone
(Dave's Garden 2003). Tomatoes can be grown in both temperate and tropical zones, as shown by the top 5 tomato producing countries: the United States, China, Turkey, Italy and India (in that order) (Cox 2000). Within the United States, the top growing states are California, Florida and Georgia, although tomatoes are grown almost everywhere.

Image Courtesy of USDA
Counter to public belief that they are a hardy plant, tomatoes are extremely sensitive to low light and adverse temperatures.
Light: Cultivated tomato plants need at least 6 hours of direct sunlight each day in order to flower.
Temperature: Tomato plants cannot grow healthy fruit if temperatures drop below 50 degrees or rise above 90 during the day and 70 at night. This accounts for the fact that, other than those grown in greenhouses, all tomatoes consumed in the U.S. between November and May come from either Florida or Mexico (Peet 2001).

Physical Characteristics

* “Wild” tomatoes (not of the same species as the common garden tomato) have tiny fruits with thin outer skins, very little flesh, and a lot of seeds. They are incapable of tolerating frost, and grow as annuals in the colder regions while in warmer regions they are perennials (Cox 2000 and Schuchert)
Tomato fruits can be yellow, orange, pink, red, white, purple or black. Their shape can vary from round to pepper-like, and they can range from cherry-size to over 2 pounds...that's a pretty big berry!!
Two examples of the awesome diversity of tomatoes:

Photos Courtesy of
* Compositionally, most of the weight of a tomato is water…solids constitute only 5%. These solids are cell walls, sugars (about half of the dry mass), and acids(about one eighth). It is the ratio of the sugars to the acids that determines the flavor, although it is usually the tomatoes with high sugar and acid contents that are considered the most flavorful (Peet 2001). In general, white and yellow tomatoes tend to be the least acidic (Floridata 2000).
* A tomato's internal makeup can vary from having two divisions in the ovary (locules) to being larger and multi-locular. With cultivated tomatoes, the number of locules has often been selected for depending upon the purpose of the tomato. Most processed tomatoes, including plum and pear varieties, have 2 locules, while fresh market tomatoes are often multi-locular, providing more chewable flesh (Peet 2001).

The tomato's reproductive habits are consistent with the general angiosperm life cycle.
All tomatoes, both cultivated and wild are naturally self-pollinating (Cox 2000).

A close-up of a cultivated tomato flower

Photo Courtesy of the Institute for Systematic Botany

Development & Lifespan

* Wild and cultivated tomatoes can be either annuals or short-lived perrenials, depending upon the environmental conditions and how they are cropped. In the wild, they have more of a tendency to operate as perennials (USDA 2002).
* There are 2 major types of tomato growth: determinate and indeterminate. Determinate growth produces "bush" tomatoes...individuals which are bred for compactness. The entire plant stops growing once the terminal fruit ripens, the remainder of the fruit all ripen simultaneously, and then the plant dies. Indeterminate growth produces tomatoes that can grow up to 10 feet in height (so-called "vining" tomatoes) and will only stop growing when killed by frost. Their fruit ripen rotationally (GardenWeb).

Conservation: A Pest Affair

Conservation Status

As a group, tomatoes are far from endangered, thus they do not appear on the United States Endangered Species Act list, the IUCN list, or the CITES list.

Conservation Issues

Tomatoes are particularly susceptible to fungal and insect infestation, thus many tomato growers resort to the use of herbicides and pesticides to prevent negative economic consequences from crop loss. The use of these chemicals, however, often has unanticipated consequences. For example, insecticides often kill insect species that control weed populations, and fungicides can kill the microorganisms that are natural predators of crop-harming nematodes. Also, by lowering earthworm populations, pest control chemicals can unintentionally affect soil fertility and water infiltration (Peet 2001).

One of the simplest ways to reduce pests is via crop rotation. If organized correctly, crop rotation can result not only pest suppression, but also an increased ability in plants to overcome pest damage. This is because well-orchestrated crop rotation can create more fertile, aerated soil. In general, diversifying rotated crops by planting species from different families is better for the integrity of the soil and the plants themselves. There is also the potential to control insect populations with natural botanical and pheromones (Peet 2001).

The tomato industry itself claims to be improving in the areas of pesticide and fungicide use. A publicity site claims that many tomatoes today are virtually free of any chemical residue, as pesticide use has been greatly reduced due to pest and disease resistant tomato cultivars, Integrated Pest Management techniques, and drip irrigation. They also state that crop management techniques are constantly improving both the taste and the color of purchaseable tomatoes(California Tomato Commission).

Not everyone agrees. Not only do the pesticides and chemicals used to create the “perfect” tomato pose an environmental hazard, many people feel that the product itself is inferior. Many small-based vegetable gardeners feel that the extents that producers have gone to in order to make tomatoes redder, smoother, and more shippable have taken away all of their flavor. A home gardening website bemoans the fact that “today’s commercial tomatoes are mealy, insipid, odorless, and tasteless replicas of real tomatoes.” (Floridata 2000)

Another concern that is often expressed is the use of ethylene spray to induce shipped tomatoes to ripen. Several groups decry the use of these chemicals, claiming that they allow the producers to produce inferior tomatoes (as they are allowed to be picked before ripening) and cover the fruits yet more chemicals. Tomato growers, on the other hand, admit that they do often spray their tomatoes, but remind people that ethylene is the plant's natural ripening hormone (Floridata 2000 and California Tomato Commission).

Some good ol' Home-grown Pesticide-Free Yellow Determinate lycopersicum

Photo Courtesy of Floridata

Literature Cited

Animal Feed Resources Information System. Date Unknown. Solanum lycopersicum. Accessed 2003 March 31.

California Tomato Commission. Date Unknown. Home Page. Accessed 2003 April 1.

Cox, S. 2000. “I Say Tomayto, You Say Tomahto...” Accessed 2003 March 30.

Dave’s Garden, Inc. 2003. Tomatoes Database. Accessed 2003 April 1.

Dave’s Garden, Inc. 2003. Tomatoes Database-lycopersicum. Accessed 2003 April 2.

Florida Tomato Committee. 2002. Home Page. Accessed 2003 April 1.

Floridata. 2000. Lycopersicon lycopersicum. Accessed 2003 March 30.

GardenWeb. Date Unknown. “What is the difference between "determinate" and "indeterminate" tomatoes?” Accessed 2003 March 30.

Peet, M. 2001. Sustainable Practices for Vegetable Production in the South – the Tomato. Accessed 2003 March 31.

Schuchert, W. Date Unknown. “Tomato (Lycopersicon lycopersicum).” Accessed 2003 March 31.

United States Department of Agriculture, Natural Resources Conservation Service. 2002. PLANTS database. Accessed 2003 March 31.

Image Courtesy of
California Tomato Commission

Author: Jessica "GB" Green-Barnes
Last Revised on: 4 April 2003

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Earlham · Biology Department · Biology 226: Biological Diversity

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