The small white flowers of sticky asphodel may be pollinated by small flies. (Courtesy Photo / Bob Armstrong)

The small white flowers of sticky asphodel may be pollinated by small flies. (Courtesy Photo / Bob Armstrong)

On the Trails: A not at all mythical sticky situation

A pretty little perennial plant, sometimes called sticky asphodel, grows in many of our muskegs.

By Mary F. Willson

A pretty little perennial plant (Triantha glutinosa) grows in many of our muskegs. It’s sometimes called sticky asphodel, after the flowers that were said to grow in the Elysian Fields where the souls of the dead resided. The basis for this name-transfer from the myth to a tangible organism is not clear; I presume the original name-giver had not actually visited those mythical fields…

The stem of sticky asphodel earns its name by capturing tiny flies, which will be digested. (Courtesy Photo / Bob Armstrong)

The stem of sticky asphodel earns its name by capturing tiny flies, which will be digested. (Courtesy Photo / Bob Armstrong)

It bears white flowers on a sticky stem that often catches small insects. Sometimes ten or twenty tiny insects are stuck to a stem, all of them less than two millimeters long and most of them less than one millimeter long. This observation led to questions: is this plant maybe insectivorous, like the sundews, or do the sticky hairs somehow protect the flowering stem from herbivores? My colleague and I sometimes observed geometrid moth caterpillars on these plants, where they eat the seeds out of the seed capsules. But the caterpillars are not deterred by the sticky hairs; when experimentally placed on a sticky stem, they usually marched right up to the seed capsules. So those hairs did not defend against that herbivore, at least.

Geometrid Caterpillar on False Asphodel.wmv from Bob Armstrong on Vimeo.

Could the sticky hairs perhaps digest the captured insects and thus gain nutrition for the plants? We labelled some fruit flies with an isotope of nitrogen and, in 2007, placed them on the stems while the plants were flowering. Weeks later, when the seeds matured, we looked for that isotope label in the seeds and in the roots — two places where nitrogen might be stored, either for the offspring or for future growth. But no isotope marker showed up there. In contrast, sundews happily took up the extra nitrogen from our fruit flies. We then, for various reasons, abandoned the project.

[On the Trails: Taking in the scenery on another level]

However, just recently — in 2021 — there came a fascinating published report that a closely related species (T. occidentalis) is indeed insectivorous. This species is so closely related to our local T. glutinosa, that it is likely that the findings of this study would apply here as well.

The researchers in that study applied isotopically labelled fruit flies to the flowering stems. Sampling the developing fruits, leaves, and stems a week or two later, they found the isotope marker in all those plant parts, indicating that nitrogen had been transferred from insect to plant. This resulted in an increase of nitrogen concentration, particularly in fruits and stems, but that increase was temporary. Apparently that nitrogen had been translocated, perhaps to roots (for future growth) or possibly to maturation of additional fruits that year. These possibilities were not measured, at least in this report.

A moth larva called a looper investigates sticky asphodel capsules and will later eat the seeds. (Mary F. Willson / For the Juneau Empire)

A moth larva called a looper investigates sticky asphodel capsules and will later eat the seeds. (Mary F. Willson / For the Juneau Empire)

However, as noted above, our little study did not find the marker isotope in roots or seeds. So we can hope that further research will resolve this issue.

Nevertheless, the new research clearly shows that, assuming our species is like the other, we have another local member of the insectivorous-plant clan, along with two species of sundew, bladderwort, and butterwort. I’m sure that more will be discovered, if we would just look!

Back in the 1980s, one of my PhD students showed that labelled nitrogen was taken up in sticky traps on the inflorescences of Penstemon digitalis and Cirsium discolor. In P. digitalis, sticky hairs occur on the flower itself and its stem; in C. discolor, the traps are on the outer involucral bracts just below the flowering head. The pollinators of penstemon (bees) are too big to get stuck on the traps, and the assorted pollinators of Cirsium approach the flowers from above, and so do not encounter the traps. No defensive function of those traps was found. Instead, the sticky traps had digestive enzymes and provided extra nitrogen and phosphorus to the plants, and this resulted in increased numbers of seeds by both species. Unlike most species that are known to be insectivorous, these two do not inhabit very nutrient-poor habitats such as bogs.

• Mary F. Willson is a retired professor of ecology. “On the Trails” appears every Wednesday in the Juneau Empire.

More in News

(Juneau Empire file photo)
Aurora forecast through the week of Dec. 29

These forecasts are courtesy of the University of Alaska Fairbanks’ Geophysical Institute… Continue reading

Commercial fishing boats are lined up at the dock at Seward’s harbor on June 22, 2024. A legislative task force has come up with preliminary recommendations to help the ailing Alaska seafood industry. (Yereth Rosen/Alaska Beacon)
Legislative task force offers possible actions to rescue troubled Alaska seafood industry

Boosting international marketing, developing new products, more support for workers, other steps.

Rep. Sara Hannan (left) and Rep. Andi Story, both Juneau Democrats, talk during a break in floor debate Sunday, May 12, 2024, at the Alaska State Capitol. (Mark Sabbatini / Juneau Empire file photo)
Bans on cellphones for students, abortion, styrofoam food containers among Legislature’s first prefiled bills

Two members of Juneau’s delegation reintroduce bills for students, public employees, crime victims.

A combined crew from the Yakutat City and Borough and Tongass National Forest began pilot treatment of willows to improve moose browsing habitat in August of 2023. (U.S. Forest Service photo)
Tongass Forest Plan Revision draft released, starting clock on 45-day comment period

Plan seeks to balance range of tribal, environmental, industrial and climate goals.

Students arrive at Thunder Mountain Middle School on Aug. 15, 2024. (Laurie Craig / Juneau Empire file photo)
Juneau School District not impacted by nationwide PowerSchool data breach

The Juneau School District was notified on Friday by PowerSchool, the company… Continue reading

An aerial view of downtown Juneau. (Clarise Larson / Juneau Empire file photo)
Juneau Affordable Housing Fund approves two apartment projects

Guidelines have been refined since Ridgeview sold at market price.

Kids take part in ski lessons this week at Eaglecrest Ski Area. (Eaglecrest Ski Area photo)
Eaglecrest’s new GM: “Something drastic needs to happen or that team is going to crumble from the inside”

Employees’ struggles acknowledged as leaders responding to critical report say future holds promise.

(Michael Penn / Juneau Empire file photo)
Police calls for Wednesday, Jan. 8, 2024

This report contains public information from law enforcement and public safety agencies.

A small studio apartment in The Assembly Apartments overlooking downtown Juneau. (Laurie Craig / Juneau Empire)
Assembly Apartments that provided Depression-era jobs now the latest in government housing

Historic building next to Alaska State Capitol awaits arriving legislators and staff.

Most Read