Magnolia x soulangeana and a mystery unravelling

Last summer three startling red seed cones appeared on our veteran Magnolia × soulangeana. A 25′ tall inherited tree which we understand was planted over 50 years ago. Sited in an exposed spot at the end of our front garden, late frosts can often leave the Magnolia blossoms as a public embarrassment. Last years long hot summer had left our tree a little drought stressed and some of the leaves were paper thin.

Magnolia October 2014

Magnolia October 2014

Our neighbour who has lived here as long as the tree, tells us she had never seen anything like it. On a visit to Hestercombe in October 2012 we saw a Magnolia covered in productive cones but none the colour of ours last year.

Hestercombe Magnolia Seed Head

Hestercombe Magnolia Seedheads October 4th 2012

Then in October 2014, Sissinghurst Garden blog and Amelia’s A French Garden posted photos of Magnolias with similar seed filled cones to ours. I wondered what had caused our Magnolia at age 50 to start producing. I googled an answer and was left confused by vague lack of pollination reports. The RHS website blurb says ” Magnolias grow readily from seed but may take over 10 years to begin flowering. Collect seedswhen the cones begin to split. Many of the seeds do not fully develop due to lack of pollination.”

This had me thinking how are Magnolias pollinated and was the lack of pollination due to the decline in Bees or is something else afoot?

Our Magnolia in flower April 2013

Our Magnolia x soulangeana in flower April 2013

So I emailed the RHS members advisory service to ask about the pollination of Magnolias and what they thought may have caused ours to finally produce. I had paced out the position of the nearest neighbouring Magnolia and its around 400metres away from ours. Generally they thought the weather conditions – our long hot summer –  and they suggested our tree had reached maturity. I emailed again to clarify the pollination and was intrigued further by their detailed response.

“Our Botanist says magnolia expert Jim Gardiner thinks that although self-pollination (ie by pollen from the same tree) is possible (primarily through the agency of beetles) magnolias are more likely to be pollinated by insects that have visited another tree. They are famously largely pollinated by beetles which are able to find a way into the unopened flowers more easily than bees, flies and other insects. The stigmas are receptive to pollen before the flowers open and quickly become unreceptive on opening. 400m is admittedly quite a large separation, but I do not think it rules out the possibility of cross pollination by another tree.”

It seems timing and ability are key if the stigmas are only receptive for a short time and the shape of the unopened flowers is best suited to beetles and not the bees I had worried about.


Magnolia Seeds

I emailed back one last time to ask if Beetles had been responsible, which species might that be. And again was further intrigued by the response from their Diagnostic Entomologist.

“Although magnolia has flowers that specialise in being pollinated by beetles, it is unlikely that that there is only a single species that does this. Beetles from 9 families have been recorded pollinating magnolia worldwide:

– Cerambycidae (Longhorn beetles, 60 UK species)

– Chrysomelidae (Seed & leaf beetles, 281 UK species)

– Curculionidae (Weevils, 480 UK Species)

– Mordellidae (Tumbling flower beetles, 17 UK species)

– Nitidulidae (Pollen beetles, 91 UK species)

– Oedemeridae (False blister beetles, 10 UK species)

– Scarabaeidae (dung beetles, 83 UK species)

– Scraptiidae (False flower beetles, 16 UK species)

– Staphylinidae (Rove beetles, 1,000 UK species)

It is likely that there are several species from the families above that are responsible for pollinating your magnolia, the exact species will probably depend on both the local beetle fauna and the identity of your magnolia.”

There is so much to learn! If it was a beetle, I know virtually nothing about the local Beetle fauna here but I know I am going to be paying far more attention in future.

Meanwhile as recommended I had cleaned the flesh from the outside of our Magnolia seeds and they’ve been in a small plastic bag with some vermiculite and potting compost at the bottom of our second fridge for the last two months. I shall sow the seed this week, the first time I have ever sown Magnolia seed and let you know if I have any germination success.

27 thoughts on “Magnolia x soulangeana and a mystery unravelling

  1. Your persistence has uncovered lots of interesting facts and it is a story to be continued. I had never thought much of beetles as pollinators but the more you explore the more you learn. Bees get a good press and rarely do damage. Beetles are not so cute and are not everybody’s favourite but it looks like they have a good thing going with Magnolias. Amelia

    • Beetles do seem to have a very poor press. I have just been sent a link by Marian St. Clair to an article on Beetles as pollinators, I have tried to copy the link into my reply to you but I can’t do it, I think you would be interested too Amelia, its on the comments to this post.

    • Hi Marian, Thank you so much for the link to this blogger, I have just read her post and some of the others on her Pollinators blog. There is so much to learn!

    • If I’m successful they’ll be interesting gifts to give away, one Magnolia x soulangeana is enough for me and my exposed garden, I’d really like one thats flowers are more resilient to frost.

    • Thanks Annette, I’m feeling quite hopeful and my family will be pleased the bag of soil is coming out of the fridge, they are not as keen as me on this kind of thing. 🙂

    • Sited in our front garden, we gets lots of comments, usually, ‘what a shame’, as most years the frost gets it,but everyone cheers when the blossom survives and puts on a good show. I hope your neighbours is more sheltered and you get to enjoy the blossom too, It will interesting too Susie to see if that one produces cones with seeds.

  2. I am very impressed with the RHS for giving such detailed answers to your questions. Good luck with the seeds, and I hope you’ll post about any beetles you see on the flowers this spring!

    • I asked 3 times Cathy, each time asking more questions, I did wonder if they were rolling their eyes, but was delighted at their patience and detailed answers. I am going to be very watchful for beetles in the Spring, I hope I’ve got something to post about them too 🙂

  3. Some nice facts there! I’m surprised the RHS didn’t mention that Magnolias are an ancient genus and were the very first flowering plants: they existed well before bees, so needed beetles to pollinate them.
    I know that different types of Magnolias do in fact self-pollinate (given that beetles aren’t as effective as bees), but x soulangeana is a hybrid so probably behaves differently in that regard. Another theory is that ants may act as pollinators to some species Magnolias….

    • Actually, I thought exactly the same thing once Marian St Clair, posted the link to the Pollinators Blog this morning. The process of asking and replying has taken several weeks and had still left me feeling slightly vague. Thank you too for your information, thats interesting about the Ant theory. I should of just asked on here!

  4. You’ve done some very interesting research. I had no idea that Magnolias were fertilized by beetles. We used to have a small Magnolia but it was weakened by a big scale infestation and died.

    • Hi Jason, did you see Marian St.Clair’s link to the Pollinator blog (2nd comment) I think you would be interested to read it, I can’t figure out how to paste that into a reply. Scale is a blooming nuisance, especially if you garden organically, and thats an expensive tree to lose.

  5. I had lots of different magnolias in my last garden and some years I would see these bright red seeds. Once I noticed a seedling in the garden. I watched with excitement as it grew into a small tree and after about 10 years it bloomed. The flowers didn’ t look like any other magnolias in the garden, but I am afraid they were a disappointment, they were very small.
    Good luck with your seeds, you never know what might get. Very exciting.

  6. Julie,

    Was wondering how your Magnolia soulangeana was after last years (2018) drought as I was thinking about planting one. There are a couple of well established specimens in good health very near me but the promise of much hotter summers and more frequent drought gives me cause for concern.
    Many thanks

    • Hi Frank, I moved home a couple of years ago and cannot answer your question but in previous hot summers the leaves dropped early, like you I worry about the effects on our trees with climate change. I am sorry I could not help. Julie

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