Showing posts with label non-native plants. Show all posts
Showing posts with label non-native plants. Show all posts

Wednesday, September 2, 2009

Invasive Exotics














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.

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

The photo on the left shows how ice plant is invading the native Buckwheat [Eriogonum spp.] The photograph on the right shows a native lupine [Lupinus spp. and subtle red hills covered almost completely by ice plant. Sadly, ice plant was introduced to help stabilize sand dunes. It has escaped from captivity and has spread with a vengeance.

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

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)

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

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Sunday, March 16, 2008

Oh Deer!


It's early in the morning and the first of the graceful deer walks its favorite path from the woods, past the clay shards garden, and into the garden proper.

Alien plants that once were left alone by the deer now become snacks. Thirty years ago, as a new landscape gardener, I planted red-hot poker plants for their dramatic vertical stems topped by the flush of hot orange and yellow clusters of flowers, flowers that readily attract hummingbirds. I relied on these glorious plants until four years ago when the deer started to eat the flower heads. 

Now they eat the flower heads and the foliage to the ground. Similar casualties have been: the Flanders’s field poppies (They lasted four years, I was convinced the deer ate them to get high on the mind-soothing alkaloids—but alas, no morphine.), after 20 years the foliage of the glorious ‘Sunset’ rockrose with it’s hot-pink crape-paper flowers are reduce to stubble, a curious top-set “walking” onion lasted until just two years ago and is now eaten to the ground each summer as the local forage dries up, Euryops shrubs aren’t eaten, just the hot-yellow flowers negating the reason for planting them, the native sea pinks lasted only three years before the deer found them near my house, the native ginger was eaten back every fall only to be a lush thicket in the winter-the list goes on. I planted two types of ceanothus shrubs (the native “Summer Lilac” or tick brush—Ceanothus ‘Dark Star’ and ‘Julia Phelps’). The deer don’t eat the foliage. They just use the shrub to rub the velvet from their antler and destroy entire limbs. After four or five years they need to be replaced—because I love the rich violet color of the flowers. (Eating is not the only hazard. Once a deer simply laid down for a rest on top of a plant it doesn’t eat, gray santolina, thus breaking the shrub to death.

In the forest, the deer graze some on: the tender new growth of the huckleberry shrubs and new shoots of the western ferns; the lower limbs of the thimbleberry and new shoots of the native honeysuckle. They even browse the new growth of poison oak—which suits me fine.

It hurts my intellect, rattles my heart to forgive the deer as they graze upon native plants and evolve to consume well-established alien foliage and flowers. It’s also difficult to appreciate the grace and beauty of the does and their precious fawns when they give birth to two fawns a year compared to the more common birth of just one fawn many years ago, knowing the population is doubling every year due to the lack of enough predators or rampant disease. 

Luckily the deer have yet found the lavenders I grow tasty (nor the gophers). But an ominous hint of the future might be playing out as I’ve seen the naked stem of French lavenders’ blossoms. Having written a the book on lavender, if I loose these plants to the deer I might just throw in the towel (or shrub).

It’s a very difficult horticultural dance to waltz with the changing habits of the deer and strike a balance between alien and native shrubbery. There’s nothing very spiritual about wanting to strangle to death a svelte deer as it grazes on a beloved plant or favored fruit tree. The fawns are a precious addition to each spring, but a danger as they graze in my garden each summer. Deer are one of the best ways to try and deal with attachment. I often loose the battle.

Eight-foot deer fences start popping up when city folk move to the country to protect prized roses and a myriad of other plants that are just entrĂ©es for foraging deer. This leads to a concentration-camp look with the strand of barb wire at the eight foot level. It need not be that way. 

I learned of a special fence that had a 20-year track record of keeping deer out. It was only 4 feet high. But there were two 4-foot high fences 5 feet apart. Since deer can’t talk, I’m left to guess why this seemingly uncomplicated design is so effective. The most common theory is that the deer can’t see enough room between the two fences to land and then rebound over the inner fence. For whatever reason, this configuration seems to work on both flat and sloped sites. (This double fence may not work in cold-weather areas where winters are snowy and harsh and deer become desperate. For one thing, snow drifts might make it easy for the deer to simply walk up to and over the four foot height. For much of the west, it’s a solution worth experimenting with.) 

I built such a fence 18 years ago for a friend and no deer have crossed it. Once a mighty buck got trapped between the two fences. Luckily, he jumped out the way he came, away from the prized roses, strawberry plants, fruit trees and countless other delectables. If you don’t move to fast you can slowly walk an animal back to where it breached the perimeter to see how it got in.

I rent my home and the layout of the house to the road and the garden would make it very difficult to construct. So I’ve settled upon planting exotics.


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


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