Horseshoe Vetch - No seed produced (1 Viewer)

At our local nature reserve (Howell Hill in Surrey) there is a single patch of Horseshoe Vetch which covers a little more ground each year - it is currently about 2m in diameter I suppose. The strange thing is that although it is visited by lots of insects, it never produces any seed.

I seem to recall reading somewhere that some plants are not self fertile, i.e. they need to be pollinated by pollen from a genetically different individual. As our patch is probably all derived from one individual, I wondered if this could be the problem? If so, I presume the solution is to introduce another plant from elsewhere to become a near neighbour?

Any thoughts welcome.

Yaffle

Yaffle said:

I seem to recall reading somewhere that some plants are not self fertile, i.e. they need to be pollinated by pollen from a genetically different individual. As our patch is probably all derived from one individual, I wondered if this could be the problem?

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I am sure you are right, Yaffle. I don't know if they've been worked out In Horseshoe Vetch, but in Red Clover, another member of the pea family of course, there is a quite complex set of alleles of an incompatibility gene, and a plant cannot be fertilised by pollen carrying a same allele as it already has itself.

In Wigtownshire there is apparently a similar problem - there is, as far as is known, only one plant of Purple Oxytropis (Oxytropis halleri) left on the Mull of Galloway (by some distance, its southernmost locality in Britain). It flowers well, but doesn't produce seed.
Frustratingly, while we accepted there was only one plant left, a local botanist told me a few years ago that the single plant, along with its cliff ledge, had broken away and fallen into the sea. I checked, and the single plant was alive and well. Maybe we actually had two plants, but nobody had seen both of them!

It would be possible to supplement the population from further north, but doing that might well bring different genes into a long isolated population - when there is a chance that other surviving plants may still be found somewhere along two miles of sheer and crumbling cliffs!

The argument might be different for your Horseshoe Vetch as it seems like it is a recent arrival anyway - and it is the foodplant for Chalkhill and Adonis Blue butterflies.

Alan

Alan,

Thanks, I think this is most probably the problem and so we need to look at introducing one or two different individuals from elsewhere.

In fact we are fortunate enough to have the Small Blue butterfly visit this patch most years. I believe that its larvae feed on both the flowers and seeds of Horseshoe Vetch, so anything that helps seed production will also assist this small population of butterflies.

Regards,

Yaffle

Yaffle said:

In fact we are fortunate enough to have the Small Blue butterfly visit this patch most years. I believe that its larvae feed on both the flowers and seeds of Horseshoe Vetch, so anything that helps seed production will also assist this small population of butterflies.

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Sorry, but I think you are wrong on that. So far as I know, the Small Blue uses only Kidney Vetch as a foodplant.

Nice butterfly though.

Alan