THE PERFECT FLOWER (SOUTHERN MAGNOLIA)
To celebrate the end of our first season as a podcast, we’re talking about a blooming beauty with a perfect flower, the Southern magnolia (Magnolia grandiflora). Mr. Bean beetles, ancient sex organs, and one intelligent flower that knows how to get it done. Then we play a fun game about ancient Greek gods and answer a listener question. See you next season!
Southern Magnolia
(Magnolia grandiflora)
What makes southern magnolias so interesting? This is the question that I have been thinking on lately, and the answer (or perhaps answers) I think need some context and a subject to work with. The subject in this case is the southern magnolia (Magnolia grandiflora) of southeastern North America. This tree is a fabulous centerpiece to arrange my arguments around because it just does itself so, well, grandly.
The southern magnolia is a classic forest tree of the south, and has quickly become a classic street tree across the United States. The fragrant white flowers and large, leathery evergreen leaves make it a showy and tough tree year-round. But its merits as a landscape tree are not what elevates it, or any other magnolia for that matter, to such high standing. It just happens to also be a showoff. What makes this tree so fabulous is the sheer perfection of its flowers coupled with their laudable antiquity, and capped off by their diabolical co-opting of their best friends: silly beetles.
Labeling the flowers of the southern magnolia as ‘sheer perfection’ is a bit of a put-on. It’s obvious to anyone that looks that they are quite beautiful. The Latin epithet grandiflora, though it means literally ‘big flower’, is an apt description in the modern sense, too: they are grandiose, flamboyant, and fragrant flowers, surely due their compliments. But botanically speaking, perfection has another meaning. A perfect flower is one that has both the female and male sexual parts in the same flower, the pistils and stamens, respectively. Though not rare in the plant world, it does make for some spectacularly full floral displays.
Perfection, however, comes at a cost. With both sexual parts in the same flower, self-pollination is a problem to be dealt with. Plants, not unlike most other life on the planet, tend to be healthier and more vigorous when their genes come from unrelated parents. Self-pollination is something few plants can tolerate, and thus most have developed schemes to avoid it. The southern magnolia chose an undeniably ingenious way to keep self-pollination to a minimum, and it did so by befriending beetles.
Beetles, as insects go, are another ancient lineage. Beetles were around long before flies, ants, and bees evolved. So when the first flowering plants came along and started reaching across the aisle to work with insects for pollination, beetles were who they found. Beetles and magnolias entered into a relationship that benefited both parties, but it would become clear that the magnolia was the party that was pulling the strings. You see, the flowers of the southern magnolia go through a transformation and may keep the beetle prisoner while they do it.
In order to avoid self-pollination, when the magnolia flowers initially open up, only the stamens are active with pollen at the ready. In order for pollen to successfully transfer to the pistil, the pistil needs to be moist so that the pollen grain sticks and can burrow down through the style to find and fertilize the egg. A dry pistil cannot be pollinated.
So, when the beetles are visiting, only half the reproduction system is active, successfully avoiding self-pollination. The magnolia’s next trick is what captures the beetles: the flower closes after the first opening, and any beetles lounging away inside are caught. During this time, the stamens drop away, and the pistil begins to moisten. The flower opens back up, and a newly free beetle flies away to find another flower, now covered in pollen. If this flower is receptive to pollen, the deed is done.
This relationship is at once sublime in its cleverness and rudimentary in its clunkiness. Like some curious, ancient mechanism found in some long-lost ruin, it works beautifully, was way ahead of its time, and is positively charming in light of how far technology has advanced since. I think this is what makes the southern magnolia so interesting. Though at the surface its showy, gaudy flowers and high-gloss leaves lead one to believe it is a simple fancy plant, it’s the deftness with which the tree plays its cards that elevates it beyond the fray.
Completely Arbortrary is produced and hosted by Casey Clapp and Alex Crowson
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Cover art by Jillian Barthold
Music by Aves and The Mini-Vandals
Episode cover photo by DavetheMage
Additional Reading:
The Southern Magnolia (Magnolia grandiflora)
Magnolia flower in action
Magnolia evolution