runner x common bean crosses

In an earlier posting I’d stated that I thought I’d gotten a cross between a runner bean and a common bean:

Thanks to a couple of articles I’ve found I can confirm that such a cross happens, and even give some idea as to how. The answer is that those Carpenter Bees I love so much are the likely means to that ends.

First up, a review of the bean in question:

Cross of Purple Pod and Runner beans?

Cross of Purple Pod and Runner beans?

Top is a dry Scarlett Runner Bean pod, bottom is a set of three normal sized common beans (2 purple pod, one Cherokee Trail Of Tears). The ruler shows that in between are some 19 cm long ( about 8 inch) Giant Purple Pod beans.

In that prior article I’d noted:

My beans are regularly visited by a bunch of pollinator species. 4 kinds of bee, a couple of different humming birds. The cross pollination delivery was there. But who knows.

I’ve seen a bumble bee (fuzzy body and all), a European Honey Bee, and what was originally thought to be 2 kinds of carpenter bee, but in fact are the two sexes of xylocopa varipuncta, also known as Valley carpenter bees, as discussed in this comment:

So who crossed what with whom can be a bit of an “issue”…

Speculation Ends

There were three articles I ran into on crosses of Phaseolus Vulgaris and Phaseolus Coccineus. They pointed out that:

a) It can be done and has been done.

b) As the Phaseolus Coccineus tends to open the flower before pollinating, it crosses out well, but as the Phaseolus Vulgaris tends to “self” prior to the flower opening, it tends to not cross … UNLESS the flowers have been “serviced” by carpenter bees that tend to open a hole in the flower to get to the pollen and can deliver some “coccineus” pollen to a “vulgaris” that has not yet “selfed”. Thus my beans with a purple pod “mom” and runner bean “dad”.

Runner beans are usually grown as annuals (I’ve just sown what I hope will be an early crop) but they are perennials in the wild and if you can keep the roots frost-free through the winter they’ll produce a second year’s growth, albeit with inferior pod production. If you are of a curious nature and fancy some amateur plant breeding you could try crossing French beans with runner beans, by carefully removing stamens from French bean flowers with fine tweezers before they shed pollen and then pollinating the flowers with runner bean pollen a day or two later. The cross works with French beans as the female parent, but not the other way about.

I would question that it can go “the other way about” as I’ve got some slightly odd “pods” from the runner bean that I think just might be that other way. Only 3 total seeds, but still, it’s a start…–the-variation-of-f2-progenies-derived-from-interspecific-crosses-between-phaseolus-vulgaris-and-phaseolus-coccineus

The variation of F2 progenies derived from interspecific crosses between Phaseolus vulgaris and Phaseolus coccineus

Anton IVANČIČ and Metka ŠIŠKO
pp. 19-25

Interspecific hybridisation within the genus Phaseolus represents an important source of genetic variation which can be very useful in breeding programmes based on recurrent selection. The aim of this investigation was to analyse the phenotypic variation and relationships among the most important quantitative traits in F2 generation materials derived from crosses P. vulgaris x P. coccineus. P. vulgaris was used as female while P. coccineus as male parent. The F2 material was composed of 825 individuals which originated from open pollination of 65 F1 plants. The most variable quantitative trait was the number of flowers per inflorescence, which varied from 0 to 57 (CV = 45.8 %). The second was the inflorescence length which varied from 2.5 to 74 cm (CV = 39.0 %). The highest value (CV = 70.4 %) was obtained for floral colour (a qualitative trait which was transformed into a special numerical scale). The correlation analysis showed that there were close relationships among the number of leaves, number of flowers, number of pods, number of seeds and the length of the growth period. For practical breeding, the most useful is probably the correlation between the number of inflorescences and the number of seeds per plant (r = 0.503 and 0.560) because the number of inflorescences can be easily determined at the beginning of the hybridisation period, and the number of seeds is more or less directly associated with the yield. For the final visual selection, at the end of the vegetation period, the most useful trait is the number of pods, which is highly correlated with the number of seeds (r = 0.740 and 0.916).
Agricultura 2: 19-25 (2003)

So, the point of this posting?

Pretty simple, really.

It shows that the cross can happen. That it goes in the direction that I seem to have achieved. That it is typically effected by tweezers or similar surgical intervention, and we know that the carpenter bees do just such a procedure to get to the pollen and nectar in flowers too small for them to enter.

I really like my bees ;-)

There is an interesting story here:

from someone else who got such a cross. It looks, from their story, like I may need to spend a while “stabilizing the cross”.

Posted by galina england (My Page) on Mon, Feb 18, 08 at 20:04

Farmerdilla and Zeedman, you wrote:

The runner beans (P. coccineus) will cross with each other but not limas or common beans. (snip)

It is rare, but runner beans and common beans can and do cross. I had a cross several years ago, and it has been fascinating. At first I did not recognise what was happening – a common bean with red and pink flowers? But the flowers looked different from runner bean flowers. The pods were short, rough skinned, sparse, late maturing and the few black seeds they contained were of irregular size and distorted shape.

The following generation I had some cotyledons in the ground and some above. And the most exquisite flower colours imaginable. Peach, pink, purple, pale blue, apricot. The resulting beans were smooth podded and quite variable in type and yield, including just a single yellow pod on one of the plants containing two tiny seeds. One germinated and I got a very strong growing tall plant with large yellow pods and large brown seeds. Another of these second generation hybrids produced small seeds but with the same markings as the runnerbean that I suspect to have provided the original pollen.

All of the offspring of the cross have become much heavier bearing than the original cross. They still have remarkable flower trusses, but the colours are more muted now. They grow strongly and produce very well, especially later in autumn, when the ordinary beans and the runnerbeans have stopped. So far the hybrids haven’t really stabilised much. I most often get black seeds now, but some are white or other colours.

