Silver Wattle

Silver wattle is a magnificent weed.

Almost everyone on the West Coast of California has encountered silver wattle, Acacia dealbata. Some of us know how resilient it is to most methods of eradication. The more fortunate enjoy its magnificently bloom from a distance. It is almost never planted intentionally. It is an aggressively naturalized exotic species. Most grows wild near roadside ditches. Some invades home gardens.

The profuse and bright yellow bloom of silver wattle is spectacular while most deciduous trees remain bare late in winter. Big and billowy trusses of smaller round floral structures obscure most of their slightly grayish foliage. The many individual staminate flowers within this impressive bloom are actually minute. Their hearty floral fragrance is appealing to some, but objectionable to others.

Silver wattle lives fast and dies young. Some trees are so vigorous while young that they are unable to support their own weight. Without appropriate pruning, they simply fall over. Even stable and structurally sound trees deteriorate after about thirty years. Few survive for fifty. They seed prolifically though! Mature trees can get forty feet tall. The finely textured foliage is bipinnately compound.

Tree Of Heaven

Tree of Heaven or tree of Hell?

‘A Tree Grows In Brooklyn’ documents the resiliency and invasiveness of the common but typically undesirable tree of Heaven, Ailanthus altissima. Once a single female tree get established, the extremely prolific seeds get everywhere, including cracks in concrete. The resulting seedlings conquer wherever they are not dug out. If cut down, they just resprout from the roots.

Male trees smell horrible while blooming for about a month in spring or summer. They are pollinated by flies, so naturally smell like what flies like. The tiny yellowish or tan flowers hang on panicles that can be a foot and a half long. Female blooms are not as big, prolific or objectionably fragrant. However, stems, leaves and all other parts of both genders smell rotten when handled.

Tree of Heaven, which has earned the alternative names of ‘tree of Hell’, ‘stink tree’, ‘ghetto elm’ and ‘ghetto palm’, is no longer a tree that gets planted by choice. It is typically a tree that plants itself, and on rare occasion, happens to grow into a good situation. They should not be allowed to overwhelm more desirable trees, or get too close to concrete or other damageable features.

Young trees grow very fast to about forty feet tall. Older and slower trees do not get much taller, although sheltered trees can get twice as tall, with elegant gray bark. They do not live much more than fifty years. The big pinnately compound leaves are surprisingly pretty. On vigorous shoots, individual leaves can get as long as two and a half feet, with leaflets as long as six inches.

Santa Barbara Daisy

Some of us know Santa Barbara daisy by the less appealing name of ‘fleabane’.

Santa Barbara was not exactly its first choice. Santa Barbara daisy, Erigeron karvinskianus, is not even native to California. It is actually from Central America. It just happens to do very well here, and can naturalize if conditions are right. It can be rather grungy through summer in the wild, but with a bit of watering, it can bloom nicely all year.

The thin stems can spread a few feet without getting more than a foot deep. If even shallower growth is preferred, older plants can be cut down or pulled up as they get replaced by their own offspring. The narrow leaves are quite tiny. The white or slightly pinkish flowers are not much bigger, less than half an inch wide, with prominent yellow centers.

Santa Barbara daisy is also known as Mexican fleabane, both because it is actually native to Mexico, and also because it is supposedly useful for repelling fleas. The problem with using it to repel fleas is that only its smoke is effective. There are probably other herbal alternatives that work just as well without being a fire hazard.


Bloom is sporadic, but the delightful purplish blue color is worth it.

If the Latin name of dwarf periwinkle is Vinca minor, it is logical that large periwinkle should be Vinca major. Large periwinkle is more commonly known simply as periwinkle or common periwinkle, although it is not as common as dwarf periwinkle is, at least in landscapes. In some regions, it has naturalized as an invasive weed.

Some might accurately say that periwinkle is shabbier than the relatively neat and dense dwarf periwinkle. Others might say that it is just rustic or informal. The wiry stems stand less than a foot tall before they bend over from their own weight. Fallen stems can root where they touch the ground, and grow into new plants over winter.

The evergreen foliage is rich green, and a bit darker than the top of a billiard table. The simple paired leaves are about an inch and a half to two inches long. The slightly purplish blue flowers are about an inch and a half wide, with five petals each. Bloom is sporadic, but almost continuous, except for a lapse through winter.

