We have several Dactylorhiza species starting to come into flower at the nursery and I would like to be able to save seed from the Southern marsh (D praetermissa) and Northern marsh (D purpurella). But the marsh orchids are promiscuous and if I leave them to their own devices they will cross with each other and the Common spotted and the Heath spotted, which will all be flowering at the same time. So I have made a couple of isolation tents using shade netting (they all appreciate a little shade anyway on a hot day) and I will be hand pollinating the plants in the tents.
It’s a delicate task using a cocktail stick. Orchid pollen is not the usual powdery yellow stuff that most plants produce. The orchid flower needs to make thousands of seeds per seed pod and each seed comes from a different pollen grain meeting one of the thousands of ovules produced by the recipient flower. So the pollen comes as a clump of pollen grains on a stick ready to be transferred to another flower all in one shot. These are called pollinia and they are concealed in a pocket behind the anther cap.
If you give the pollinia a little poke, they will jump out and stick themselves to your cocktail stick like little antlers, about 1mm long. They do this when a bee or other pollinator sticks their head in the flower. The bees comes out with mini antlers and a ball of yellow or green pollen on the end and then the bee transfers it to the stigma on the next flower. This is what you mimic with your cocktail stick. Next time you’re in a wildflower meadow with orchids in flower, look closely at the bees, you will sometimes see yellow blobs stuck to their heads.
I have started doing this with the Northern marsh orchids, which have a few flowers open, and I will go back and do some more as more flowers open up. I will do the same with the Southern marsh orchids in the next door tent, always using a clean cocktail stick.
As long as I can keep the pollinators out, I can be sure that my seed will be true to the species and not hybridised. Many orchid growers deliberately hybridise their plants to produce new variations and to produce bigger, brighter plants with hybrid vigour, but for now I am going to try to keep to native species rather than hybrids.