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In nature there are no absolutes, all are biases. It is the equivalent of your diet and life style. If you drink and smoke heavily, overeat at every meal, and use drugs, it is more likely you will have health problems. The more things are wrong with your landscape design the more likely it will be a weedy mess.

Plant communities

If you try to define the community of California, the dominant variable is the relationship between plants. Animals, insects, even people seem to follow where the plants have been.

Plant communities should be viewed as living systems. Native landscaping is easy if you put the plants back into the community where they live. Coastal sage scrub plants get planted into coastal sage scrub gardens and Gaia lives.


90% of the native plants in California's Wildlands are mycorrhizal and thus interconnected. Isotopes have been used to trace the invisible links. That is, isotopes placed in one plant turn up in another. Native plants share moisture and nutrition. This interconnection is accomplished by many types of fungi, as a group they are called mycorrhiza, meaning Fungus root. Mycorrhiza provide a much larger root system, 100 times longer, and up to 2000 times more surface area. Mycorrhiza develop a soil community that supports friendly bacteria, nematodes, springtails, earthworms, etc., and inhibits herbivores and pathogens.

Yucca in the chaparral plant community. - grid24_12
The chaparral Plant community has all sorts of unusual plants.

Think of the underground mycorrhizal system that exists in most native systems as a large interconnected savings account or the immune system for all the native plant roots.

Mycorrhizae and Plant communities

This shows up in stable plant communities by total weed suppression. If the plant is not part of the community it is not allowed to survive. Regeneration of the community only occurs after a fire or some other major disturbance.

New plants are not allowed to regenerate within the community unless there is a 'hole' in the pattern. (This showed up in a test in Mojave, where the plants had been scraped off there was a higher survival rate of planted plants than where the plants were planted in between the existing stand. The whole is more important than the individual.)

It is useful to view a plant community or your garden as a living being with an immune system. (Gaia) Think of it as one large organism instead of lots of little ones.

Mycorrhizal roots

For years we couldn't figure out why all the books, our biology classes, articles, etc. talked of pearly white roots. We have only a few species in the nursery with pearly white roots. Although you cannot tell if a plant has mycorrhiza on it by visual means,  we've noticed a general trend for only the non-mycorrhizal plants to be pearly white. This is apparent when non-mycorrhizal weeds come up in a pot with a mycorrhizal plant.

Soils with little organic matter that are low in Phosphorus favor VAM plants. Deserts, grasslands, tropical forests may be the same species of VAM for miles, all interconnected.

Ectomycorrhizae occur on all Pines, Oaks, Firs, etc. They are visible to the naked eye and can be orange, yellow, brown, or black. Soils that are low in phosphorus and nitrogen favor Ectomycorrhizae. Ectomycorrhizae occur in temperate forests, some chaparral and tropical forest areas. Ectomycorrhizae are the stress tolerants in all the Mediterranean climates except S.Africa. The largest of this fungus to date was 5000 acres. This fungus covers that many acres, but it does not exist alone, an oak or pine tree may host 150 species of mycorrhizal fungi, all with a different niche on the tree. Some are favored in winter, others in summer, some favored by clay soil, others sandy. A forest may have 2000 types of fungi all co-habitating with little or no competition. They recognize each other and each live in their own niche. In a normal yard there may only be 20 or so. Ectomycorrhizae live above VAM, just below the litter layer.

Ericoid overlap greatly with the Ectomycorrhizae. Sometimes one fungus can be one type on one root and another on an adjacent root. This occurs quite often on manzanitas. Soils that are high in organic matter, but low in both Phosphorus and nitrogen favor Ericoid plants. Ericoids are not dominate anywhere. The largest area I've seen is in the sandy plain around Ft. Bragg.

A great deal of the garden annuals and perennials are non-mycorrhizal. Most weeds are non-mycorrhizal or facultatively mycorrhizal (They are associated with a fungus only where it helps them). Non-mycorrhizal plants occur where there is adequate nutrition and moisture.

Climate, community (plant & soil), and soil type are equally important.

You cannot separate the three, they all influence each other.

Climate: The most important aspect of climate is the amount of rainfall and how it comes down. For example, Monterey's summer fog drip increases that area's rainfall by 40% or so. The 25 inches of rainfall they receive is actually closer to 35 inches. The summer fog decreases the summer desiccation and keeps the mulch moist. (This is one of the reasons so many manzanitas live in that area.) Many of the desert areas get small amounts of rain all year. This plays havoc when they are planted in an area of seasonal rainfall, and the plants often die of drought unless they are part of that community.

