Rex, With all due respect, it doesn't matter if you think that zucchini, which is Cucurbita pepo, will cross with Butternut squash, which is Cucurbita moschata, because it will not. I won't even address your zedonk example because that involves animal genetics and we're discussing plant genetics. You can't mix apples with oranges. You have to understand the Cucurbita genus a little better, which contains 12 or 13 different species or species groups, of which 5 OR 6 are domesticated species grown for food but of those, only 4 species of squash are grown by most people. Here is the key: each Cucurbita squash species (moschata, pepo, argyrosperma, and maxima) crosses with other squash within its species (and each species has dozens of individual varieties) but the species do not cross with one another, with one notable exception that I'll explain in a minute. So, people who save seed can indeed grow one pepo variety, one maxima variety, and then EITHER one moschata variety OR one argyrosperma variety with no fear of them crossing. With the C. moschata and C. argyrosperma combination, you possibly can have cross pollination, but only if the C. argyrosperma is the female and the C. moschata is the male. You don't get the reciprocal cross. With these crosses, there is little research about how/if they do or do not cross in home gardens because the research has been done with wild squash and Mexican cushaw types, and most people don't grow those types in home gardens. People who have cross-pollination issues usually have them because they don't understand which varieties belong to which species. Each species has its own specific stem, flower, seed, and leaf characteristics. Here's a very brief description of what they are. Cucurbita maximas have very long vines, very huge and hairy leaves, and somewhat soft, round, spongy, hairy stems. They produce seeds that are either white or tan with either cream-colored or tan margins and a thin cellophane type seed coating. The maxima species includes all varieties of Banana, Buttercup, Hubbard,, winter Marrow and Turban types. In her book, SEED TO SEED, which is the definitive book for folks interested in seed-saving, Suzanne Ashworth lists several hundred maxima varieties. Cucubita argyrosperma (formerly known as C. mixta) have spreading vines and large, hairy leaves. Each fruit's stem is hard, hairy and slightly angular. At the point where the fruit attaches to the stem, the stem flares out only very slightly. The leaves of C. argyrospermas are lighter in color that those of C.moschata, they have rounded leaf tips and few if any indentations along their sides. Their seeds are either tan or white with a very pale martin. The seeds have a thin cellophane coating and cracks in the skin coat on the seeds' flat side. C. argyrosperma includes most but not all varieties of Cushaw squash (excluding golden cushaw, orange cushaw and orange-striped cushaw which are C. moschata), and many other squash including native types like Gila Cliff Dweller, Hopi, Cochita Pueblo, Hopi Taos, and Hopi Teardrop. In her book, Suzanne Ashworth lists several dozen varieties from this group. C. moschatas have spreading vines and large, hairy leaves. With these, the fruit's stems out very noticeably at the point where it attaches to the fruit. The stem is very hard, somewhat angular and hairy. C. moschata's leaves are a bit darker than those of C. argyrosperma but they have pointed, not rounded, leaf tips and slight indentations along their sides. C. moschata seeds are small and oblong in shape, beige in color and have a darker beige margin. Within this species, you have all varieties of butternut squash, all varieties of of Cheese squash or Cheese pumpkins, and many others. Suzanne Ashworth lists probably a couple hundred from this species in her book. C. pepo plants have very prickly leaves and very prickly stems, and they are especially prickly by the time they mature. WIth these, the fruits stems are very hard at maturity and have five sharply angular sides. They produce cream-colored seeds that have white margins. This is a huge family that includes all varieties of Acorn squash, all varieties of Cocozelle, some but not all pumpkins, all crookneck squash, all scallop squash, all vegetable marrow squash, all zuchinni squash, and more. Suzanne Ashworth lists many hundreds of varieties that belong to this group and that includes many decorative striped and warted gourds. All squash varieties are outbreeding and are insect-pollinated plants. There techically are six species: argyrosperma, maxima, moschata and pepo as described above, and also C. ficifolia, a species grown in Mexico and used in candy-making, and C. foetidissima, a wild gourd commonly called Buffalo gourd. The name foetidissima is a clue that their