Thank you, Bo!
I forgot the bit about heirloom seeds. (oh, blab, blab, blab...)
Heirloom seeds are ALWAYS 'open-pollinated' seeds, called OP for short.
OP seeds are from plants that will make plants (mostly) like themselves IF they are not crossed with other varieties of the same type. An OP bean (for instance) can be crossed (accidentally or deliberately) with other beans of any kind, via insects, wind, birds, or pollen transfer from your clothes or tools. There will always be some variations within the same variety.
Heirloom seeds are those that the grower has been very careful not to cross with other varieties. Some heirlooms of the same kind have been taken to different parts of the country and maintained. Heirloom growers/savers keep an eye on their plants, and mark the best, earliest, biggest, sweetest, hottest or plain tastiest plant, and then save that seed and grow it again next year, again applying the grower's taste for what he considers 'best'. In this way, growers/savers have created sub-varieties of the same plant that are best suited for their particular climate. It is perfectly reasonable that a grower of 'Golden Bantam' corn in Michigan has created a slightly different variety of that particular corn, better suited to his climate, from a grower/saver who lives in Arizona, who has done the same for his climate.
Many heirloom plants have been carefully netted to prevent access by insects, and have been hand-pollinated by the growers.
The seed is the 'child', and it will grow as the breeding determines. If the pure-seed plant is crossed with another variety (desirable or not), this only affects the NEXT generation of seed, NOT the currently-growing fruit. The pure squash seed that I bought and planted last spring turned into exactly the squash that was advertised. But I am not saving the seeds because I had some gourd plants in the same yard, and I took no precautions against the pollen of the gourd crossing with the squash. If I did save the squash seed that was produced, it would be likely to produce a fruit that was nothing like what I planted and ate last year.
Heirloom and OP seeds both help to guarantee a wider genetic diversity, a 'bank account' of seed genes. Mankind can't know which genes are most likely to be beneficial in the future, so a wide genetic seed base can help to insure the continuation of as many genes as possible.*
OP seeds can be crossed to make new varieties or to create hybrids.
Hybrids are the results of crossing two or more varieties to create specific characteristics. In seed catalogs, hybrids are often referred to as "F-1 hybrids". The problem with creating hybrids is that you always need the same sequence/parents to produce the hybrid child. And there are several kinds of hybrids. Seeds from hybrid plants almost never 'breed true' to produce the same kind of plant as the hybrid parent, so are rarely worth saving.
Some people think hybrids are in the same class as genetically-modified plants. This isn't true. Hybrids, good, bad or indifferent are all created by simply crossing the pollen of one plant with the stigma of another. Insects and birds have been creating hybrids for millions of years. People have been doing the same for somewhat less time.
Genetic modification as defined by three sources on the Web:
"The alteration to an organism's genome by any number of methods, including inserting, transferring, or deleting genes or other DNA sequences." (pbi-ibp.nrc-cnrc.gc.ca/en/media/glossary.htm)
"Genetic modification shall mean modern biotechnology used to alter genetic material of living cells or organisms in order to make them capable of producing new substances or performing new functions." (ec.europa.eu/research/biosociety/library/glossarylist_en.cfm)
"... the process whereby a genetically modified organism is made in the laboratory. This involves making artificial or modified genetic material (GM constructs) which are inserted into the genomes of cells or embryos. ...
(
www.i-sis.org.uk/Glossary.php)
There are certain 'parties' who appear to be attempting to control the world food supply by forcing GM plants, animals and products onto people who don't want them, people who think that a severely limited world seedbase is a recipe for disaster (mass starvation), that GM creations are causing more problems than they are likely to ever solve, are far more expensive than advertised, and their pollen is spreading farther than the scientists promised they would, and are already contaminating related plants and varieties via worldwide wind pollination.
Sue