It is rare, but if you get a chance cross, it is fun following it up, even though the first filial generation isn’t very promising.

The F1 of my beans have been planted out for a while now. Way too early. (It has been much colder than “typical”). I’ve lost 3 out of 6 plants to various cold and / or hungry critter issues (probably also from the cold and reduced food sources). At this point I have three of them about 5 foot tall (and still growing! At least on warm days…) with very pretty (though small) purple flowers and some with pod set.

I still have about a dozen seeds to play with as the season warms. I would like to get some of the F1 matured before I risk the “archive” seeds, though.

All in all, it is still an adventure. But know I have a bit of an idea about the “how” and the “why” of it all.

Here is a picture of the “first flower”. It is now a small pod about 2 cm long ;-)

Purple Bean Flower V x C

Purple Bean Flower V x C

Shortly after this stage it opens and becomes a lighter more violet color. As you can see, the same gene that codes for “purple flower” also codes for “purple in the stem” (and a bit of purple cast to the leaves). I think there are 3 total flowers in that picture. You can pick them out by the three shades of purple.

All in all, a beautiful flower.

So far all of the F1 have the “vulgaris” style of holding the cotyledons out of the soil. We’ll see if the F2 continues that trend (probably next year). So far it looks like “mom” gives the cotyledon style and color of pod, while “dad” gives an overall more intense color and larger seed size. As we move to the F2 generation, that could get more “mixed up”…

Again, “well see”.

That I’m getting pod set, even in the cold weather I’m having, is an encouraging sign. The purple pod vulgaris beans are known for being cool soil tolerant, and the runner beans are known for setting pods in cool weather. IFF I’ve done what I hope to have done, I’ve got a fairly cold tolerant bean that will set pods and make beans even in this “60 F or so with overcast and sporadic rain” type of weather. (It is raining again today… Very nice April weather… in late May…)

Add that to my “Kalards” that have done a wonderful job of “self sowing” and are now making plenty of greens, and I’m well on my way to a cold tolerant garden with adapted species that will give me both greens and seeds. Edible pods and dry beans.

“Just in time” variety creation… Gotta love it!

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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9 Responses to runner x common bean crosses

  1. Doyle says:

    Amateur science at it’s finest. I can’t wait until I’m in a place where I can indulge my curiosity like you do.

  2. E.M.Smith says:


    Just takes a single pot and some seeds ;-)

  3. Level_Head says:

    Ah, and most of the technical and creative types—like you and many of us—have had to stifle a certain amount of disdain for bean counters.

    You’ve managed to bring technical creativity to the process of producing more and better beans to count.

    That certainly counts.

    A good show; thank you, sir. May your gardens stabilize at high productivity, and your flowers delight the discerning eye.

    ===|==============/ Level Head

  4. Judy F. says:


    I have worked for years as Superintendent at our county fair in the Horticulture division. That is a fancy title for the person who enters the veggies and assists the judge. However, those of us who work there have each had years of experience in our own gardens and have grown and experimented with many types and kinds of seeds as well as various growing conditions and climates- which is why we volunteer at the fair because we love gardening. Every year we have some exhibitor bring in a veggie that they swear is a certain variety. It looks nothing like it is supposed to. Usually it is some kind of cross in the Capsicum ( sweet or hot peppers) species, but sometimes in the Cucurbit ( cucumbers and melons) family. The oddest speciman that I’ve seen, looked like a very large ribbed lemon cucumber, soft, lightly textured skin with small spines, with the flesh color, seed placement and void similar to a cantaloupe. We thought perhaps the exhibitor was onto something, but alas, it tasted like dirty water…

    The peppers are more closely related, so they seem to cross with more ease. We see a wide range of sizes and shapes that don’t conform to the “standard” of a particular variety or the picture on the seed packet. Mother Nature has lots of tricks up her sleeve when it comes to plant breeding and bio diversity.

  5. E.M.Smith says:

    @Judy F:

    You’ve got it!

    What we “think we know” about genetics is a far cry from what actually happens. Genes flow on their own. Move from individual to populations, and from populaitons to species, and even from one species into another. Constantly recombining. That’s the whole trick of evolution.

    You would likely enjoy this story about a watermelon pumpkin cross:

    To expect things to stay “true to type” is to be fighting a constant battle. It is the “keeping it true” that’s hard. Finding the “odd bits” is easy. Deciding which “odd bits” are worth keeping is golden…

  6. Jason Calley says:

    @ E.M. “Genes flow on their own. Move from individual to populations, and from populaitons to species, and even from one species into another. Constantly recombining. That’s the whole trick of evolution.”

    Yes, and now we have allowed patents on specific genes. Lawyers (and some courts) have interpreted this to mean, “anyone who owns a plant that has this gene is a criminal unless they have already paid a royalty to the patent holder.”

    We cannot keep genes from spreading:

  7. E.M.Smith says:

    @Jason Calley:

    Just one of the reasons I think we are not mature enough to handle GMO produce…

    It is an incredible disaster that we get to watch unfold over the next few hundred years.

    Both biological and legal disasters…

    As a person with allergies, I’m just dreading the day I find out that a protein to which I am allergic has been put in rice and all the rice products become poison to me. (For example).

  8. Jason Calley says:

    @ E.M. “As a person with allergies, I’m just dreading the day I find out that a protein to which I am allergic has been put in rice and all the rice products become poison to me. (For example).”

    Yes, that would be bad enough… but how about this. How about the day you find that corn has a gene added to it so that your kids or your grand-kids will never have any children of their own?

    Or the day that you find the human sterility gene in corn has jumped to other species of plants and is, literally, loose in the biosphere?

  9. I agree, amateur science at its best, it is this kind of curiosity that has got the human race where it is today.

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