Phenology Report: John finally discovers the elusive female sweet-fern flower

By Charlie Mitchell

Published May 17, 2024 at 12:00 PM CDT

A close-up shot shows the foliage of a sweet-fern in Orr, Minnesota on Aug. 13, 2022.

KAXE Staff Phenologist John Latimer provides his weekly assessment of nature in Northern Minnesota. This is the week of May 14, 2024.

During his phenology report this week, staff phenologist John Latimer called our attention to a small nondescript plant found along roadways and in sandy soils: the sweet-fern.

Not a fern at all, the sweet-fern is actually a woody plant that reproduces with seeds (ferns are non-woody and have spores, not seeds). This little plant has fascinated John for years! With its sweet aroma and penchant for growing in poor soils, it’s a familiar friend to those who pay attention to such small, easily overlooked plants.

A photo of a sweet-fern in bloom shows its male and female flowers. The male flowers are large, long, and yellow-green with scales resembling a pine cone. The female flowers are smaller, bristly, and bright red. They sprout from the stem beneath the male flowers. This image was taken on April 28, 2023 in Porter, Maine. — A photo of a sweet-fern in bloom shows its male and female flowers. The male flowers are large, long, and yellow-green with scales resembling a pine cone. The female flowers, when fully developed, are smaller, bristly, and bright red - this is what John Latimer was looking for. This image was taken on April 28, 2023 in Porter, Maine.

The search

Since first noticing the sweet-fern, John was on the hunt to see its flowers. He found the male flowers quite easily: in spring, before the foliage comes out, the reddish-yellow male flowers give the plant a rusty color. John found these, flicked them with a finger, and watched a cloud of pollen fly out from the dangling flower.

Where there’s pollen, there must be female flowers, so he hunted for female plants next. According to the illustrations John had seen, he was looking for plants with a bristly red structure. Despite a hands-and-knees search over 500 square feet, he couldn’t find a single one!

Defeated, he went home to consult his books again. Welby R. Smith’s book, Trees and Shrubs of Minnesota, directed him to look right underneath the male flower. The sweet-fern is monoecious: both male and female flowers will grow on the same plant.

A sweet-fern is shown just before bloom in Grand Rapids, Minnesota, on May 14, 2024. The male flowers have emerged and begun dispersing pollen: these are the long, reddish-yellow catkins at the end of the stem. The female flower has not yet emerged - its bud is the pine-cone like structure with fine white markings, located just behind the male flowers. — A sweet-fern is shown just before bloom. The male flowers are the long, reddish-yellow catkins at the end of the stem. The female flower has not yet emerged - its bud is the pine-cone like structure with fine white markings, located just behind the male flowers.

Back he went to the stand of sweet-fern to look again. To his surprise, he found he had missed seeing the tiny, 1/16-inch female flower bud nestled just under the male flower. The female flowers hadn’t developed yet, despite all the pollen blowing in the breeze – so, looking for those red bristly structures was a task doomed to failure! In a week or two, however, he might have more luck.

Despite the lack of fully-developed female flowers, John was still able to locate the buds where the flowers will emerge. These small, pine-cone like buds had small white markings and were quite different from the larger, pollen-bearing flowers.

You can learn more about this enigmatic little plant in John’s report – he details how it got its scientific and common names and how to use it to create an anti-itch salve.

Topics

Intro (0:00-0:25)
Spring ephemerals and other flowers (0:25-8:49, 13:03-13:13, 16:09-22:42)
Location matters for phenology (3:09-3:35)
The futility of picking marsh marigolds (3:36-4:40)
The odd reproductive habits of Juneberries (5:38-7:36)
Is your plum American or Canadian? (7:36-8:49)
Early colors of the forest overstory (8:49-10:31)
Seeding process of aspen trees (10:31-11:40)
Unfurling ferns and horsetails (11:40-13:03, 14:25-15:32)
Insects of interest (13:13-14:25)
A bounty of birds and the joys of Merlin Bird ID (15:32-16:09)
The fern that’s not a fern – sweet fern (17:53-22:42)
Conclusion (22:42-23:31)

That does it for this week! For more phenology, subscribe to our Season Watch Newsletter or visit the Season Watch Facebook page.

Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).