I guess you need to clarify on some terms. For garden plants, "species" can cover a lot of ground (so to speak!). Brassica, for example is a species that includes plants as different as cauliflower and kale, kohlrabi and brussel sprouts. All the "varieties" in that species will "cross", IOW, a flowering brussel sprout can reproduce with a cauliflower in flower about as easily as with another brussel sprout. I believe that yes, any cross is technically a "hybrid". There are so-called "natural hybrids", such as rutabaga - the result of a long ago cross between the cabbage and turnip families, both members of Brassica.

Then there are intentional hybrids, such as created for gardeners. "Open pollinated" is a term used to distinguish from those, varieties that are not created hybrids but rather have been in stable easily reproducible form for many generations. That does not mean that they won't cross with other varieties of their species, however.

Open pollinated simply means that the subject plant has stable genes. all plants of that cultivar will have the same characteristics. The offspring of those plants, unless other genes are mixed in, will have the same characteristics. If genetics from another cultivar added than you have cross pollination. Two cultivars usually from the same species that interchange pollen will make a new hybrid that usually has some characteristics of each parent but not always. Sometimes one is dominant and the other shows up in subtle ways. All carrots for example are the same species (Daucus carota) but if you cross pollinated a cultivar with bright orange coloration with a white cultivar, you get something in between. and yes it will be a hybrid until it is interbred for several generations and the selected characteristics are stable. Ditto for tomatoes, that is how we have thousands of cultivars. Tomatoes as you stated are not as rampant natural cross pollinators as other species, but they do do cross pollinate. Most tomatoes are the same species, exception being the current tomatoes.

Thanks.. Your knowledge is helping to clarify this for me. So to add to a knowledge of pollination using carrots again, for example, if two plants from the same variety of carrot (Nante), pollinate one another is that termed "cross pollination"? Or is that simply pollination. I know !! nitpicking perhaps, but it is a fascinating topic.

As far as open pollination goes when is a plant considered to have a stable genes esp. if insects and the like are freely pollinating and could mix in other pollens?

Of course, some plants must cross-pollinate, or you won't get any fruit -- apples, for example. If you have two apple trees of the same variety (for example, Macintosh), you won't get any apples. If you have one Macintosh and one crabapple, you will get apples -- but if you plant the seeds from those apples, you'll get a Macintosh-crabapple cross, which may or may not be edible. If you want another Macintosh tree, you need to have a graft from a Macintosh tree. All trees in each named apple variety are clones of each other.

Neither term - cross pollination or open pollination - is really applicable to carrots. ;) Blooming veggies - yes. Root veggies - not much. Root veggies such as carrots and potatoes don't require pollination to produce since it is the root we are eating.

The terms in question would only be relevant to carrots IF you let the tops go to seed and want to save the seed for planting next year. Then the purity of the seed will depend on the variety grown as carrots require insect pollination. Wild carrots are self-fertile, domesticated garden carrots aren't. So if Nantes is all you are growing and you want to save seed from them then your Nantes will be open pollinated by each other. And Nantes is considered an OP variety because it has been stable for over 100+ years.

However if you plant another variety of carrots next to them - say Sweet Treat Hybrid - and let them both bloom and go to seed then 5-10% of each will likely be cross-pollinated by insects. The Nantes will still mostly breed true even if crossed because they have very stable dominant genes.

Hope this helps some. ;)

Dave

To the plant, pollination is pollination. To the gardener who wants particular results (such as wanting to keep an heirloom variety pure), cross-pollination (cross-breeding) is something to avoid. To a grower or scientist who is trying to create a new variety, cross-pollination is desirable. It's all on your point of view.

Like Dave said, some varieties are very genetically stable, like his Nantes carrots. Others, like curcubits, are notorious for cross-pollinating. If you're growing certain kinds of decorative gourds, and zucchini or other squashes, insects will cross-pollinate them very easily, and if you saved the seeds from your wonderful zucchini and planted them, they could end up being something almost unrecognizable and tasteless.

"Does cross pollination always create a hybrid?"
Yes and no. Technically, every pollinated plant is producing a hybrid, because every plant from every seed has a tiny, microscopic difference from the plant next to it, although it is, for most purposes, the same. Only cuttings, cloned or tissue-cultured plants are exactly the same as the parent stock. Plants labeled 'hybrids' have been crossed from plants with noticeably different qualities. If you crossed two of these 'hybrids', they would most likely revert back to the qualities of one or the other of the 'parents'. Granny Smith apples came from crabapples. If you planted a Granny Smith seed and nutured it for several years, you would probably end up with some sort of crabapple or similar variation.

Two additional bits of info (just to confuse you a little more ;-) ):

1) You can be growing two similar plants near each other, but if they flower at different times, they won't (can't) cross-pollinate. Corn is a good example: there are early, mid-season and late varieties of corn. Corn cross-pollinates easily because it's wind-borne, but if they tassle (the 'flower') at different times and there is no other corn around (esp upwind), they won't cross. If Alfie's apples (above) needed a pollinator variety, and he accidentally planted a variety that bloomed a month after his Macintosh, he wouldn't get any apples.

2) OP varieties can be 'manipulated' even within the variety. You can have a packet of seed of a single variety of an OP plant, and each seed inside will have a tiny difference about it. Many people will grow a particular variety that they like, and they will watch for 'special' ones among that variety: a tiny bit earlier, a slightly larger fruit, a sweeter flavor, a slightly higher yield, etc, and they will mark it and let a few fruits of that plant mature and collect the seed. The next year, they plant that seed, and again look for 'special' plants. Every year, they keep doing this, and end up (hopefully) with localized variety within a named variety that is especially suited to their local conditions. It's still the same variety, it's still OP, it's just an improved variation within that variety.

If you bought seeds from a grower in BC, and you bought the same variety from a grower in ON, the local seeds might produce plants that had a slight edge on local conditions, concerning earliness, adaptibility to hot summers, or ability to grow with a bit less water. The seeds from BC might adapt better to cooler summers, more humidity, and a longer season.

Thanks to all for the great help re. pollination et al.
It has become clearer to me the more I read.
How fortunate that this site exists.
Happy gardening.