In this month’s issue of The American Gardener, the membership magazine of The American Horticultural Society, I’ve written a piece about plants that come true from seed – and those that don’t. And, in particular, it set me thinking about pulmonarias.

Many of us know that individual Primula plants have flowers that come in one of two forms: some have “pin” flowers, some have “thrum” flowers. The difference is that in pin flowers, the stigma (which is the female part of the flower where the pollen needs to land) is on a long stalk and so visible in the center of the flower. The anthers, which carry the pollen, are on short stalks low down in the throat of the flower. In thrum flowers, it’s the other way round.

Pollen that a bee picks up on its body from the anthers of a pin flower buried down the tube of the flower is in precisely the right position to pollinate a thrum flower – which has its stigma positioned back down in the tube in exactly the right spot. So when seed is set, the pollen almost always comes from a flower of a different plant. So the seed is the result of hybridization. Who knows where the pollen came from? The only thing that’s almost certain is that the pollen did not come from the plant setting the seed – so the resulting seedlings will be different from the plant that produces the seed.

This is true of primulas - but it’s also true of pulmonarias. You can see it clearly in the pictures at the top. The thrum-eyed American-bred ‘Dark Vader’ (left) with the ring of five anthers clearly visible; and the pin-eyed British-bred ‘Cleeton Red’ (right), with the stigma plain to see, on the right (click to enlarge).

So, the lesson. Pulmonarias tend to shed their seed and often quite a lot of it germinates. But the seedlings are likely to be all hybrids and not identical to the seed parent. So please don’t pass the seedlings to friends with the parent plant ’s name on. If you’d like to pass on the plant, pass on a division.

There's more about a whole range of plants, and whether or not they come true from seed, in the latest issue of The American Gardener. So why not join the American Horticultural Society (Brits can join too) and receive every issue of The American Gardener as well as many other benefits? If you’re already a member, you can read the current issue of The American Gardener, including my article True To Seed, on the AHS website.