Scytonema
Scytonema spp. · Algae
Out of the water · Photo: Becky Dill / CC0
Also called Brown felt, Black crust, Blue green algae, Scytonema spp.
May produce toxins
Only a lab test shows whether a bloom is toxic. Keep people, pets and livestock out of discolored or scummy water until it is tested.
How to identify Scytonema
- Dark brown to black felt or turf on wet rocks, wood and soil
- Feels woolly and dries to a dark crisp film
- Brownish yellow color from a sun protecting pigment in the sheaths
- Paired false branches visible under a microscope
Similar species
Star jelly is rubbery jelly, not felt; Calothrix is a thinner, harder crust.
Growth profile
| Season | Present year round, growing when wet and going dormant when dry. |
|---|---|
| Starts | Wet, mild weather |
| Light | Full sun tolerant |
| Depth | Wet surfaces at and above the waterline |
| How it spreads or reproduces | Fragments carried by water and foot traffic |
| Habitat | Seeps, spring outflows, wet cliffs, shorelines above the waterline and shallow pond edges. |
Why it matters in a lake
Mostly found on wet rocks and seeps rather than in open water. It fixes nitrogen and is usually harmless.
Where it is found
- Idaho: Rare
- Oregon: Rare
- Wyoming: Rare
Classification
| Kingdom | Bacteria |
|---|---|
| Phylum | Cyanobacteria |
| Class | Cyanophyceae |
| Order | Nostocales |
| Family | Scytonemataceae |
| Scientific name | Scytonema spp. |
More benthic cyanobacteria
Lyngbya
Oscillatoria
Phormidium
Calothrix
Tolypothrix
SpirogyraNeed a hand?
Worried about a bloom?
We identify algae under the microscope and test for cyanotoxins, so you know what is in the water and whether it is safe.
Idaho / Wyoming (208) 501-4531Oregon (541) 280-0596