Sometimes, I’m forced to stretch the limits of the "Plant of the Week" column to include some interesting organisms not quite meeting all the requisites necessary to be considered a plant.

Dog vomit slime mold, Fuligo septica, is one of these.   There are more than 700 species of slime mold known, with this one of the most common.

Slime molds are most often seen growing on top of the mulch in shrub beds where they can indeed look very much like dog puke.  The patch may be 6 to 8 inches across to a couple of feet wide.  The early stage of development is a light yellowish amorphous blob called a plasmodium that slowly expands across the surface of the mulch like a giant amoeba. 

Then as the atmosphere gets drier or hotter, the plasmodium transforms itself into a brownish, cushion-like mass called an aethalia that may be as much as an inch thick and with the consistency of a slice of bread.  As it ages, the tissue begins to break down and liquid, blood-colored droplets form on the surface of the drying aethalia.

This is the spore-producing stage of development.  Instead of producing spores in a distinct body like a mushroom, the entire surface of the aethalia releases millions of wind-and water-borne haploid spores.  The transition from a mushy blob of protoplasm to the release of spores is very fast, usually occurring in 24 hours.

Slime molds are strange but interesting organisms.  The dog vomit slime mold is relatively primitive as slime molds go.  When the haploid spores are released, they migrate to moist, shaded areas where they split open and release a flagellated swimming stage which combines with another haploid spore to form a zygote.

This zygote begins to feed, and the nucleus begins to undergo repeated divisions.  But, unlike most organisms, no new cell walls form, so all of these new nuclei are contained in an ever-expanding mass of protoplasm.   As the environment begins to get drier, the amoeba-like cells join forces and the plasmodium moves to a higher and brighter location for spore production. 

Organisms such as slime molds have caused all sorts of classification problems over the past couple of hundred years.  Linnaeus considered there to be only two kinds of life-plant and animal.

But things just didn’t fit neatly into these two kingdoms, so eventually a five-kingdom model of classification emerged with fungi, algae and bacteria given their own kingdoms.  This system hasn’t worked much better, so now some biologists are supporting adding a sixth kingdom, while others propose stepping back to just three. 

Slime mold is a harmless, but admittedly ugly, thing.  These organisms aid in the breakdown of organic debris and provide another opportunity for the interested gardener to interface with nature. 

If it really bugs you, consider raking the developing plasmodium before it develops or, better yet, just avoid this part of the garden for a couple days.  It will go away by itself.