Yellow Sugarsnap Project ... lots to report

Don't get too excited, this one looks very pretty but it's actually a yellow mangetout (snow) and only has one of the two recessive genes I'm looking for

There's been so much happening with the Yellow Sugarsnap Project, and so much else happening in the rest of my life, I haven't had a hope of blogging up all their progress. One issue is that I'm collecting huge amounts of data which I'm then having to type up and spend ages staring at, in addition to all the usual seasonal garden activity. So this is the best I can do for the moment. At least it'll give you a glimpse of what is happening with the project, which has reached its most exciting stage now.

A couple of years ago on this blog I claimed that naturally inbreeding plants such as peas don't show much hybrid vigour, if any. Well I'm having to eat humble pie now as my yellow sugarsnap F2 hybrids soar beyond a height of 7ft and show no interest in slowing down. They've massively outgrown the frame I made for them and are beyond the tops of the support sticks. This project is a cross between a 5ft variety and a tiny dwarf one which barely reaches 1ft in height, so I wasn't expecting anything quite like this. D'oh!



The original cross was Golden Sweet x Sugar Ann and this is the F2 generation.

Some things have turned out just as predicted ...

Flower colour is usually pretty simple in peas. Purple is dominant over white. So if you cross a white-flowered variety with a purple-flowered variety, the first season's progeny (F1 hybrid) should all have purple flowers ... and that's exactly what happened when I grew the F1 generation last year. In the F2 generation the genes are recombined, and approximately a quarter of them end up with the pair of recessive genes which enable white flowers to express themselves. So I expected to get purple flowers on three quarters of my plants and white on the others. And that's not far off what I've got. Hurrah!

I already showed you the first flower, which was purple (when I say purple, I mean the mauve and maroon bicolour which is common to many heritage varieties). The next four were all purple too, and then the next four were whites. A majority of the early flowers were white, but overall the ratio is 24 whites to 39 purples, which is not quite a Mendelian ratio but is not wildly far off it.

The joy of F2 variability. Sometimes they're white-flowered with a cream calyx and yellow stems ...

Sometimes they're purple-bicolour flowered with green calyx and stems ...

And sometimes it's the other way around.

Yellow pods are a recessive trait in peas, and again the inheritance is pretty simple because it's all down to a single gene. In a cross between a yellow-podded pea and a green-podded pea, all the first generation (F1) plants should be green-podded (and indeed they were). In this F2 generation the recessive yellow gene has a chance to assert itself and so roughly one in four plants should have yellow pods ... and so far that's pretty much what I've got. 19 yellows to 44 greens is as near as dammit the predicted Mendelian ratio.

It's quite odd to see these yellow and green pods all growing together, and to think that they're siblings from the same batch of seeds. Gene segregation in action!

Snap pods are another recessive class, so again I'm only expecting about one in four. In some cases it's still too early to tell which are sugarsnaps and which are mangetouts. Many of the mangetouts are obvious because the pods are already large and flat, but I haven't finished collecting data on this yet so there's no point drawing any conclusions. But at a glance I'd say the ratios are looking about right.

Tall plants outnumber dwarf plants considerably, which consist of 6 true dwarfs and 7 intermediate types (13 altogether). The expected ratio is three talls for every one short, because once again it's a trait which usually shows simple dominance.

Yellow tendrils grow alongside green tendrils, another variable trait in the F2 plants

Some new things I discovered, but they weren't huge surprises ...

There is a correlation between axillary pigmentation and purple flowers. All the plants with a deep pink splodge in the leaf nodes (whether it was a tiny smudge or a big blotch) went on to produce purple (bicolour) flowers, while all the plants with no trace of pigmentation went on to be white-flowered, no exceptions. Not entirely unexpected, although theoretically I can't see why these traits shouldn't be inherited independently because they're controlled by different genes. Maybe it's gene linkage, but I don't know to be honest. The genes controlling purple/pink colouring in peas are numerous and sometimes interrelate in funny ways.