Soil: The climate often makes the soil. Rainfall areas of 10" or greater rainfall usually have neutral to acid soils, areas of less than 10" usually are alkaline. If that rain never comes in large numbers the alkalinity is greater. Plants can modify pH one unit; in extreme cases, nearly 2 units. If a plant comes from a soil pH greater than 2 units from yours you cannot have it. It will survive poorly at best. The plants can modify, but not alter the basic nutrition available in a soil. If the plant grows in serpentine clay, it will not be able to grow in sandy loam, unless the plant was part of that plant community.

Plant community: the plants and microganisms that grow on a site depend on these factors. Certain manzanitas for example like clay others like sand. Some plants like high acidity others more basic soil. On the other hand in many areas the plants play a huge role in soil type and rainfall. For example along the coast of northern California huge redwoods help catch fog and cause it to condense adding at least doubling their rainfall. These trees could not grow in these locations without that added rainfall. The shadscale scrub has a similar role in the central valley in collecting tulle fog. Also many plants will drop their leaves lowering the pH of their soil.

Looking up into the redwood trees. The tallest trees in the world are California native plants. - grid24_12
Tall trees in the forest are like the skyscrapers in the city. These trees create their own climate.

Circumventors (C plants)

(Grime used the word competitors, people do not understand the way the name is applied so we've changed it to circumventors.) Circumventors shut down if they feel drought or cold, Circumventors build their cycle around the stresses of their associated communities. Many of California's chaparral plants go summer dormant to avoid the drought-stress. Many of our wildflowers only germinate on wet years. Our bunch grasses are circumventors because they live long lives but will not show themselves on dry years. In our ecosystems circumventors are along the seasonal creeks, and between the perennial creeks and dryland. They'll often act as water and nutritional shunts between sites. Many circumventors can have both VAM and Ectomycorrhiza on their roots. (Most circumventors are VAM though.)

Characteristics include:

Many flowers during their flowering period and usually are not weedy.

Community oriented (provides support for the fungal grid and animals)

Can be very drought tolerant by avoiding drought

Disappears or goes deciduous under stress, only to reappear when the stress is removed.

Can be long lived. Common life spans are 5-500 years.

Amphibians fit this, as does the poker player that folds a lot.

A Pale Swallowtail butterfly on  the Redbud, Cercis occidentalis, the inset shows Golden Currant, Ribes aureum gracilentum flowered exactly right.  - grid24_12
Western Redbud

Examples include:

Fruit trees


Monkey flowers (Diplacus forms are summer deciduous as they dry out, Mimulus are mostly ruderal)

Many oaks

Most native riparian species (except the ruderal types that are along the disturbed margins)



Most native sages

Penstemon spectabilis, Showy Penstemon can be a very hot lavender addition to a California garden. - grid24_12
Showy Penstemon

Ruderals are the weeds.

They live by competition. They're the first to flower and the first to seed. Ruderals are favored if there is fertility, moisture, disturbance and a messed up plant community. Ruderals only care about themselves (their species). They are non-mycorrhizal or only mycorrhizal if it suits their needs.

Characteristics include:

high nutritional needs*** high water use

Inefficiency at all levels, all is sacrificed for reproduction. Lots of flowers, lots of seedlings.

'Weedy' growth designed to outgrow its neighbors, reproduction can be completely overwhelming.

Insect damage, many of our most troublesome pests live on weeds. Weeds are the host plants for almost all the problem insects.

A short life (2 weeks to 5 years) with many seedlings.

Hard to kill or control as the seeds can be viable at 10% maturity and there are so many produced. Kill the first crop of weeds, a second crop comes up, kill that crop and a third crop shows up . . .

Weeds are individualistic to their species (as starlings). Weeds try to create anarchy.

Very competitive (any fungi or bacteria associated with them are also ruderals), even with themselves.

Ruderals can lead to the collapse of a stable native site. Ruderals favor soil bacteria. Ruderals often kill stress tolerants by exclusion of the fungal partners. Ruderals need bare ground (no mulch layer)and favor bare ground.(They create bare ground by favoring frequent flashy fires, soil slippage, bacteria, rodents (gophers, mice, voles), and other factors that expose soil.) Once the weeds come into a site or garden, things get difficult, as hand weeding favors ruderals.

Getting rid of ruderals

Infection is hard to get rid of without antibiotics (you can't hand remove each infection site), as ruderals are hard to remove without herbicides. In a native ecosystem herbicides=antibiotics. They are less invasive and more weed specific.

