Plant Names & Def•i•ni•tions

By Paula Ogilvie:

The growing season has started. How do you find the best plants and seeds for you? Always take a moment to read descriptions in catalogs or on plant tags.

Is the fruit or vegetable noted for its taste, shelf-life, or vigor? (I personally choose taste.) Next look at the hardiness zone to see the coldest winter temperatures the plant can survive. Colorado has 5 different zones so find yours – often available by zip code. Mountain growing zones are different than the Front Range (mostly 5B) or Western Slope.

Also note days to maturity. From last average spring frost to first average fall frost is the growing season. Sometimes seasons are longer and the next year, shorter. In the fickle Colorado weather a plant requiring a long growing season might not produce vegetables. Keep a log or journal and you’ll begin to understand your garden. Nature doesn’t follow our rules; we need to understand hers and be patient.

The term endemic refers to a plant’s native region. For example, there are nine types of Datura or Angel’s Trumpet. Some are endemic to dry southwestern regions and can be easily grown in Denver gardens, others come from the tropics. One yellow flowered Datura can be grown outside in summer but must come indoors in winter. Plants that are endemic to Southwestern North American or Mediterranean climates often do well in our region. This information is not always on the label so check the zone.

Plant terms like hybrid, F1 cross, variety, heirloom or GMO can be confusing, especially if you just want a ‘regular’ plant or maybe an improved variety. Naming is set up to make communication universal so names in Colorado are the same as in California, Maine, or Texas. Once you understand the basics choosing plants will be much easier.

Plants have a binomial Latin name. The first word is the genus (plural, genera) and always capitalized. The second lower case word is the species. Both are usually in italics. For example, corn is Zea mays.

Seeds from plants that are open pollinated, whether by bee, butterfly, moth, bird, or wind, produce a plant that looks the same as the parent. But natural variations often occur within species and the resulting plant’s seeds will produce plants that resemble the new parent. Red bud trees have a pinkish red flower but a naturally occurring variety has white flowers. It’s designation is Cercis canadensis var. alba. (Note that variety is abbreviated and alba means white.)

Breeding by farmers, horticult­ur­ists, or home gardeners can obtain specific plant traits by deliberately crossing two different varieties through hand pollinating. The resulting plants are called hybrids (F1 generation, or “first children”). It may take a few generations for the desired trait to appear. Seeds from these hybrids don’t usually produce true to parent and seeds are not usually saved, though some may carry the desired trait. Think back to high school biology and the Austrian monk Gregor Mendel experimenting with garden pea plants. Hybrid names are capitalized and usually in single italics. For example, a yellow milkweed hybrid is called Asclepius syriaca ‘Prairie Gold’. Hybrids are not GMOs.

Clones are identical new plants propagated from cuttings, plant divisions, grafting, and tissue culture. Plants like strawberries that send out runners are another clone example. The new plants have the exact same genetic information as the parent. Hybrids can also be cloned using these methods. Tissue culture involves taking a few cells from the desired plant and growing a new plant in sterile conditions using plant hormones. It’s a much faster and cheaper way to obtain a specific result, especially for commercial growers. Orchids are often cloned since seeds take years to grow into a flowering plant. The downside is a potential loss of the genetic diversity contained in seed grown plants.

Heirloom or heritage plants have remained unchanged or stable for at least 50 years. Flowers can be open pollinated and remain true to the parent type. Brandywine tomato, Solanum lycopersicum, is an example. Within any population some natural hybrids may occur and those with desirable traits can be chosen as cultivars (short for “cultivated varieties”). Cultivars remain true to the original if propagated by humans. There are cultivar heirloom brandywine tomatoes with yellow fruit. A desirable cultivar is sometimes called a selection – a consumer term, not a botanical one. Selections can be chosen from naturally occurring or hybrid varieties.

Genetically Modified Organisms (GMO) refers to precise breeding where a new gene is inserted into an existing organism in a laboratory setting. This bioengineering sometimes uses genes from different phyla; genes of fungi, bacteria, or even animals are sometimes inserted into plants. In theory the practice is to improve quality, whether for disease resistance, herbicide resistance (as in Round-Up Ready crops), nutrition, or commercial production, but the pros and cons are still under much discussion when it comes to our food. Proposed GMO tomatoes were stopped in 1997, but there are now GMO varieties of summer squash, apples, potatoes, and papayas in the U.S. Most commercially grown corn, soy, canola, and sugarbeets are of GMO origin. It is still unlikely that home gardeners will come across GMO seeds or plants. Search the internet for a list of seed companies that have signed the “Safe Seed Pledge” organized by the Massachusetts-based Council for Responsible Genetics.

Many new gardeners today are wary of all hybrids, prefering only open-pollinated and heirloom plants. While some heirlooms may taste better or be genuinely desireable plants, hybridization by humans (as the pollinator) has been practiced for a very long time and has been occurring naturally forever, sometimes with excellent results.

Before retiring, Paula Ogilvie taught college level botany and biology. She was a STEM advsior at Community College of Denver and former educational director and adult program specialist at Denver Botanic Gardens.