A trait common to all purple bicolour pea flowers is that they turn a beautiful blue as they fade

There is a correlation between cream or yellow colouring on the plants and yellow pods, so all the plants showing any trace of yellow colour are turning out to be yellow-podded. No exceptions so far. The surest sign is when the first flower buds begin to form, because the buds have a very distinctive pale cream calyx (that's the leafy bit round the outside of the flower that looks like a pixie hat) which is easily recognisable even while they're still tiny. It's interesting that there appears to be just one gene controlling yellow colour, and it's an all-or-nothing kind of thing. Not like purple, which has separate genes (or even pairs of genes) for colouring different parts of the plant. It seems that if the yellow gene is there, you can expect to see yellow consistently in the stems, tendrils, calyx, pods and young leaves.



Pods per node is variable, as in many other pea varieties. Some bear their pods singly, some in pairs, and some show a mixture of both on the same plant.

And some things which were a pleasant surprise ...

New phenotypes are the most exciting aspect of breeding your own plants. Crossing any two varieties, especially those with a healthy bit of genetic diversity, is likely to throw up a few new traits not seen in either parent. It happens because genes interact with each other in a variety of ways and some can only express themselves when they hit just the right combination. While it's nice when all your predictions and ratios come out correct, it's not as exciting as seeing something totally wacky and unexpected show up in the F2.

So you can imagine how delighted I was to be presented with this:

New pink and white flower phenotype, which is essentially a white flower overlaid with pinky-mauve, giving a veined and mottled effect

This is the rear view ...

... and they age very gracefully too, producing more colours as they're going over.

Six plants out of the 63 are showing this new phenotype. What appears to be happening here is that the standard petal (the big one at the back) is white but the pinky-purple is trying to assert itself over the top. As the pink is stronger in the middle it gives this beautiful mottled two-tone effect. The same is true of the wing petal, where the maroon is spattered over a creamy white base. The overall effect is absolutely beautiful, and looks more like something you'd see in sweet peas than culinary ones. I really like this new type and would love to have a new variety like this, even though it's nothing to do with the original purpose of the project (distractions and sidelines are part of the fun).

The burning question is whether I can actually preserve this new phenotype in future generations and make a true-breeding stable variety out of it. The reason I'm uncertain is that I don't know what genetic factors are responsible for it. Maybe if I save seed from all the pink-and-white plants they will happily produce offspring with the same attribute, in which case I will be hopping up and down with joy. If, on the other hand, the unusual colour is created by co-dominance between two opposing colour genes then I'm stuffed ... because the genes will recombine and segregate out into pure white types and purple types. I would still get some of the pink-and-white types, but they would decrease with each generation and no amount of careful selection would be able to fix those colours.

There's more interesting stuff about these pink-and-whites. You may recall that when I sowed the seeds I separated them out into different seed types, according to their colour, wrinkliness and whether they had purple speckles. I did this so that I could look out for any correlation between seed type and plant traits. For the most part there hasn't been anything obvious, but ... four out of the six pink-and-whites are from Group 2, which was "smooth, green seeds with purple speckles". The other two are in a group which were selected for size rather than colour, so it's not possible to know what colour seed they came from, but they both came from the "small seeds with indeterminate markings" group.

And that's not all ... I'm intrigued to find that all six of the pink-and-whites have the sugarsnap pod type. Given that the sugar pod gene is recessive, it seems unlikely that it's simply down to chance. But I don't know what the explanation is. The most obvious is gene linkage. That's something which happens when genes are positioned close together on the same chromosome ... they tend to stick together rather than being inherited separately. The closer together the genes are on the chromosome, the less independent they tend to be. So it may be that one or more of the genes which make pink-and-white flowers (and of course I don't know anything about these genes yet) is on the same chromosome as the sugarsnap gene. And I have no complaints about that. I prefer sugarsnaps to mangetouts anyway, so if this is going to turn out to be a pink-and-white flowered sugarsnap by default, well, suits me.