If you have a staph infection on your arm, scraping it off with a knife will not help your body. Hoeing weeds is similar. Not all herbicides are equal. The auxins like 2,4-D or 2,4,5-T move through the system and can kill the native species. Many of the long term sterilants are a big no no. they kill all the good soil organism and make the site ripe for weeds. If you do not know what is a weed, or what kills what, learn, or hire someone that does.

Insecticides, are a different matter. If there is a bug invasion on a native plant or other xeriscape type plant (circumventor or stress tolerant) you did probably something wrong! Their plants immune system should keep the bugs off. Ruderals are insect food. Since ruderals only care about reproduction they spend almost no energy on protection. Natives are the opposite of conventional plants, you should not have to spray.

Fungicides are death to drought tolerants because you will kill the endophytes, above ground and below ground.

Confusing symptoms

Plants that live in sandy soils often cannot match the mycorrhiza and associated microflora that live in clay and thus look chlorotic. Tilling in soil amendments only helps ruderals. Plant material that is native to an area with a soil pH no more than 2 units different than yours. A soil fungus that grows in soil pH of 5 will not generally survive a soil pH of 7.5. Remember pH is logarithmic. pH 5 is 100 times more acid than pH 7.

Who likes what?

Highly fertile soils that have been disturbed (tilled, disked, etc.) favor ruderals. Growing broccoli?

Low fertility, undisturbed, drier sites favor natives. Weeds have trouble, natives flourish.
Treat soil as a living being. You would not like fertilizer tilled into your skin!

Amendments, polymers, fertilizer, and water for ruderals; water a little extra for circumventors, a little extra water in spring only for stress tolerants(or none at all)

Stress tolerants need 'fluffy' soil, compacted soils favor ruderals. Stress tolerants and to a lesser degree circumventors create a highly aerated soil. Native fungi and friendly bacteria live best in “normal” air oxygen levels and common soil. Do not be 'dumb as dirt' and amend or fertilize your natives.

Fertilizer favors unfriendly bacteria and thus ruderals. Fertilizer can kill a stress tolerant in hours because the mycorrhizal sites are replaced by pathogens.
Creosote scrubland in summer on a dry year. Parts of California get almost no rainfall, but still come alive once a year for a few months.. - grid24_12
Creosote woodland looks dead on a dry summer day, but there can be more diversity here than a heavily timbered forest.

Bad ecology in practice

Example 2: the USDA is breeding single species mycorrhiza to inoculate clones of the most aggressive trees they can find. The results are very impressive in the lab and nursery but the mortality in the field is very high and the resulting forests are very unstable. Instability means high mortality, weeds, insect damage, herbivore damage, etc.. Once you see or develop a stable site you'll never accept less. University Oregon at Corvallis tests has shown that for a forest to be stable you have to have other species besides pines and firs.

Example 3: For years we had our customers watering once a month after the first year, gradually reducing the watering to once per summer. As we got a closer match to the site's needs we got reports back that 30% of the plants died a week after they watered. The plants looked fine before the watering, but a week later were dead. We've heard the same reports over and over after a fertilization, a spraying or 3 years on drip irrigation. The reasons for these losses are all the same, summer watering, fertilizer, and drip favors bacteria. The plant will 'drop' its mycorrhizal association unless it is under slight to moderate stress. When it drops its fungal partner all those sites on the root are immediately replaced by pathogens. So a Fremontia or Ceanothus will be glorious one day and dead the next, with one heavy summer watering.

Example 4: Where the plant is grown matters only if the climate is much 'softer' than your site. Plants grown in very mild climates cannot adapt to harsh climates.

Stahl and his group did a study with Glomus mosseae a common VAM fungi, they collected spores from Oceano carrot fields, Sage Brush fields in Utah and Wyoming. They grew grasses in a greenhouse in Wyoming with these three fungi. In the greenhouse the carrot fungi grew 8 times better. When these same plants where planted out however, the situation reversed, the carrot fungi were 5% mycorrhizal and the sagebrush fungi were 70% mycorrhizal.

Remember you can give extra water to stress tolerants or circumventors only during their normal moisture cycle, i.e., Mediterranean plants in winter-spring, desert plants a little extra in summer, and forest plants in spring-early summer. All the plants like to have their foliage washed off regularily.

California Native plant Community plantings:see also the plant community pages

Look to mother nature and plant using plants of the site's community and soil type. The closer to matching the garden's plant community, the better the planting behaves. A perfect match will not need to be watered, weeded or managed after three years. Matching the plant community also matches the climate. Forget the Sunset zones, match the plant community as the climate has already dictated the plant ranges. The second best choice is to choose plants from the associated groups. (Habitats, or plant type). The third best is choice are plants from the same type soil and plant community from around the world.