leaves have an unpleasant odor. The fruit are used for oil (from their seed) but are not eaten. For seed-saving to be done properly to preserve the characteristics of each variety, you need to ensure a greater amount of genetic diversity by choosing your male and female blossoms from different plants of the same variety. If you save from a very small population of plants, over time you will have lower and lower quality of plants and fruit as you lose genetic diversity. I don't rely on anything I find on random websites on the internet because there is a lot of misinformation out there and often the info given is too general. I rely on books written by acknowledged experts and on info from university or agricultural extension websites. If you are truly interested in saving seed, you need to buy or borrow a copy of Suzanne Ashworth's book "Seed To Seed: Seed Saving and Growing Techniques for Vegetable Gardeners" which is the definitive book on the subject. If you are interested in the squash family, do yourself a favor and read Amy Goldman's outstanding book "The Compleat Squash: A Passionate Grower's Guide to Pumpkins, Squashes and Gourds". To save seeds successfully, you have to have a broad-based knowledge of the types of plants you are growing and a thorough knowledge of seed-saving and the techniques needed to do it properly. You need to know not only how to do it but also why it must be done a certain way. Simply hand-pollinating and bagging a few blossoms is a minimalist approach that can give you seeds that run out if you aren't careful. Running out means that you lose genetic diversity with each generation you save because you are saving too few seeds from too small of a population. What you consider simple and efficient leads to weaker and weaker seeds and plants over time and isn't recommended. I'm not saying that to be mean but just to emphasize that there's a better way to do it. Dawn

I have to cut and paste so I have a reference point and don't have to go back up to your original post. &&&&& (This volunteer tomato grew in my garden close to an area where I had previously grown Sungold, Gold Medal, Chocolate Cherry, Black from Tula, Japanese Black Trifele and Riesentraube tomatoes. I'm guessing it is either a rare cross between two of those or, perhaps, a reversion of the Sungolds? I guess it could have been planted by a bird from some distant neighbor. I would like any input you might have. The skin is almost translucent, pineapple-y yellow. They are shaped like miniature Gold Medals.) If it were a natural cross between any of the dark colored ones or Riesentraube, the F1 could not have been light coloroed since the dark ones and Riesentraube ( red ) have colors genetically dominant to light colors. Anyone I know who has had volunteers from Sungold F1 or from saved F2 seeds of the hybrid have gotten orange or red cherries. Red b/c the gene(s) for the flat truss trait are red. So I don't think a reversion of Sungold, which has many parental inputs, not just two parents. Other than a low flying bird, that leaves Gold Medal and Sungold as a possible cross. Small fruit size is dominant to large fruit size. I'm judging the fruit size of what you have by looking at your finger, and fruit size is much smaller than what one would suspect for Gold Medal, yet larger than anything Sungold sized. The fruits you show have no coloration consistent with the gold/red bicolor of Gold Medal/ And since small fruit is dominant to large fruiit, it could have been a natural cross between Sungold F1 and Gold Medal. I don't know the genetics of such bicolors like Gold Medal, so I'll suggest that it might be possible that the genes for the coloration of Gold Medal were not brought forward. One way to tell is to save seeds of what you show, put out as many plants as you can next season and see what you get. Other than that there's always the low flying bird theory, as you know. LOL Carolyn

If tomato varieties are planted in close proximity, pollen from one variety can land on the female part of a blossom, the stigma, of a different variety and lead to some or all hybrid seeds being formed in that fruit. This is commonly referred to as a "cross-pollination" or simply as a "cross." When cross-pollination occurs, the fruit will look perfectly normal in the current season; however, the resulting seeds carry genes from each parent and will produce varying progeny in subsequent generations. The word pollinator is usually used to describe the ways that pollen can be transferred from the blossom of one variety to the blossom of another variety. Pollinators can include wind, insects, mechanical vibration of the blossom, etc. Thus pollination describes the transfer of pollen between varieties, commonly known as cross-pollination. The word "pollenize" is usually used to describe pollen from a single blossom that fertilizes that blossom, thus this process is often called pollenization, to distinguish it from pollination, the transfer of pollen between the blossoms of two different tomato varieties. If you are not interested in saving seeds, then you can safely ignore cross-pollination issues. Tomato varieties will produce fruit consistent with the varieties planted. Again, any crossing in the current season affects the seeds within the fruit, not the fruit flavor or structure. If you are attempting to save seeds and maintain a pure tomato variety, some efforts must be taken to avoid cross-pollination. The extent and seriousness of your efforts will depend on the importance of the variety and its intended usage. If the variety is typical, widely available, or intended for home use, then you may welcome a cross as an interesting diversion. However, if the variety is a rare family heirloom, or intended for distribution as a specific named variety, then crosses must be actively avoided. Keep in mind that if a rare or one-of-a-kind variety is crossed, it will be lost forever. There is no way to fully reverse a cross. Tomato Reproduction Details Tomato blossoms are perfect, meaning they have both male and female reproductive structures. They are capable of pollenization without the aid of pollinating insects and without pollen from other blossoms. Tomatoes are an inbreeding plant but they do not suffer from inbreeding depression (loss of vigor in subsequent generations). Although not generally recommended, a tomato variety can be maintained by saving seed from a single plant. Some tomato varieties have exerted stigmas which means that the stigma is positioned outside of the anther cone and it is more susceptible to foreign pollen. Modern varieties generally have shorter styles so they are much more likely to pollenize. Style length is genetically determined but it can vary based on environmental conditions. Often, tomato blossoms pollenize prior to being visited by insects. This means that it is "possible" to get pure seed even when another tomato is directly alongside. Under normal conditions, most tomatoes have a natural cross-pollination rate of about 2 to 5%. Under some conditions though, this can be much higher - maybe as high as 50%. The incidence depends on the types of insects active in the area, the existence and types of inter-planted crops, the wind, the blossom structure, and the blossom timing of the varieties involved. The tomato ovary at the base of a blossom contains many ovules. The ovules can be fertilized by either pollen from that blossom or with pollen from the blossom of a different variety if there are unfertilized ovules available. Fertilized ovules become the seeds inside of fruits, so a single fruit could have both pure (pollenized seed) and also impure (cross-pollinated seed) within the same fruit. To maintain a "pure" variety, the grower must prevent the introduction of pollen from unrelated varieties. There are three basic techniques to prevent cross-pollination (1) protect the blossoms with a physical barrier, (2) grow plants at a time when other tomatoes are not blooming or insects are not present, and (3) maintain isolation distance between the varieties. Using Physical Barriers to Prevent Cross-pollination If you want to be absolutely sure that your tomato seed line remains pure, then you will want to provide a physical barrier to prevent foreign pollen from being introduced. The technique most often used by home growers is called "bagging." It is quite simple but it also is limited with regard to seed production. To "bag" a tomato means to cover the blossoms before they open. Various materials can be used. Some use floating row cover, others use tulle (bridal veil fabric), pieces of nylon stockings, sheer tricot or other lightweight fabric, or bridal favor bags. Depending on the size of the bags used, the bags must be monitored and removed after pollenization so that the tomato can grow to full size without restriction. After removing the bag, mark the fruit with yarn or a string to identify it when it has reached proper maturity for saving seeds. It is difficult to collect large quantities of seed using bagging. Fruits do not always form inside the bag. High temperatures and the lack of mechanical movement can hamper pollenization. Lack of mechanical movement is easily corrected by shaking the bagged trusses. If you are really serious, and you want a large amount of seed that is 100% pure, you could build isolation/screening cages as large as required to house the number of plants you desire. Using Timing to Prevent Cross-pollination If you can grow plants very early or late in the season so that tomatoes flowers are not available