There are other new phenotypes too, even if not quite so exciting. Here's another of the very pretty ones, a dwarf plant with exceptionally intense yellow colour. It's even got yellow leaf veins. The bicolour flowers have an unusual rolled tube shape. Pods are yellow mangetouts.



And the yellow sugarsnap itself? At the moment it looks like I have only one plant which is a true yellow sugarsnap (others may become apparent later, but I think that's the lot). This isn't entirely surprising ... there is only a one-in-four chance of a plant having yellow pods, and of those, only one in four are likely to have the recessive sugar-type pods. So overall that means a 1 in 16 chance of a yellow sugarsnap. Out of 63 plants I might have hoped to get more than one, but when you look at it from a statistical point of view it's not that wide of the mark. Better one than none at all!

The holy grail of this particular breeding project, a Yellow Sugarsnap.

For those who want to see the actual data I'm collecting on these plants I'm compiling them into a huge table and making it available online (on what will eventually be an extension-website to this blog but it's very much a work in progress). I'm still collecting data so the table isn't yet complete.

If you're inspired by what you've seen here but still thinking "what the heck is she talking about?" I heartily recommend a read of Carol Deppe's book, which is where I learned half of what I know (the other half coming from the garden itself). There would be no Daughter of the Soil without Carol Deppe!

More French beans than you can shake a stick at

A diversity of beans. I grew all these varieties in the garden last year. Top row, left to right: Coco Bicolour, Nun's Belly Button, Early Warwick.
Middle row: Purple Queen, Purple Prince, Mrs Fortune's.
Bottom row: Spagna Bianco, Vermont Cranberry, Caseknife.

Beans are a joyous thing to grow. They make such a big fanfare when they emerge from the ground. Huge fat fleshy cotyledons which don't look like leaves at all. And then a slightly prehistoric appearance as the true leaves unfold from inside. You can't miss 'em. And neither can the slugs, unfortunately.

I'm having serious problems with the slugs at the moment, as a lot of other Brits probably are. We've had a lot of alternating heavy rain and bright sunshine, which has brought the plants (and weeds) on a treat. Lots of fresh new growth = gastropod party time. After a drawn-out and very dry spring season, a dousing of rain has suddenly brought them all out of hibernation and they are hungry. All my breeding projects are under assault. Ulluco, razed at ground level every time a shoot emerges. I've lost my entire crop of onions, which included some rare and hard-to-get varieties, and it's too late to start again. Nurtured since January, wiped out in a single night.

Young bean plants are very vulnerable when first planted out. Some snails like to work their way up the stem stripping off the outer layer, and then pointlessly chomp through a leaf stalk so the whole leaf falls off. Other times the slimy little sods don't bother with all that and just shin up the bamboo cane to mangle the leaves directly.

I've been planting out loads of beans this week and I'm doing my best to keep them alive. I have had to sow a few replacements, but hopefully if we have a few days of dry weather the survivors will get properly established and the slugs will cease to bother them. I've collected rather more beans than I've got room to grow but I'm managing to find space for most of them, and the rest can wait till next year.

French beans in Rootrainers. The emerging seedling is Poletschka (thanks Celia) which grows from amazingly beautiful indigo-black glossy seeds ... and the pink stems beside it belong to Jo's Purple Podded, an ongoing breeding project distributed by the Irish Seed Savers Association.

Most of the varieties I'm growing are climbers. I don't grow very many dwarf beans because of the slug problem ... the low-slung pods are easy pickings for them. I also find the yields very poor for the amount of space they take up and they often give back barely a handful more beans than I sowed to start with. But there are some interesting varieties which don't have any equivalent among the climbing types, so I make an exception for those.

Two new dwarfs I'm trying this year are Black Valentine, a variety from the 1850s with small but pretty black kidney beans, and Comtesse de Chambord with even smaller shiny white beans. Indeed Comtesse de Chambord is something very different, as it's what's known as a rice bean ... the white beans are tiny enough and elongated enough to look a bit like rice grains (pudding rice, anyway). Actually they aren't quite that small but they're pretty tiny as beans go. They're reputed to have an excellent flavour but they're not grown commercially because their tiny size and delicate plants make them uneconomic. So if you want them you have to grow your own. I got my seeds from Association Kokopelli.

