Reading seed catalogues just isn't what it used to be.  Seems like every year, a few more cryptic terms, abbreviations, and secret codes creep into to seed sellers' description of something as simple as a cucumber.  Here are  translations from my latest crop of seed catalogues, and what they mean to you.

Let me say up front - concrete and clear definitions can be very hard to find.  Consider double-digging into your seed seller's web site for more information.

Heirloom
IMHO "Heirloom" is the most misused, misunderstood term in gardening.  There is no legal (or even universally accepted) definition of an 'Heirloom' plant variety.  I remember when,  "Heirloom" referred to any plant variety that had been on the market for a long period ( usually at least 40-50 years) of time.  But this definition has morphed.  In most seed catalogs today,  "Heirloom" and "Open Pollinated" mean the same thing. 

Open Pollinated
 An Open Pollinated plant variety is pollinated as a result of a natural process such as honeybees, wind, motion,  and humans imitating nature (think hand-pollinating a small backyard plot of corn).  Seeds saved from an open pollinated plant WILL "breed true", producing offspring (and fruits/vegetables) similar to parents.

Hybrid

 "An F1 hybrid (or filial 1 hybrid) is the first filial generation of offspring of distinctly different parental types" (Wikipedia). Seed catalogs often designate hybrid varieties as "F1" (Filial), "F1 Hybrid", or  simply "Hybrid".  Plant breeders develop a hybrid variety in order to achieve certain commercially valuable characteristics such as disease resistance, transportability, color, etc.  Seeds saved from Hybrid varieties WILL NOT "breed true".  For example, a seed saved and planted from a hybrid tomato will produce unpredictable/unreliable results. Under the Federal Seed Act, seed package labeling must clearly indicate if the contents are "Hybrid". 

GMO - Genetically Modified Organism

Using biotechnologies,  scientists can create a  GMO plant variety by transferring selected genes from one organism to a target organism. These organisms are not necessarily similar. The resulting GMO variety will have characteristics  of the combined genetic material. A recent example is the "Roundup Ready" gene developed my Monsanto for their soybeans.  Because of the introduced genetic material, a Roundup Ready soybean is not affected by Roundup Weed Killer.

NOP or OG (Organic) Seed Coating
Some sellers offer seeds with coating. This coating helps gardeners when planting very tiny seeds like lettuce and carrots. National Organic Program (NOP) compliant coating is clay based and is certified organic.

PVP - Plant Variety Protected
PVP is a complicated and controversial subject. Under the Plant Variety Protection Act a plant breeder may "protect" plant varieties meeting four important criteria. The saved seeds from a PVP certified variety may not be used/sold/resold for commercial purposes. Seeds may be saved for personal use only. Reimer's Seeds Lumina Pumpkin is a PVP example.

Utility Patent
Plant breeders may obtain a utility patent on a plant variety based on certain criteria.  This is similar to a device or process patent.  For these varieties, seeds may not be saved under any circumstances - not even for non-commercial,  personal use.  An example of a Utility Patent is Johnny's Selected Seeds "SalaNova" lettuce collection.

HR, IR, Disease Resistant Codes, and Genes
In some cases, a plant name will be followed by an alphabet soup of mystery letters.  This is usually:  A) a list of resistant diseases; or B).  certain beneficial genes present in the variety.  Some catalogs simply state a plant variety is Resistant for listed diseases. Other sellers use “HR” (High Resistance) and “IR” (Intermediate Resistance) followed by disease code(s) to indicate a degree of resistance.  A tomato seed product with “HR: VFF IR: EbLb” has High Resistance to Verticillium Wilt (V) and Tomato Fusarium Wilt (FF), and Intermediate Resistance to Early Blight (Eb) and Late Blight (Lb).  To make things even more confusing, some catalogs base their disease codes on a Pathogen List published by the International Seed Federation. Other sellers use their own disease codes. So, disease codes can vary from catalog to catalog.   One last, and very important, thing to remember.  "Disease Resistant" does not guarantee Disease Immunity.

MT<number>
Mosaic Viruses can infect a large number of garden plants.  Specific virus resistant varieties are available (usually hybrids).  'MT' followed by an code indicates results of a Mosaic Virus test.  Here's an example for tested lettuce.  MT0 30 indicates 0 seeds out of 30,000 tested positive for Lettuce Mosiac Virus (LMV).  NOTE:  Buying a "Mosiac Resistant" lettuce seed, will not be effective if the crop is attacked by a non-resistant Mosaic Virus strain.

DM: <Downy Mildew races if known>
 'DM' indicates Downy Mildew resistance.  Races are specific forms of the mildew spores.  DM: EU 23 - 27 indicates Downy Mildew resistance for Races 23,24,25,26,27 of Eustoma.  Keep in mind, Powdery Mildew and Downy Mildew are different conditions.

The Federal Seed Act
The labeling of vegetable seeds is regulated by the Federal Seed Act as well as a host of individual state regulations.  "The FSA requires that seed shipped in interstate commerce be labeled with information that allows seed buyers to make informed choices."  This includes specific notation on the seed package label as well as record keeping requirements for the seller.  See the FSA site for details. 

No doubt about it - seed buying for humble backyard gardeners is becoming more complicated. If we want to know what we are buying, we’ll have to keep up with seed catalog jargon. I’m pretty certain, these annual translations will only get harder as years pass.