Pretty? NO!

The Scotch broom pictured here is beautiful while blooming. But this exotic invasive is like standing gasoline during the summer & fall. See the list below of other invasive plants.

When Masanobu Fukuoka, author & guru of The One-Straw Revolution, visited the Northwest he remarked that we should spreed this plant around because it was such a good nitrogen fixer. Shows what carnage can be considered when you're out of your ecosystem.

California alone is home to 4,200 native plant species, and is recognized internationally as a "biodiversity hotspot." Approximately 1,800 non-native plants also grow in the wild in California. Here’s a short list of just some of the invasive plants in California alone. Data is from the
USDA. NAL. National Invasive Species Information Center.

http://www.invasivespeciesinfo.gov/unitedstates/ca.shtml

It’s strange that this list does not include three major invasive plants: ice plant [Mesembryanthemum ssp.], pampas grass, [Cortaderia selloana], and Periwinkle [Vinca ssp.].

NOTE: "3:1 rule: For every year you delay controlling an invasive plant infestation, it will take three years to regain control."

Common Name ( Botanical Name)
Air Potato (Dioscorea bulbifera)
Autumn Olive (Elaeagnus umbellata)

Beach Vitex (Vitex rotundifolia)

Brazilian Peppertree (Schinus terebinthifolius)
Canada Thistle (Cirsium arvense)

Chinese Tallow (Triadica sebifera)
Cogongrass (Imperata cylindrica)

Common Teasel (Dipsacus fullonum)

Dalmatian Toadflax (Linaria dalmatica)

Diffuse Knapweed (Centaurea diffusa)

Downy Brome (Bromus tectorum)

Fig Buttercup (Ranunculus ficaria)
Garlic Mustard (Alliaria petiolata)

Giant Hogweed (Heracleum mantegazzianum)

Hairy Whitetop (Lepidium appelianum)

Houndstongue (Cynoglossum officinale)

Japanese Stilt Grass (Microstegium vimineum)
Japanese World Climbing Fern (Lygodium japonicum) 

Japanese Honeysuckle (Lonicera japonica)

Japanese Knotweed (Fallopia japonica)

Japanese Spiraea (Spiraea japonica)
Johnsongrass (Sorghum halepense)

Kudzu (Pueraria montana var. lobata)

Leafy Spurge (Euphorbia esula)

Medusahead (Taeniatherum caput-medusae)

Mile-A-Minute Weed (Persicaria perfoliata)

Multiflora Rose (Rosa multiflora)

Musk Thistle (Carduus nutans)

Old World Climbing Fern (Lygodium microphyllum) 

Oriental Bittersweet (Celastrus orbiculatus)

Princess Tree (Paulownia tomentosa)
Purple Star Thistle (Centaurea calcitrapa)

Quackgrass (Elymus repens)

Russian Knapweed (Rhaponticum repens)

Russian Olive (Elaeagnus angustifolia)

Saltcedar (Tamarix spp.)

St. Johnswort (Hypericum perforatum)

Scotch Broom (Cytisus scoparius)

Scotch Thistle (Onopordum acanthium)

Spotted Knapweed (Centaurea stoebe)

Tree-of-Heaven (Ailanthus altissima)

Tropical Soda Apple (Solanum viarum)

Whitetop (Lepidium draba)

Witchweed (Striga asiatica) 

Yellow Star Thistle (Centaurea solstitialis)

Yellow Toadflax (Linaria vulgaris)

Green Manures, free nitrogen

It's almost too late plant fava beans, a legume, in the fall. The soil needs to be somewhat warm. This may work in gardens in sunny gardens in the west and south-west gardens. Alfalfa works the best with corn, but this is just for planning next years spring garden. Leave room in your plans to grow some green manures. I'm using another fava bean flower as it's the only one I have without scanning a slide, which I'm to tired to do this morning. :=)

Legumes have gotten a lot of attention because of their ability to fix, via symbiotic bacteria that colonize the plant's roots, atmospheric nitrogen gas into available, "free" fertilizer. Because gardeners are preoccupied with the amounts of nitrogen in their soil, they are often fixated on legumes as a green manure. While legumes are important in a green manure mix, they are not a panacea. And a myth, or lack of understanding, about how this nitrogen fixation really works has confused gardeners and reduced their chances to maximize the nitrogen cycle.