Newly emerged seedlings of Comtesse de Chambord, which look a bit like little bug-eyed monsters while they still have their yellow cotyledons. They grow into small, delicate plants of a very bright green and the pods can be used for green beans or left for shelling.

By way of contrast, these are the emerging seedlings of a supersize Australian climbing variety called Purple Giant. This one is mainly grown for its purple pods and the seeds are flat and fairly small. With the weather being so clement they've grown rapidly in the last few days but I can't plant them out yet because I don't have any tall enough poles. I can only buy bamboo canes of a maximum of 7ft because anything bigger than that won't fit in my car. I'm having to borrow some extra-long poles from my neighbour. He has a bigger car.

Purple Giant emerges. The one on the right is more strongly purple than all its siblings, though otherwise it looks true to type.

I'm always on the lookout for natural variations and mutations in beans, because breeding them the same way I do peas is not convenient ... the anatomy of the flowers makes them incredibly difficult to hand-pollinate. However, some of the most dramatic variations are no use for breeding because they're not genetic.

That includes the curious phenomenon of occasional bean colour reversal, or "day for night" to give it a more romantic name, where (for example) a batch of tan beans with purple markings has the occasional purple bean with tan markings. Many heirloom varieties seem to display this trait. Last year I picked out all the "day for night" beans from a batch of Mrs Fortune's and sowed them separately. The result was exactly the same as if I'd sown any normal Mrs Fortune's beans, i.e. the usual colour and a few with reversed colours. Afterwards I spoke to a couple of other bloggers who had had the same experience, picking out the reversed beans from other varieties only to find they grew into the same plants regardless. So something other than genes much be responsible for the colour reversal, but what? Moisture levels inside the pods and exposure to light and air during harvest might be factors, but in all honesty I've no idea.

More bean diversity. Top row, left to right: Jo's Purple Podded, Black Valentine, Lazy Housewife.
Middle row: Canadian Wonder, Dog Bean, Poletschka.
Bottom row: Pea Bean, Kew Blue, San Antonio.

iiiiit's ... PURPLE!

Oooh, this is getting exciting

Well, it is for me anyway.

Pictured above is the first flower bud on one of my F2 peas, in this instance Golden Sweet x Sugar Ann, my yellow sugarsnap project. The only other pea in the garden currently producing buds is Alaska, whose synonym is Earliest of All. So this one is very early. Both the original varieties in this cross are fast maturing, Sugar Ann particularly so, but it's likely I'll see a bit of variability in these F2s.

This project is a hybrid between a white flowered and a two-tone purple-flowered variety, so the F2 plants are likely to segregate into different flower colours (the F1 generation were all purple as that's the dominant gene). It's too early to tell what colour this flower will be, but so far it looks very, very like a Golden Sweet flower. It has a yellow penduncle and a creamy-yellow calyx, which are both Golden Sweet traits, as well as the obvious yellow tinge to the young leaves. I can see a tiny bit of pink colouration on the inner petals of the bud, so I think this one is going to go purple.

I have just today seen two other plants in this F2 batch producing tiny flower buds. Not like this one though, they both have a green calyx and look more like Sugar Ann flowers. The creamy-yellow calyx is a recessive trait so most of the plants will probably have the green ones.

Can't wait to see this flower open!

Garden gallery ... late April

Once again I'm posting some nice pictures while I'm too busy to write anything more considered. Yes I know there's a couple of greenfly on that orange tulip. But we are an organic garden and we are tolerant.

Lots of peas on the go at the moment. I have tall peas - Sugar Magnolia with its manic tendrils ...

... and short peas - Gravedigger ...

