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Bromeliad Pollination and Hybridisation

 

By Gerry Stansfield

In my first article I talked about collecting brom seed and what to look for, i.e. what do the seed of the various genera look like? In this article I will talk about pollination because, alas, the great majority of bromeliads do not self pollinate and many will not accept their own pollen and so require our intervention to assist in the pollination process. Some bromeliads receive help from other sources, such as birds (the Humming bird is a great pollinator in the bromeliads' homeland of South America). In New Zealand it is possible with small fantails and yellow eyes but mostly it is bees and especially the bumblebee. Moths also play an important role in this process. Many large vrieseas like hieroglyphica, platynema, fosteriana etc open their flowers at night for the moths to do their work and then close again in the early morning. We must remember that it's not good to leave it up to outside intervention as contamination is possible and we would have no idea what it was crossed with. So, if we do it, it's best to know what we are doing and tag or name the crosses.

Why should we pollinate?

Firstly, if we are to expand our collection without spending a lot of money, then growing from seed is the answer, and to get seed we (or someone) must pollinate the plants. You know we have a seed bank in the Society and we receive seed from New Zealand and from around the world.

This keeps us up with a large number of species of bromeliads one can grow. Another difficulty we have to contend with is that many bromeliads will not accept their own pollen so we must have a number of the same plants so we can cross pollinate from one to another e.g. Aechmea fasciata will not pollinate from its own flowers and you will need two plants, or even better, three, where you can cross the pollen from one plant to another. Now Ae. fasciata is not an easy one to try and there are much easier aechmeas and other bromeliads to play with. Also, it takes about nine months or more for the seed to ripen so it's a long wait before you can tell if you have been successful. The second reason for learning how to carry out pollination is so that we can hybridize. Mulford Foster, recognized as the great 'guru' of bromeliads, once said, "Hybridizing bromeliads is like changing an already beautiful plant into something exquisitely outstanding'', and if we look at some of the wonderful hybrids of today we can say "how right Mulford Foster was.''

The first principle of pollination is to understand the different parts of the flowers. In following illustrations we can see that there are two types of flowers in the Bromeliaceae family. In type A the ovary chamber is outside the flower and at the base of the stigma. All plants in the sub-family 3 Bromelioideae have this feature and it is known as having 'Inferior Ovaries.' In type B the ovary chamber is inside the flower but also at the base of the stigma and this refers to all the plants in the sub-families 1 and 2, being Pitcairnioideae and Tillandsioideae. These plants are known as having 'Superior Ovaries.'All bromeliad flowers have three sepals, three petals, six pollen stamens and one pistil and stigma.

Before we attempt the pollination process there are a number of things we need to help us. A magnifying lens head piece is much easier to use than a hand held one and frees our hands to do other things. You will need a long steel or alloy pointer, about 15cm long, say an old knitting needle, and you will also need a pair of long tweezers and some folded tissues, to transfer the pollen from one plant to the other. Before pollination is carried out you must determine the time of day when the flowers are fully open and that the pistil and pollen stamens are fully receptive. Perhaps this is the difficult part, as we have nothing to tell us when that may be except a change in the pistil that will allow the pollen to stick to it. So timing is an important factor in knowing when to pollinate. Large vrieseas like hieroglyphica, platynema, gigantea etc will have opened in the night waiting for the moths and you must pollinate them early, say around 7.00am, or the flowers could be lost by 9.00am or 10.00am. I find that neos. and nids. are best pollinated around 9.00am. On cold days all this will change, so you must observe your plants and be ready.

The procedure is no different to other flowers except that with bromeliads you must emasculate (or remove) the pollen stamens from the plant you want to pollinate to guard against contamination. It will now be called the seed plant or mother plant. This can be easy on some plants but on neos. and nids. it can be difficult and is best done in the early morning before the pollen and stigma are receptive. Using the steel needle and the tweezers, open up the three sepals. You will find that this allows the three petals to open up which pulls the pollen stamens away from the stigma. You can then pinch out the pollen stamens with the tweezers. Your seed mother plant is now ready to receive pollen from your other plant in the case of two Neo.carolinae or two Aechmea fasciata etc. The pollen stamens should be pinched off with the tweezers and the pollen scraped off and placed on to the stigma of the seed mother plant.

You should remember that in the case of flower heads submerged in water e.g. neoregelias and nidulariums, the water must be taken out the day before so as not to wet the pollen. I use a small plastic tubing with a Vet's syringe. If you tip the plant up you will empty all the water and that is not good for it so, just suck that water out to below the flower head. You can also use a cooking basting syringe.

After saying that many bromeliad plants will not self pollinate, and that they will not accept their own pollen, it has to be said that there are a number that do. All or most vrieseas, tillandsias and guzmanias can be pollinated with their own pollen, so there's no need to strip the pollen stamens, unless you're going to hybridize. With the tweezers, cut off a pollen stamen and wipe it on the stigma, noting that there is a nice little mound of pollen on the stigmatic surface.

The most important part...NAMING!

With all bromeliads I use a small piece of plastic slim line Venetian blind, say 50mm long x 5mm wide, with one end cut to a taper. I use a code (as there isn't much room) so it could be VR pl x Ft which could mean Vr platynema variegata x Vr fosteriana (rubra). All of this you will have written into your bromeliad pollination handbook. Remember, it's your plant so you can call it whatever you like as a code e.g. Vr, 631. Push the little code tag into the sepals at the back of the flower where it will stay until the flower sets seed and is ripe. In the case of neos. and nids. you can mark the flower and the next day you will find that it has sunken and this will allow you to place a piece of large drinking straw (milk shake type) over the whole flower and ovary. Remember to code the straw!

HYBRIDIZATION

Up to this point I have been talking about pollinating species. In the case of hybrids the procedure is no different. You MUST emasculate the pollen from the seed plant to avoid contamination and then proceed to take the pollen from another plant and very carefully place it on to the stigmatic surface of the seed plant. If you cross two species of the same i.e. two Neo carolinaes, then you will only get another carolinae species. If you cross two different species, say Neo. carolinae x Neo. marmorata, you will get an F1 hybrid, and each of the seedlings will have consistent characteristics – in other words, they will be a mixture of both parents. However, if you cross two F1 hybrids you will produce an F3 hybrid but with inconsistent characteristics. Most modern day hybrids have two or more parents and crossing these will produce some interesting results e.g. should you cross Neo.Catherine Wilson with, say, Neo.Lambert's Pride as I have done, you will find some very lovely new hybrids, as with some of the Skotak hybrids that have four or five parents. Good luck and next time I will talk about seed raising.

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