The common perception that growing beans and corn together will help fertilize the growing corn plants is incorrect. Nitrogen-fixing plants, in temperate climates, didn't evolve to directly share the accumulated nitrogen with other plants. The ability to fix free nitrogen "out-of-thin-air", in the bacterial nodules on the roots, is a competitive, evolutionary development. This allows leguminous plants to colonize nutrient-poor soils. Legumes are some of the first plants to inhabit disturbed soils such as landslides, cliffs, beaches, sand dunes, and fire-scorched soil. When you think about it, the compacted clay subsoil that's left after most houses are built is really a disturbed soil. The legumes use all the nitrogen they accumulate to grow and make high-nitrogen seed. While the plant is growing, the nitrogen from the nodules on its roots is temporarily "banked", or stored, in the stems and leaves of the plant. This provides plenty of nitrogen for rapid assimilation into the blossom once seed begins to form. Consequently, the green bean plant growing up a corn stalk isn't about to share its nitrogen with the corn, during the current growing season. The mature beans contain 70 to 90 percent of the entire plant's total nitrogen. After the bean drop is harvested, the roots and their nodules have as little as three to six percent of the plant's total nitrogen--not much of a legacy, or fertilizer portfolio for the "heirs". So, to harvest a bean crop and till under the dry tops of the plant means you'd be getting only a very tiny amount of nitrogen back into the soil because the seed has most of the nitrogen, little nitrogen is left in the stems, roots, and leaves, and the tops are too carbonaceous for easy decomposition. (See illustration on pg. 265 of my "Edible Landscape" book.)

During the growth of a legume, very limited amounts of root nodule nitrogen can become available when the stress of grazing, mowing, drought, or death causes some of the nodules to wither, die, and rot in the soil. This is why the old way of grazing animals on pastures of mixed grasses and legumes works so well. When the cow grazes the pasture, some of the nodules on the legume's roots "shed"--they don't really jump anywhere, they just decompose--the grasses are able to quickly absorb the freed-up nitrogen for their growth. This makes for more pasturage, which entices the cows to eat some more. Meanwhile, the nitrogen-rich legume plants and bulky grasses makes for a goodly amount of nitrogen to be recycled via the bovine posterior--with deposits called meadow muffins, pasture patties, or cow chips.

"Free" Nitrogen with Good Timing

The optimal time to till under a green manure crop for maximum nitrogen (for a subsequent crop) is just before the blooms appear. The conscientious green manurer, must "sacrifice" beautiful blossoms for the optimal amount of nitrogen. I was visiting Ros Creasy one year when almost one third of her front yard had Crimson clover in full, glorious bloom. I timidly mentioned that the best effect for nitrogen occurs prior to bloom, or up to 20 percent of bloom. "Yes," she replied, "I won't get as much nitrogen, but look how absolutely gorgeous the bloom is! I don't mind giving up a bit of the nitrogen for the floral display. Besides, Crimson clover has a decent amount of nitrogen to spare and my soil isn't in horrible shape." Yep.

Let me know what you think.

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Thinking About Tropical Diversity (in the redwood forest!)

On my daily walk, the forest of redwoods (Sequoia sempervirens) the S. gigantea is pictured here), oaks, Douglas firs, and many understory plants seems rather diverse. I wondered if this diversity had any implications to gardens. Maybe yes, maybe no. But today, for some reason I'm thinking about the tropics as well as the temperate climates.

In my opinion, using tropical diversity as a model in the USA is childlike. While the tropics often have lots of vertically-integrated plants, the temperate American landscape, with its hardwood forests, meadows, and prairies, is less vertically complex.


The nutrient mass is primarily above the ground in the tropics, the soil is rather “thin”. By comparison, the deeper soil is the reservoir of nutrients in a temperate ecosystem. Some plants in the tropics actually fix nitrogen on their leaves – “Experiments in a Costa Rican rainforest revealed that fixed nitrogen [by blue-green algae] is directly transferred into the leaf “ (Many tropical plants and trees do fix nitrogen in the soil, but it is “recycled” much more quickly.) From MONGABAY.COM: “The colonial settlers did not realize that they were dealing with an entirely different ecosystem from their temperate forests where most of the nutrients exist in the soil. In the rainforest, most of the carbon and essential nutrients are locked up in the living vegetation, dead wood, and decaying leaves. As organic material decays, it is recycled so quickly that few nutrients ever reach the soil, leaving it nearly sterile”. While in the temperate climates, nitrogen-fixing bacteria grow only the roots beneath the soil’s surface—primarily Rhizobium spp. bacteria found on the roots of the bean family (Fabaceae or Leguminosae) gather the nutrients, especailly nitrogen.

The difference is considerable when applied to the practical. Gardeners in temperate climate work to enhance the fixation and storage of nitrogen the soil mass. While tropical gardeners can rely on foliar feeding of nitrogen and the rapid recycling of nitrogen in a thin soil. (Sugarcane production requires no additional nitrogen due to the independent fixation of this element.)


Please post a comment - I want to know what you think.

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Note: I somehow lost the usual section "Post a comment". To leave a comment, simply click on the area/button that says "___ Comments" below. Or,clicking on the title of a Post under "Blog Archive" also gets you to a view that gives the option of leaving a comment. Robert