... and some new seedlings. The green ones are another breeding project in the making, an F1 from Magnum Bonum x Carruthers' Purple Podded. I don't know what I'm looking for or what I expect from the cross. It's just that they are in my opinion two of the best peas available, an outstanding heritage greenpodder and the best tasting and most beautiful purple podded. And they were both flowering in the garden at the same time last summer, so it made sense to cross them. To the right of the picture are some peachy-coloured seedlings of Spring Blush which is related to Sugar Magnolia and has the same alien-head hypertendrils.

The apple blossom on all the trees is lovely, and smells distinctive too. Tewkesbury Baron is quite strongly scented.

Many people grow and enjoy the heritage Crimson-Flowered Broad Bean, and rightly so, it's a superior variety. But the seeds I bought in 2005 from W. Robinson & Son showed a mixture of flower colours: pale pink, dusky pink, mauve, two-tone pink/charcoal black, as well as the expected red. I assume the seed stock had been accidentally crossed with a more common black-and-white flowered variety, and this was probably the F2. Not that I mind at all. They were absolutely beautiful, to be honest. It was quick and easy to eliminate the pinkness by saving seed from the best reds, so I'm assuming the red-flower gene is a good hearty dominant. But I like the pink ones too, so I saved some seed from those separately. And here's one of them just coming into bud. Isn't it lovely?

Why I love out-of-date seeds

The gardening question which never seems to have an answer is "how long do seeds keep?" The reason it has no answer is that there are so many variables ... how the seeds were harvested, processed and stored, what type of plant it is and probably also an element of luck. Tomato seeds keep longer than carrot seeds, for example, but there are no hard and fast rules. You just have to try them.

Take the little beauty in the picture above, photographed last month ... a very rare dark pink Estonian potato-leaf tomato called Siniy. This one came as a freebie from Association Kokopelli as part of their giveaway of out-of-date seeds. I've photographed the seed packet beside it so you can see the date on it: 1998. That's right, this healthy little tomato plant grew from seed which had been sitting in an envelope for 10 years.

Admittedly germination is no longer 100%. I sowed three seeds and only one germinated. But that's enough to give me a whole new generation of seeds if this plant survives to maturity. Tomatoes are naturally inbreeding, so saving seed from a single plant (although not ideal) is not a problem.

I'm not necessarily recommending out-of-date seeds as being better than, or even as good as, fresh seed. Old seed often has sporadic or very slow germination, and sometimes the plants which do grow are a bit weak and wobbly. But there are many good reasons to keep hold of those old packets.

There's not always much point going to the trouble of rescuing old seeds when you can just go out and buy new ones, but I often find myself needing to make the effort. Sometimes I get hold of old seeds of rare varieties which can't easily be replaced. Very often I get seeds in small quantities so I can't afford to waste any.

This is one of the very few areas where I disagree with Monty Don, who advocates throwing away any seed packets more than a year old and buying fresh ones. His reasoning is that fresh seed germinates quickly and grows rapidly ... which is true enough. Except that the whole idea of "new" seed being "fresh" is a bit of a myth.

Association Kokopelli have a policy of labelling their seeds with the year they were grown, but that's unusual. "Sow by" dates on commercial seed packets are sometimes arbitrary and meaningless. Patrick at Bifurcated Carrots wrote a very informative post about this a little while ago. When it says "packeted in year ended ..." that's exactly what it means – packeted. What year it was actually grown is another matter. As Patrick explains, the seed is likely to have been produced in a single batch in one year and sold as required. A germination test is done and if the seed passes the test then it gets packeted up and sold. The "sow by" date is based on the validity of the germination test and is not necessarily an accurate indication of the freshness or shelf-life of the seed.

And naturally seed companies are in no hurry to correct the common misconception that out-of-date seed is unviable, and that you need to go out and buy another lot.

In the UK and Europe, where dunderheaded legal restrictions govern the availability of vegetable seeds, readily available varieties often get dropped from the Common Catalogue and when that happens they can become very rare very quickly. The Heritage Seed Library keeps an eye on "deletions" and steps in to rescue them as necessary, but things can slip through the net. In other words, it's possible that the crumpled seed packet you've had languishing at the bottom of your seed tin for years may now be an endangered variety.

