Cryptogamic soil or cryptobiotic crust is very fragile and is vital to some prairie plants and soil biota. Cryptogams form a spongy layer that helps protect soil from erosion, absorbs moisture, and provides nitrogen and other nutrients for plant growth. During drought and frost, the cryptogamic crust uplifts and cracks. Cracks in the layer can provide germination sites for seeds from grasses and forbs. Reference: Fact sheet developed and funded by an Eisenhower Grant to the Partnership for Arid Lands Stewardship. Written by: Christine Sandahl.

Cryptogamic soils are fragile, so please avoid walking on them whenever possible..stay on established trails.  Once fragmented by footsteps, mountain bikes, or vehicles, they may take years to recover and are as fragile as tundra lichens.  Crushing the surface layers of the land alters the population dynamics of subterranean organisms and fragments their underground microhabitats.

 Below are photos of cryptogamic soil at Spring Creek  on exposed caliche or limestone.. This cryptogamic crust is the dark bumpy soil prevalent in drier areas of Spring Creek outside the forest and  covers the surface of soil between grasses, shrubs, and flowering plants. This fragile crust is made up of mosses, lichens, algae, and bacteria and a microcosm of other inhabitants such as mites, springtails, nematodes, and other biota.

Also present are jelly fungi (ear fungus) includingAuriculariaspecies – Ear Fungus which has gelatinous fruitbodies contorted into strange shapes like ears or raisins.  In dry periods, it is a crusty blackish growth on exposed caliche soils and is easily missed by the casual observer. During rains, however, Tree-Ear absorbs water, and expands to look like a human ear.

Tall grasses and forbs typically cover most prairie soils, but cryptogams can be found on exposed outcrops as well as on old gravel pits along Spring Creek. Cryptogamic soils are generally more western and in more arid climates, although they do occur in Florida. Identification is difficult, if not impossible, without a microscope and chemical tests.

Succession on shallow soils and exposed rocks:

These soils were most likely maintained by periodic wildfires. The shallow soil depth limits growth to cryptogams and a few species of forbs and grasses.  Once organic matter is built up, the cryptogamic stage typically succeeds to moss-covered soil with Woolly Ironweed, Barbara’s Buttons, Queen’s Delight, Thelesperma, Yucca, Ratany, Winecup, Redroot or New Jersey Tea, Whitlow-Wort, Missouri Primrose, and other prairie species(see lower right photo). According to Shinners & Mahler’s, “species seen in this type of setting in the northern Blackland Prairie (Grayson County) include Baptisia australis (wild blue-indigo), Callirhoe pedata (finger poppy-mallow), Eriogonum longifolium (long-leaf wild buckwheat), Grindelia lanceolata (gulf gumweed), Ipomopsis rubra (standing-cypress), Linum pratense (meadow flax), Marshallia caespitosa (Barbara’s-buttons), Oenothera macrocarpa (Missouri primrose), Paronychia jamesii (James’ nailwort), and Thelesperma filifolium (greenthread). At some seasons, these outcrops have the aspect of barren eroded rock; in the spring, however, they are covered with spectacular displays of color.”

Shinners & Mahler’s Illustrated Flora of North Central Texas, 1999, George Diggs, Jr., Barney L. Lipscomb, and Robert J. O’Kennon, Austin College & Botanical Research Institute of Texas (BRIT).

Effects of fire on lichens as well as other community species is described in the Forest ServiceFire Effects Information database. The FEIS database contains synoptic descriptions, taken from current English-language literature of almost 900 plant species, about 100 animal species, and 16 Kuchler plant communities found on the North American continent. The emphasis of each synopsis is fire and how it affects each species

More infomation on soil crusts can be found at the Biological Soil Crust page by the Bureau of Land Managment, U.S. Geological Survey, and National Park Service.

Effects of cattle grazing on cryptogamic soils can be found at:

Biological Soil Crusts

Oregon cryptobiotic soils

The Rhizosphere

In many native plant communities such as Spring Creek Preserve, a significant portion of the total biomass is underground…for example, up to 70% of the biomass of a tall-grass prairie is below ground.  The area below ground where a plant’s roots interface with the soil is called the rhizosphere.  The rhizosphere is an area where symbiotic associations between bacteria, fungi, grass rhizomes, forb roots, and other soil biota take place.  Mycorrhizal fungi and nitrogen-fixing bacteria form mutually beneficial relationships with specific plant hosts. The microbial community and activity around a plant’s roots creates what some soil scientist refer to as living soil.  The deeper a plant’s roots go the deeper the living soil.  With extensive deep root systems, native plant species help stabilize the soil column and create an environment favorable to building fertile soils rich in organic matter with a diverse soil biota.

Mycorrhizal Fungi (Soil Fungi)

To one degree or another, most plants in their natural habitats function under the influence of a special groups of soil fungi known as arbuscular mycorrhizal fungi (“AM fungi” or AMF).  Mycorrhizal fungi associate with and connect to the roots of plants.  The plant provides the fungi’s sole source of carbon, in the form of simple sugars exuded by the roots.  The fungal hyphae become an extension of the plant’s roots, increasing the root’s absorptive area by 10 to 10,000 times.  A plant’s relationship with mycorrhizal fungi brings additional benefits.  The fungi help to break down nutrients locked away in the soil, making them available to the plant. Mycorrhizal fungi also help plants to be more drought and disease resistant, and improve soil structure, making them more porous.

It is estimated that 90% of all plant species from some type of symbiotic realtionship with soil fungi.  There are many species of mycorrhizal fungi. Some plants form associations with only one specific species, while others can form associations with a variety of species.  Habitats of orchids, for example, by determined by the habitat of their associated fungus. Orchids require the relationship with a fungus for their existence.  The relationship is essential for the germination in the wild and is essential for a few orchid species throughout life.  Many species within the family Scrophulariaceae and particularly with the genus Castilleja, or Indian Paintbrush,  is considered to be a facultative root parasite or hemi-parasite…the only way for a paintbursh to survive is to stick it’s tubes, called “haustoria” into the roots of a host plant.  Studies have also shown that species in the family Poaceae benefit greatly from mycorrhizal colonization in termsof growth and nutrient acquisition. Phosphorus nutrition of  grasses in tallgrass prairies is immediately tied to fungi.

The mycorrhizae community of soils is sensitive to disturbance.   In many man-made landscapes we have reduced or eliminated healthy diverse populations of mycorrhizal fungi. With the heavy use of fertilizers and pesticides, the compaction and paving of soils on construction sites, off-road use of vehicles, and loss of topsoil through tillage and erosion the population of these beneficial fungi have greatly declined or been eliminated in many areas, particularly agricultural and urban landscapes.

Adapted from JFNew Native Plant Nursery 2002 Catalogue
Soil Biota links

National Soil Survey Center – Soils & Science Web Sites


A Gram of Soil

Tardigrades or “Water Bears”

Tardigrade Links

False Earth Star

Although not cryptogams, false earth stars are sometimes found in nearby areas of shallow soil during fall.  Other  interesting inhabitants include a camouflaged grasshopper which blends in with the Austin chalk…it is probably the Three Banded Grasshopper, Hadrotettix trifasciatus.

Special thanks to Barbara Keeler, US Environmental Protection Agency,  for her discovery of cryptogamic soils at Spring Creek.