The issues associated with cross-pollination are often over-whelming for those new to seed saving. ;) But honestly, is is a very minor concern unless one is into manual hybridization of new varieties. Are you looking to create new hybrids or just save some seeds?

Calling a plant "perfect" isn't really accurate nor is the other term sometimes seen - "complete".

What is at issue is whether or not the particular plant is self-fertile (self-pollinating). Plants that are self-fertile means that each bloom contains both the male stamen and female pistil needed for self-pollination.

It is easy to determine which plants are self-fertile by browsing the many lists available on the web of "self-fertile flowers" or "self-pollinating vegetables" etc. Or just Googling them by name. But the easiest way is to learn the parts of the flower so that you can tell just by looking if the flower in question has all the need parts.

Self-fertile, self-pollenizing vegetables include: tomatoes and all related family members such as eggplant and peppers, bush and pole beans and limas, English and Southern peas, radish, and cabbage.

Plants that are not self-fertile, those that require insect or wind pollination cannot be prevented from crossing except by isolation and/or bagging blooms and hand pollinating them and even then it isn't perfect but most species will only cross with members of the same family.

If seed saving is your goal, and I assume it is since this is the forum for that ;) then you need to understand that 1) the odds of natural (done without manual intervention) cross-pollination in self-fertile plants is very slim, and 2) for most seed savers it isn't a big concern ;) unless they are manual hybridization (into creating new species under controlled conditions), 3) insect-vectored plants such as members of the squash family will benefit from bagging and hand pollination to maintain purity.

So one must first know if the specific variety is a hybrid whose seeds likely won't breed true even if it does or doesn't cross or is it an open-pollinated variety. CP cross-pollination is only an issue with OP varieties, and if it is an OP does it really matter if it does get CP? No, because the odds of it happening are so minimal.

Hope this helps.

Dave

It helps. I am interested in saving seeds, not creating my own plants yet lol. Although it IS fascinating, and something I may do someday.

My main concern was preserving the heirloom strains I plan to grow of beans and tomatoes, as well as the colors of hollyhocks.

I dont have near enough room for distance isolation, so wondered if all my different heirloom tomatoes and beans would cross with each other if not bagged.

Also, I was intending on planting many colors of hollyhocks in close proximity, and wanted a way of ensuring I could save seed and still get the same colored plants as ones that I like the color of.

Does this make sense? You sound as though if I just want to save the seeds, I needn't worry about "self pollinating" plants crossing with other variety OP plants of the same family, but posts on GW led me to believe that this can and will happen. Is that wrong?

Is it wrong that self-pollinating plants may cross? No. But the odds are minimal so not really a concern for the average home gardener/seed saver.

And, as said above, the more vital concern arises only if you are trying to intermix self-pollinating heirlooms with self-pollinating hybrids for some unknown reason - then you do have potential problems. Stay away from hybrids in other words since you wouldn't want to save their seeds anyway.

You'll find numerous discussions on CP in tomatoes over on the tomatoes forum and the percentage of CP is repeatedly quoted at less than 5%. This is because self-pollinating blooms usually finish pollination before the bloom even opens.

I have grown OP tomatoes, numerous varieties at a time, for close to 40 years and in that time I've run into maybe 4 or 5 CP seed. Dr. Carolyn Male (noted author on heirloom tomatoes) says the same thing when she posts there. For that reason - slim to none odds - most tomato seed savers don't bag their blooms. Commercial seed suppliers, yes, home garden seed savers, no.

But then we don't grow just 1 plant of a variety at a time or save seed from only 1 fruit on the plant either. 2-3 plants of each and varietal seed is saved from several different fruit from different plants of that variety. That cuts the odds of getting a CP seed to less than 1%.

Beans have a slightly higher % of cross - depending on the variety - but again, only with other plants of their same type (unless you were to inter-plant different varieties in the same row for some unknown reason ;). But again, like tomatoes, CP is easy to control by 1) planting 1 variety at a time, 2) separating varieties by several rows of other vegetables, or 3) simply staggering the planting dates of different varieties.

Hollyhocks - I don't grow but because of the size and shape of the bloom and their attraction to pollinator insects, inter-mixing colors can easily result in color changes in the seed produced even if they are self-pollinating.

There is simply too much insect and wind activity with them to prevent it. But then it would be difficult to bag hollyhock blooms anyway and would look pretty unattractive. The best solution is to plant in patches of color and try bagging some blooms deep within the color patch to save those seeds. But the rest are going to re-seed themselves anyway so from everything I have ever read about them, maintaining color purity in a patch is nigh onto impossible - that is why the sterile one color hybrid varieties were developed. ;)

Hope this helps.

Dave

Ok, thank you again. This post helped me even more. I was indeed intending to plant mixed rows of different species of beans side by side... now I see I will have to modify that plan. I was planning on growing 5-6 bean varieties, one variety per grouping of poles, with the poles set up in one long row against the back of my house. Now I see that won't work. I guess I will have to just plant some beans here, and some beans there lol, and at different times too I guess.

Pollinators abound in this yard, as we have two hives of honeybees in the yard, just waiting to mix up all my pollen lol.

This seed saving just gets more confusing everyday.

Angela,
Just clarify the word usage. Perfect is not to describe plants. It is a correct word to describe the flowers. Flowers that are self-pollination containing both male and female parts are called perfect. They need no insect intervention to develop seed. Imperfect flowers have only male or female parts and need insects to complete pollination.
Remy

Can anyone reccommend a good book on basic genetics, pollination, etc for common veggies and flowers?

Hi again Angela,
For vegetables, I recommend 'Seed to Seed' by Suzanne Ashworth. For flowers I don't know a good one. When you need help with flowers though, you can check The Seed Site. It is the best web site. If you can't find the info there, most of the time someone can help you here : ) Usually when no one can help, it really is an odd plant or something that no one saves seeds from very often.
Remy

In my garden (central Ohio), tomato fruits tested from the first trusses (first flowers) showed that 30% of the fruits were cross pollinated and the proportion of crossed seed within those fruits was up to 12% of the seed.

I expect that later in the season when halictid bee activity increases both of these values would go up. Mid season halicted bee visitation counts showed me that each blossom was contacted by bees about 20 times a day, and blossoms were open for only 2-3 days indicating rapid pollination. General plant studies have shown that a bee will transfer more than enough pollen on one visit to pollenate all of the seeds in the ovary, but since the stigma of the tomato flower also contacts its own pollen before the flower completely opens you should NOT get 100% crossed seeds in any one fruit if a bee gets to it.

The iridescent green halicted bees I have around here are smaller than the anther cone of the flower and only stay at a flower for a second or two so they are hard to see if you are not looking, bumble bees are relatively rare and were not seen every day.

Halicted and bumble bee populations depend on both food availability and habitat for ground nests so there should be a lot of variability depending on your surroundings, and you should not assume minimal or 5% cross pollination rate. Many types of fruit trees (apple, wild cherry etc) and wild flowers open well before flowers of most vegetable crops so don't expect bees to be wholey absent early in the season.

The problem for home growers is that we generally only grow a few plants of each variety so unless there is a big change in a crossed plant you won't be able to tell the difference the way you could if you had a dozen plants of each variety to choose from when you go to save seed the next year. Pollination of bagged blossoms is lower than unbagged blossoms (most work, but you strike out here and there), but you don't need that many seeds for your own use to keep your own plants pure.

>

This was what I was talking about. I was not wanting to bag all blossoms on my plants, just maybe half the blossoms on 2 plants. Just enough to save some pure seed from my heirloom varities.

I'll check out that book, Remy, thanks!