Another good point is raised by Soren of In The Toad's Garden. If you save your own seed, there is often a risk that a crop might accidentally cross-pollinate with another variety. Not that that's always a bad thing ... it's potentially the start of an exciting new variety. But if you're growing heritage varieties and need to keep the variety pure it can be a disaster. Soren keeps a few generations of seed for each variety, so when an accidental cross happens he can just go back to his seedbox and start again with seed from a couple of generations earlier, before the cross happened.

Tomato seeds are especially good to save long term, as they really do last for years. I'm still getting 100% germination from some seeds I scraped out of a Marks & Spencer's tomato onto a piece of kitchen roll in 2002. Back then I didn't know how to save tomato seeds properly so I didn't follow the usual recommended method and ferment them. But what the hell ... they still germinate.

Beyond the realm of vegetables, some seeds stay viable for very long periods. Last year, with a little expert care, some seeds from botanical specimens found tucked inside a book for 200 years were successfully germinated. And seeds of the common wild poppy are thought to remain viable for up to 100 years. The incredible display of poppies which bloomed on the First World War battlefields in the years immediately following the armistice was a mass germination of dormant seeds in the soil. Poppies are adapted as a cornfield weed and are sensitive to soil disturbance, so four years of pelting with mortar shells was just what they needed to trigger them off - generations of accumulated seed suddenly brought to life.

There have long been claims about peas found in Egyptian tombs still germinating after thousands of years - though personally I'm sceptical about that. It was a well publicised scam in Victorian times which seems to have kept resurfacing over the years.

Association Kokopelli sometimes give away packets of old seeds, and I have a lot of fun coaxing them into life. With such a large catalogue of varieties, they inevitably have a stock of unsold seeds which have passed their expected germination time. Rather than throw them away, they give them to gardeners to take pot luck with them. At the moment, for every five packets of seed you buy from their UK website you get a free packet of "old" seeds of the vegetable of your choice. Some don't germinate. But a lot of them do. The Siniy seeds shown above (and incidentally that seedling is now a fine healthy plant) was one of the packets I got free with Dominique Guillet's book a couple of years back. Other 8, 9 and 10-year-old tomato seeds I've had from Kokopelli are also germinating fine.

I also have a selection of old seeds from Association Kokopelli's pepper collection. Pepper seeds, in my experience, are not as long-lived as tomato seeds. Some of mine are five years old and not germinating. But the trouble with peppers is that they are very very slow to germinate, and need good warmth and moisture. It's not easy to keep them constantly warm and moist for a month or more, especially when moulds are likely to thrive in similar conditions. So here's what I've been doing to "resurrect" the slow-germinators.

An attempt to salvage some old seeds of Georgia Flame, a mildy hot pepper. The brown tint in the kitchen roll is tea! Using tea to assist pepper germination is a tip I picked up on the excellent Chileman website. (Sadly I haven't been able to germinate these.)

I cut a thin strip of kitchen roll (that's paper towels to American friends), fold it into a small square and wet it with warm water from a recently boiled kettle. A drop of tea is even better. Then I place the seeds within the folded square and put the whole thing inside a small sealable polythene seed bag. Making sure the seal is tight, I put it somewhere near a radiator and leave it for ages.

As you can see in the picture, the advantage of this method is that you don't have to keep opening the bag to see how the seeds are getting on. If you keep opening and resealing the bag, the contents will go mouldy in no time at all. But left sealed it should stay fresh for weeks. You check the seeds by holding the bag up to the light. Any sprouts emerging will be clearly visible. Once the sprouts emerge you will have to unseal the bag and plant them within a few days.

A Hungarian Semi-Hot pepper seed brought back from the dead after spending over a month on a bit of moist kitchen roll in a sealed bag. Nothing happened for a month, and then four germinated over the following couple of weeks. Not bad from what had appeared to be a packet of dead seeds.