for cross-pollination, pure seed can be saved without any special efforts. This requires careful timing and growing only one variety to ensure pollenization (self-pollination). Aside from blossom timing. You can also gain a benefit from saving fruit based on the population of your particular pollinating insects. This requires a good knowledge of the insects in your locality. Using Isolation Distance to Prevent Cross-pollination A general rule is that the further apart varieties are grown, the lower the probability of cross-pollinating events. Experts disagree on the distances required. For most gardeners with limited area to grow plants, distance is NOT an effective means of obtaining 100% purity. Inadequate isolation, season after season, will result in some natural cross-pollination and may eventually produce undesired changes in the characteristics of a variety. There are no hard and fast rules to follow with regard to isolation. If you are knowledgeable about the pollinating insects in your locality, you may be able to design a system that reduces natural cross-pollination to a very low level with a small amount of isolation. If you lack specific knowledge about your locality, the following guidelines may be useful. Generally, tomato varieties should be isolated 20 to 25 feet, and they should have a pollen-producing crop planted between. The objective of the inter planted crop is to divert insects away from the tomatoes. The amount of natural cross-pollination will depend on the factors previously discussed. Generally, organic gardening methods result in many more pollinating insects than would be present in a area where pesticides and tilling have been extensively used. To obtain 100% seed purity by isolation distance, very large separations are required, possibly a 1/4 mile or more. Obviously, these resources and geography are difficult to achieve. Also, tomato volunteers from previous seasons could remain undetected within the isolation perimeter. Again, if you desire 100% seed purity, look to the physical isolation as provided by bagging or caging. If you rely on isolation distances, it's best to grow several plants of the same variety and if in a row, harvest fruits from the inner plants and if in a square area, from the interior plants. If only a few plants, it's best to harvest several fruits from each of the two or three plants for seed saving so as to minimize the chance of getting nothing but crossed seed if you chose only one or two fruits. Many varieties that are potato leaved and have large pink fruits often show very large double and triple blossoms early in the season which are quite attractive to insect pollinators, and some other varieties do the same. And sometimes the result is fused fruits. So it's best to not use fused fruits for seed saving since one or the other of the fused fruits could be cross-pollinated. Special Concerns regarding the Currant Tomato Home growers are growing more and more of what are called currant tomatoes, which are in a different species from our garden tomato. All currant tomatoes (L. pimpinellifolium) have exerted stigmas. Some folks highly recommend that you don't plant currant tomatoes near garden tomatoes ( L.lycopersicon) since they might serve as a source of foreign pollen in terms of cross-pollination. Others say that they'd worry more about regular garden tomatoes cross-pollinating currant tomatoes, and a third group might say that not all currant tomato varieties are of concern as regards cross-pollination. Recognizing a "crossed" tomato Depending on the varieties involved, it may be quite difficult to realize when one variety has crossed with another. Sometimes its easy to tell that something went wrong because the tomatoes are far from your expectations. Other times, you may not notice any problems until you begin seeing off-types in the F2 generation. Just remember, growing your seed out the first year is not always a 100% verification that your seeds are pure. Credits: This FAQ is a collaborative effort of Gardenweb members. Specifically, Bets, canadiantomato, Carolyn137, Earl, Fusion_Power, gardengalrn, Gardenmama1, JHCaden, Korney19, Paul2101, vaped Illustration by : Paul2101 Bagging Photo by : Bruce_B References : (1) Isolation distances for Tomatoes, Jeff McCormack; Ph.D (2) Breed Your Own Vegetables, Carol Deppe (3) Seed to Seed, Suzanne Ashworth

In my limited experience, saving seeds w/out bagging I have not observed any cross. I gather that tomato cross pollination is very low if not rare unless there are heavy insects activit, plants are very close and you get a lot of wind. A flower's own pollen is right there, next to the stigma and have many times higher chance to self pollinate, before the birds and bees wake up and come along lingering. hehe sey