Please pardon my ignorance but could some one please explain what this is and probably more importantly why... I have germinated loads of oranges, lemons and grapefruits and regularly get two seedlings, one larger, one smaller, sprouting from a pip and have sometimes had 3, the third very small.

I have separated them fairly easily once the tallest has grown to about 2-3" but the smaller ones always seem to remain smaller.

Any help greatly appreciated.

Richard

Richard, most types of citrus can produce embryos asexually (clones of the mother plant) in the same seed as a zygotic (sexual) embryo. Usually the asexual embryos are more vigorous and often even crowd out the zygotic embryo so it doesn't develop into a seedling.

It is also possible for twin zygotic embryos to develop, just like identical twins in mammals, but it is much more likely that you are seeing asexual seedlings with possibly some zygotic ones in there too. I would guess the ones that stay smaller forever are probably genetically that way.

You said it right, it's citrus poli embryony. Of all the embryos, one of them is derived from pollination (hence it can be some kinf of hybrid), all the others are called nucellar: they are identical to the mother plant. It's because of this that it's quite probable to have a plant identical to the mother by planting a seed. More than one can germinate from one single seed.

OK, thanks for all that. So.... the largest seedling is likely to be the clone of the parent and more likely to be true to the sort of fruit I took the pip from?

The smaller ones are a hybrid then and I can't tell what they are going to be like if they ever fruit?

The smaller ones do grow but much more slowly. I've worked out, not unsurprisingly, that the largest seedling has the largest share of the original pip. Separating them has proved reasonably easy provided I don't wait too long until all the roots are intertwined.

OK. Thanks again.

Richard

I like your wording about the larger one... "likely to". The smaller ones could be clones or they could be hybrids.You'll find out when they grow up and have fruit!

The Citrus Industry has some data about different trees' production of clone ("nucellar") and zygotic seedlings; as you can see, even trees of the same variety differ in this ratio. So you never know for sure what you are getting.

http://lib.ucr.edu/agnic/webber/Vol2/Images/Table4_2a.jpg
http://lib.ucr.edu/agnic/webber/Vol2/Images/Table4_2b.jpg