Pea update: purple mangetouts

F2 plants from a cross of Golden Sweet x Carruthers' Purple Podded. The colours are stunning when the sun shines on them.

Pictures speak louder than words with these, I think. These are for the Real Seeds purple mangetout project, F2 seedlings from two crosses: Golden Sweet x Desiree and Golden Sweet x Carruthers' Purple Podded. Hopefully a majority of them will turn out purple podded, and from those I hope to find some which have the recessive mangetout pod type. Mangetout peas lack the gristly layer of fibre on the inside of the pod.

All the parent varieties used in this project have purple colouring in one form or another, so it's not surprising that all the F2 plants are showing purple colour. Theoretically they should all be genotype AADD. It is variable though. Some plants have a dark purple axil splodge, some have red edges or red flushes on the leaves, some have rosy stems and tendrils.

They're all beautiful.

Golden Sweet x Carruthers' Purple Podded with non-serrated red leaf margins, pink stems and green tendrils

Deep rose blush on stems and tendrils on a Golden Sweet x Carruthers' Purple Podded plant, and even on the back of the leaves. This one has serrated edges.

I suspect some of the strong purple colouring on these plants has been brought on by the intensely cold nights we've been having. They've been snowed on and endured two or three hard frosts. Tough little things.

Some of the plants have serrated leaf margins, similar to the yellow sugarsnap project. They also share the tendency for dwarf plants to have darker leaf colour ...

Pink stems on a Golden Sweet x Desiree plant. This one is going to have a dwarf habit, it's very low and bushy and you can see the slugs have already been at it. Notice the dark green leaves compared to the yellowy green of the one in the picture below.

A big dark smudgy axil ring on a Golden Sweet x Desiree plant, which also has some purple spots on its leaves.

Pea update: yellow sugarsnaps

Jeremy said the eyes of the world would be on my yellow sugarsnap seedlings. Well, here they are Jeremy, I hope you like them (and the rest of the world does too).

The F2 plants are all slightly different but the differences are subtle at the moment. Purple leaf axil splodges are now showing up on a lot of plants as expected, although it's been slow to develop. The splodges indicate the genotype A_D_ and its assorted variants. A is the gene for anthocyanin production and D is the gene for the purple splodge. They are both dominant. The size, shape and intensity of the splodge varies from plant to plant though, so there are probably other genes at work too. Some plants have a cream band inside the purple one, some don't, others just have a faint trace of it.

This one (below) has no purple splodge in the leaf axil and no other purple or red marking so is presumably the recessive genotype aa. Whether it has D_ or dd I've no idea because D can't express itself in the absence of A. Ah, the joy of genes!


Another thing I've noticed. The dwarf plants have darker, grey-green leaves compared to most (though not all) of the tall plants, which are more yellowy-green. I have no idea yet whether this is genetic or caused by something in the environment, or an interaction of the two. The F2s have separated into dwarf and tall types in a beautiful Mendelian ratio despite the small sample size, and I planted all the dwarfs along the front edge of the frame so they don't get swamped. It may be that they're getting more sunlight, or it may be that their short stature concentrates the chlorophyll in a smaller area and makes them go darker.

If it is genetic, why would there be a correlation between short height and darker leaf colour? One possible explanation is gene linkage. Genes are arranged in long sequences on chromosomes, which break up and rearrange whenever a seed is produced, to form a new genome for that individual seed. Peas have seven chromosomes. If the gene for dwarf height is on one chromosome and the gene for darker leaves is on another, those genes will be independent of each other and will usually recombine freely in the offspring. But if the two genes are close together on the same chromosome, it's much less likely that they can be inherited separately. The closer they are, the more they will stick together. In addition to this, it's very common for genes to interact with each other and even for a single gene to have more than one function (pleiotropy is the technical name for it). Any of these factors could be involved.

