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leocarpus fragilis

Class: Myxomycetes, subclass Myxogastromycetidae
Order: Physarales
Family: Physaraceae

Revisiting a local myxomycete

Every winter for the last few years, a colony of the slime mold leocarpus fragilis has fruited a few weeks after the winter solstice. After several years, I managed to start taking decent photographs of it.

January 2004

In January of 2004 it fruited twice, and I finally got some decent pictures of it.

First appearance

When the colony first appeared, I caught it before it developed sporangia. The viscid, nodular mass in the following photo envelops two pine needles.

A few threads extended from the colony across the tree bark.

Within a day the threads had disappeared and the sporangia had sprouted and withered. I didn’t expect to see the slime mold again until the following winter. Nevertheless, I prepared by asking a friend for a short lesson on macro photography—next time I was going to get some good pictures! I’m glad I didn’t put the lesson off, for the colony reappeared less than a week later.

Second appearance

I almost didn’t notice the colony’s return, as it appeared almost out of sight of my front window. I happened to catch a glimpse while taking out the recycling. Upon seeing it, I borrowed a camera and went to work.

Here’s the main sporangia mass, which was attached to bark at the tree’s base. Note the membranous attachment of sporangia visible center right.

Twenty hours later

By the next morning, the sporangia were darkening and one at the bottom had collapsed. Note in particular the ones in the upper right of the image below.

Sporangia attached to an adjacent needle had almost completely dried up, as these before and after photographs show.

The weather preceding the appearance of the slime mold was cloudy, cool, and rainy. There hadn’t been freezing temperatures for several weeks. To date, the colony has always appeared within an area of about a square yard or two, on either a bed of pine needles, an old and wet piece of wood, or the base of a pine tree. It usually lasts several days. In January 2004 it appeared and lasted two days, then reappeared a week later.

December 2004

The slime mold fruited again in the middle of December. Here are four moments in its development over the course of twenty-seven hours.

2004-12-16, 2:15 PM: undifferentiated mass

2004-12-16, 6:42 PM: sporangia forming

2004-12-17, 8:52 AM: sporangia fully formed

2004-12-17, 5:16 PM: aging sporangia
(note polygonal ridges on center sporangia)

The site was disturbed in 2006, and a large, rotting piece of wood was removed. I didn’t see the slime mold fruit that year, and wondered whether it had lost a source of nutrition.

February 2008

The slime mold fruited profusely in the middle of February 2008, on the first cloudy day after a week of sunny weather with temperate days and cold nights.

2008-02-19, 12:30 PM

 

A few days later a new fruiting appeared. I saw it early enough to get a picture of early differentiation:

2008-02-25, 11:30 AM

 

This slime mold tends to first appear at the base of trees, on the north side. Could the lack of light there affect when they appear? Or is it simply coincidence that they appear around the time of the winter solstice? Could their food supply be drying up due to low light levels?

I hope in future to catch it when it’s starting to congregate. Time-lapse photography could be interesting, too...

Notes

• Images on this page are scaled by a factor of 8-10×, full-size images approximately 20×. [Actual size: .] A typical sporangium is approximately 2mm long.

• My thanks to Lars & Paul, for the loan of a camera and macro photography tips.

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