Plant the R types near the water source, the C types next and S types as far as possible from the water source.


These next two are warm communities that rarely see hard frost. Dry summers.

Plant community

Dominant Mycorrhizal fungi (most to least)

Rainfall, and other characteristics

Coastal Prairie


20-35in, Mild

Valley Grassland


7-35in, Hot, This community can see frost at anytime, is a desert 9 months of winter, and a near swamp in summer.

Alpine Fell-Fields


30-40 in, Cold

Mountain Meadow

NON in water,VAM on edges, ectomycorrhiza in bogs

Always moist, spring wet

non-native equivalents: pampas, American prairie, northern marshes

A Fritillary Butterfly on a Helenium bigelovii in a Sierra Meadow. - grid24_12

COLD DESERTS (also called steppe communities)

Plant community

Dominant Mycorrhizal fungi (most to least)

Rainfall, and other characteristics

Northern Juniper Woodland


7-12 in, the ground freezes to 4" or more

Great Basin Sage


7-10 in, the ground freezes to 4" or more

Sagebrush Scrub


5-15 in, the ground can freeze most years to 1-4"

Non-native equivalents: steppe areas of Russia, Mongolia, Tibet, etc.

Dominant Type Mixed plant communities

Both forms of mycorrhiza are present and the forms that exist here are mutually supportive.

Very Irregular rainfall or large seasonal change. In many of these communities fog drip accounts for much of the precipitation. These are the transition communities that live between Dominant California Forests and Dominant Desert


In these communities ectomycorrhiza and VAM are dominant in mosaic patterns between the trees or manzanitas. The energy capture of the communities are based on forbs and wildflowers that are VAM, plus the majority of shrub-covered areas are VAM. ectomycorrhiza covers the surface layers between ectomycorrhiza plants, VAM covers the rest of the area and below the ectomycorrhiza 6-12" Boulders near each plant and mulch between plants is best, but just mulch is OK.

Has a strong Plant community

Dominant Mycorrhizal fungi is patchy between VAM and Ectomycorrhiza

Rainfall, and other characteristics are summer drought and wet winter


Coastal Sage Scrub

VAM ,ectomycorrhiza,ERICOID

12-25in, (Little summer heat)

Northern Coastal Scrub


35-70in, (Little summer heat)

Redwood Forest


40-60in, (High humidity,low heat)

Mixed-evergreen Forest


20-60 in

Northern Oak Woodland


30-40 in

Non-native equivalents: So. France, Italy, Spain, Portugal, S.E. Australia, N.Zealand, S. Africa

Coastal sage Scrub south of San Luis Obispo with Sticky Monkey flower, California Sage Brush, Coast Live Oak, and Poison Oak. - grid24_12


Pinyon-Juniper Woodland


7-12 in

Bristle-cone Pine



California Pinyon-Juniper Woodland with a Pinus monophylla - grid24_12

Non-native equivalents: Western Australia, N. Venezuela, Israel, Algeria



always near a water source

The riparian trees generally move water up into the plants on the banks. To do this many are both ectomycorrhiza and VAM.(Salix,Populus, Alnus,wet land Oaks, Betula etc.) We view lawns as a riparian area.

How to put together natives and non-natives. It is useful to think of these as ecological equals or native plant substitutions for common California garden plants.

Sunrose=low manzanitas groundcover=Arctostaphylos edmundsii

Natives for transitional areas between watered and dry areas (Between a lawn and a dry slope, or between a lawn and oak tree.)

If substituting, don't forget:

The Non-natives do not provide much support for the native insects, animals and soil fauna. It is important to include and least some community specific plants in all plantings. A 'wildlife garden', bird garden, or butterfly garden is nothing more than a community(and adjacent) specific garden.

Other stuff

Weed control and a California Native Plant garden

How to plant California native wildflowers.

A Short lesson in planting, mulching and watering California native plants

Native plants, mulch and amendments in garden soils. Oak, chaparral, pine mulch all fine, redwood is better. Use straw to make a weedy mess. Green waste is a waste.

Drought tolerant California Native Plants need little or no water. Water, first watering is 50% of the water needed, second 25%, third 12%,etc , Drip irrigation, is bad! But water well.

Other class notes:

Birds and Butterflies
Common Diseases, Pests of native plants
Frankia and California native plants
Garden Myths about California Native Plants
Incredible Edibles
Landscaping with California Native Plants
Native Oaks and Mycorrhiza
Native Herbs
Planting seed or plants after a wildfire

Other places you might find us roaming about:

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Edited on Sep 23, 2012. Authors:
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