Another possible explanation, of course, is coincidence. Just because all my dwarf peas have darker leaves, it doesn't necessarily mean there's a reason for it. As I said, it's a small sample size and I can't draw too many conclusions from it at this stage.


Almost all the F2 plants have got serrated leaf edges, but again there's variability in how strong it is. Some have subtle little points and spikes along the leaf margins while others are boldly zigzagged and look like someone's cut round them with pinking shears. One of the parent varieties, Sugar Ann, has boldly serrated leaf margins while the other, Golden Sweet, shows some variability. Most Golden Sweet plants have smoothly rounded leaf margins but serration does sometimes show up too. I assume there's a dominant gene involved here, which is either not fully penetrant in Golden Sweet or is interacting with other genes. My other breeding project involving Golden Sweet hybrids is showing the same thing, a strong dominance of serrated edges.

Everything I've written here is just idle speculation, I must emphasise. I no more understand the genetic make-up of these plants than I know what colour knickers the Queen is wearing. It's all down to observation and guesswork. I will probably have to grow another couple of generations of plants before I can draw any firm conclusions.

Pea update: general

This year's acquisitions from the Heritage Seed Library

Honestly, I've got so many interesting peas on the go at the moment I'm really struggling to catch up with writing about them. I still have to do a post about my original Purple Pea Project, but in the mean time here's a brief update on the ones I've already blogged about.

I'm quite excited by Sugar Magnolia. It looks so different from anything else I've ever grown, and its height is already apparent in the way it's towered up above all the other seedlings in the tray. The stems are a lovely deep pink and the tendrils are mad - see below. I assume Alan Kapuler named it after a song (by the Grateful Dead). I'm trying to come up with a title for my next album and wondered about naming it after a vegetable.

There's a carrot named after Hendrix's Purple Haze but I'm not sure carrots were the plant substance Jimi had in mind when he wrote the song. Though I suppose it looks carrot-shaped when it's rolled up.

Graham, who very kindly sent me the pea seeds, has sent me some more seeds of both Sugar Magnolia and Opal Creek, along with a third Kapuler pea Spring Blush. I think Spring Blush may have been a sideline which sprang up from the breeding work on Sugar Magnolia. It has the same hypertendrils, apparently, and similar height ... but instead of purple pods it has green pods with a purple stripe. Another great curiosity to look forward to, thanks Graham! If all goes well I will be able to share seeds of these varieties next year.

Hypertendrils. This is what they look like:


Many of my peas are now planted out in the garden and coping very well with the unseasonably chilly weather. At least the snails are not as big a problem as they usually are ... the very dry spring and the drawn-out cold have inhibited their activities considerably, so their numbers are pretty low at the moment. What I am having problems with though is keel slugs. They're those very small ones, often pale or pinky coloured, that live in the soil and come out at night to wreak unspeakable havoc among seedlings. They are far more destructive than those big ugly slithery jobbies you see on the garden path in the wet.

Oregon Trail has been the most severely damaged by the slugs and is a great example of why I generally avoid growing dwarf peas. Some of the plants are completely skeletonised, and none of them are looking good. The plants are so short the apical tip doesn't have a hope in hell of growing out of the slugs' reach. It's like a fast-food restaurant for gastropods.

Carouby de Mausanne is also being savaged, but as it's a tall pea I have every hope it will thrive. The apical tips are already well above ground level so the slugs are mostly just shredding the lower leaves.

I still have lots of F1 seeds from last year's hand-pollinations which need sowing and growing, and I'm also planning out what new crosses I can make this year. I was very impressed with Taiwan Sugar, a rare pale-pink-flowered pea kindly sent to me by Patrick: it's a mangetout (snow) type with a wonderful flavour and no string. But it's a very short dwarf variety and I've already explained what happens to dwarf peas in my slug-addled garden. So I'm wondering what would happen if I crossed it with a good tall mangetout, such as the voluptuous (white) flowered and gorgeous flavoured French heirloom Corne de Belier. A tall mangetout with pale shell-pink flowers and delicious sweet flavour would be a lovely thing to have ...