Trailing Arbutus [Epigaea repens]

Trailing Arbutus [Epigeae repens]

Sweat Bee [Lasioglossum Dialistus] pollinating Trailing Arbutus [Epigaea repens]. Dauphin County, Pa. 4-17-25

Trailing Arbutus [Epigaea repens]. Dauphin County, Pa. 4-17-25

Bee Fly [Bombylius major] searching for nectar and pollinating Trailing Arbutus [Epigaea repens]. Dauphin County, Pa. 4-17-25

Bee Fly [Bombylius major] searching for nectar and inadvertently pollinating Trailing Arbutus [Epigaea repens]. Dauphin County, Pa. 4-17-25

Trailing Arbutus [Epigaea repens]. Most flowers of this species are unisex, meaning they are male or female. This flower is a female, showing the five pointed star of the female structure open and waiting to receive pollen. Dauphin County, Pa. 4-17-25 [above&below]

Trailing Arbutus [Epigaea repens] next years flower buds. Dauphin County, Pa. 9-19-24

Mushroom and Trailing Arbutus [Epigaea repens]. Dauphin County, Pa. 8-27-24

Trailing Arbutus [Epigaea repens].The outer sheath of the seed berry has been completely removed to reveal the seed berry looking like a white strawberry covered in seeds. Notice the seed berry is in five sections, the sheath in 5 sections, a five pointed star female apparatus for receiving pollen and earlier still 5 petals to the flower. Remembering that this flower was a female as each individual colony of plants observed was either male or female. Of all the many colonies of plants seen and hundreds of flowers observed only 4 female plants [all in the same group] produced a seed berry. It would seem that successful pollination is poor at best for this plant and one must wonder, with this not too successful pollination, just how old these individual colonies of Trailing Arbutus can be.

This is just but one of the tiny seeds from Trailing Arbutus [Epigaea repens] as seen on a leaf of Trailing Arbutus. Dauphin County, Pa. 6-20-24

After seeing this particular flower of Trailing Arbutus [Epigaea repens] being pollinated on April 14 by a Bee Fly [Bombylius major], 68 days later the seed berry is drying out and peeling back to reveal the tiny seeds. The seeds are affixed to berry by a sticky substance. 2 days after this picture was taken the berry was completely exposed the seeds dried out and the berry had fallen with the seeds being dispersed. I believe that ants do play an important role in seed dispersal as is the case with many plants and their seeds.

The new foliage of Trailing Arbutus [Epigeae repens]. Dauphin County, Pa. 5-19-24

The new foliage of Trailing Arbutus just starting to make an appearance [Epigeae repens]. Dauphin County, Pa. 4-23-24

Bee Fly [Bombylius major], drinking nectar and in the act pollinating Trailing Arbutus [Epigaea repens]. Dauphin County, Pa. 4-14-24

Although it is possible for the flowers of Trailing Arbutus [Epigaea repens] to be a perfect flower [having both male and female parts] most are unisex, having either male of female parts. In fact most groups of plants and their flowers are one sex or another. Pictured below is the female with its star shaped apparatus that is open and ready to receive pollen, pictured above is the male with its pollen producing structures. The amazing world of just one tiny spring flower and its fascinating strategy for reproducing.

The one thing that I was determined to see and learn about this spring was the pollination of Trailing Arbutus [ Epigaea repens]. I have spent many years trying to observe the pollination and unlocking the mystery of this one tiny, beautiful and at times hidden from view, flower, and for me the harbinger of spring. First starting to open in picture 1 on April 10, although it is possible for flowers to be a pefect flower [containing both male and female structures] most flowers are unisex [having either male or female structures], in picture 2 you can see the five pointed star of the female structure waiting to receive pollen. It clearly seems that most groups of plants are really just one plant as all the flowers in that particular group are one sex. On April 14 after waiting for several hours, staking out a particular group of flowers, I was startled to see a bee, picture 3, fly over my head and hovered at each flower dipping its proboscis deep into each flower. After all these years could this finally be the pollinator that I have been waiting to see, it was! It turned out to be a Bee Fly [Bombylius major]. I observed the Bee Fly, a beautiful insect that I have never seen before, visiting each of the flowers [a group of 12] in front of me on three different occasions in three hours. On May 16 [picture 4] for the first time I found a seed berry on one of the same flowers visited by the Bee Fly a month before. It turned out that of the hundreds of flowers seen only a total of 5 berries were found, 3 of which were found on the flowers where the Bee Fly had been observed. It would seem that successful pollination is at best very sporadic for this flower. The thrill and excitement of seeing the Bee Fly on Trailing Arbutus after so many years trying was beyond description and there is nothing that I would rather do than spend my time on the mountain, just quietly observing, and trying to unlock one of nature's many mysteries.