Wednesday, May 18, 2022

March of the Mayapples

A colony of mayapples, Podophyllum peltatum.












They’re relentless, these mayapples.

Over many years, five plants became ten, then twenty, then fifty. As their numbers increase, young plants at the boundary of the patch run head-long into ostrich ferns and wild ginger, themselves trying to gain new ground. The outcome of their competition is uncertain, but their shared imperative is clear: Advance.  

Mayapples do this using rhizomes (RY-zomes), underground stems that grow more or less horizontally and produce roots and shoots along their lengths. In ideal conditions, mayapple rhizomes grow rapidly – up to 20 centimeters, or 8 inches, per year (1).

A mayapple rhizome is a horizontal, underground stem. Roots and shoots
develop along its length.

If a colony begins with a single seed and if it successfully grows and reproduces this way, the result is a patch of genetically identical individuals – clones, in other words. In ecological terms, the clones are called ramets, and the genetically distinct population they belong to is a genet.

In a favorable and stable habitat, reproduction by rhizomes is an advantage. If their genes are suitable for where they’re growing, ramets produce mature plants faster than seeds. They’re also less expensive. Compared to flowers and fruits, they demand less of a plant’s energy to create.

If the environment or habitat changes, however, a colony of clones may not have the right genes to adapt and survive. If they’re all the same, they would respond similarly to a shift in some variable, such as temperature. If the change is more than they can handle, the genet may not survive.

That’s why variety is important. Mixing genes, such as by cross-pollination between genetically different plants, produces new and possibly better, more adaptive, combinations. Reshuffling the genetic deck can be an advantage, so mayapples also produce flowers.

That big-budget task falls to the older ramets. Unlike younger plants, they have two umbrella-shaped leaves instead of one, and between them grows a single, white, bowl-shaped flower that blooms in mid to late spring. It takes some effort and good timing to see it.  Although it’s an inch or two across and somewhat showy, it’s below the leaves and nodding, and it’s spent in a couple of weeks.

Mature mayapple ramets produce a single, white,
nodding flower. 

The flowers produce no nectar, but bumblebees and other insects visit them to collect pollen (2). Without pollinators mayapples won’t produce seeds, because they’re mostly self-incompatible – they can’t pollinate themselves, as some plants do if cross-pollination isn’t successful (3).

It’s puzzling, then, that mayapples don’t make nectar. A sugary sip is a sure draw. It’s another expense, though, and mayapple’s budget seemingly doesn’t cover it. Instead, the plants may rely on other species to provide the bait. For example, one study found that mayapple colonies close to nectar-producing lousewort (Pedularis canadensis) were visited by pollinators more often. Because it flowers at the same time, lousewort acted like a magnet, drawing pollinators that would then more frequently visit a mayapple patch (4).

When fruits are ripe, another challenge arises: What will disperse the seeds? Box turtles, deer and raccoons are among the animals that eat the fruits (5, 6). They will deposit the seeds in their feces, but that’s not always the end of the story. White-footed mice and chipmunks have been observed picking mayapple seeds out of raccoon dung to eat or cache, and rainwater may also usher the seeds out of the muck and onto new ground (6).  

If the seeds end up in a favorable spot and if conditions are right for germination, mayapple seedlings emerge. They begin another genet, a new colony, with an old and familiar habit. The march of the mayapples resumes.

How to Identify Mayapple

Mayapple’s scientific name, Podophyllum peltatum, describes the plant’s appearance. Podophyllum comes from Greek words meaning “foot leaf,” referring to the foot-like shape of the leaf lobes. The name peltatum refers to the plant’s peltate leaves. They are attached to their petioles at the center of the blades, like an umbrella or a shield.

For more photographs and tips to identify mayapple, see the Minnesota Wildflowers page for this species.

Caution

Mayapples are hazardous. Except for ripe fruits, all parts contain harmful concentrations of podophyllotoxin, a potent compound that can be absorbed through the skin and digestive tract. Plants are most poisonous when they are flowering.  See Colorado State University’s Guide to Poisonous Plants for more information.

 

References

(1) eFloras (2022). Published on the Internet http://www.efloras.org [accessed 13 May 2022]. Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.

The eFloras page for mayapple is here

(2) Mahr, S. Mayapple, Podophyllum peltatum. Wisconsin Horticulture, Division of Extension, University of Wisconsin-Madison. Accessed May 17, 2022 at https://hort.extension.wisc.edu/articles/mayapple-podophyllum-peltatum/.

(3) Whisler, SL, and Snow, AA. 1992. Potential for the loss of self-incompatability in pollen-limited populations of mayapple (Podophyllum peltatum). American Journal of Botany 79 (11): 1273-1278. https://doi.org/10.2307/2445055; https://www.jstor.org/stable/2445055.

(4) Laverty, TM. (1992). Plant interactions for pollinator visits: a test of the magnet species effect. Oecologia 89 (4): 502-508. https://doi.org/10.1007/BF00317156, https://www.jstor.org/stable/4219917.  

(5) Rust RW and Roth RR. 1981. Seed production and seedling establishment in the Mayapple, Podopyllum peltatum L. The American Midland Naturalist 105 (1): 51-60. https://doi.org/10.2307/2425009; https://www.jstor.org/stable/2425009.

(6) Niederhauser EC and Matlack G. 2017. Secondary dispersal of forest herb seeds from raccoon dung: contrasting service by multiple vectors. Plant Ecology 218 (2): 1135-1147. https://doi.org/10.1007/s11258-017-0748-4.

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