Butterfly Bush

Garden varieties are less likely to naturalize than the straight species is.

Many plants are so easy to grow that they become invasive weeds. Butterfly bush, Buddleja davidii, has done exactly that in some regions, and is only controlled here by the arid climate. Yet, once established, it does not need much water at all, and can survive on rainfall in some spots. They only want good sun exposure.

Mature plants can get more than 15-feet tall and half as broad, with long arching limbs. Most garden varieties stay smaller, and some do not get much more than six feet tall. The evergreen foliage is sage green, grayish green or chartreuse. The paired leaves are about the size and shape of willow or eucalyptus leaves.

Conical trusses of densely packed tiny flowers that bloom in mid-summer can be various shades of blue, purple, red and pink, as well as dusty white. Some new varieties bloom soft orange or yellowish orange. The more compact and colorful modern varieties are not as fragrant as old classics are.

Between A Rock And A Hard Place

Where does this delightful columbine think it is?!

Columbine does not do well here. I do no know why. It does well enough in Colorado to be the Official State Flower there. Yet, the mildest of climates is Colorado are harsher than the climate here. It does not get too terribly warm in summer here. Humidity is minimal, but not as minimal as in much of Colorado. Nor does it exceed that of other regions where columbine does well.

We have certainly tried to grow columbine. It just does not work. Some of it succumbs to powdery mildew. Some succumbs to rust. The last batch just succumbed. Because it was expected, I did not bother to investigate. I got the impression that it was taken out by both powdery mildew and rust. Flowers that bloomed so delightfully when planted went to seed on their way out.

That should have been the end of it. I would not mind if someone tries again to grow columbine for next spring, even if it last for only a short while. I just do not expect to see it ever perform well here. None was planted this year. Even if someone had considered it, there was no need to add any prior to furlough, while cool season annuals for winter continued to bloom so happily.

What I certainly did not consider was the few seed that the last batch of columbine tossed almost a year ago. Apparently, at least one of those seed fell from the ledge where its parent plants lived briefly in now absent planter boxes, and into the edge of a small landscape below. It grew into an exemplary specimen of columbine, which is happily blooming as if it were in Colorado!

It is surrounded by a concrete retaining wall, a perpendicular granite wall and a big granite boulder!



French broom seems to be indestructible.

Shortly after silver wattle finishes blooming up high, any of four species of broom begin blooming down low. Brooms and silver wattle often naturalize together. All bloom with the same delightfully brilliant yellow. The four brooms are French broom – Cytisus monspessulana, Scotch broom – Cytisus scoparius, Portuguese broom – Cytisus striatus and Spanish broom – Spartium junceum.

Sadly, none are desirable species. All are exotic weeds. They are only a topic for gardening because they are so aggressively invasive. Not only do they overwhelm and displace native species, but they also enhance soil nitrogen to promote the growth of other exotic weeds! They are unpalatable to deer, and are not bothered by insects or disease. Furthermore, brooms are combustible!

It is best to enjoy their cheery bloom from a distance, where they grow wild where they really should not. The various species tend to dominate distinct regions, with some degree of mingling. Big specimens can get eight feet tall, but do not live long as they are replaced by herds of seedlings. French broom is the only evergreen species; but any can defoliate in response to hot dry weather.

Wild Strawberry?

Wild strawberries are worth salvaging.

Under a bank of carpet roses that I am none too keen on, this grubby ground cover competes with more aggressive weeds. To me, it looks like common mock strawberry, Potentilla indica. I never gave it much though. It seemed to me that whoever had installed cheap and common carpet roses on that bank would have employed a comparably cheap and common ground cover.

The ground cover was more prolific in open spots that were too narrow for more of the roses, and from there, seemed to have migrated under the roses as a second layer of ground cover. It would not have been installed underneath intentionally. It did not occur to me that it may have grown from seed like so many other weeds there, or migrated in from the surrounding forest.

The white flowers did catch my attention though. I was not aware of a mock strawberry that bloomed with white flowers. I really was not concerned enough about it to investigate. This part of the landscape will be getting renovated soon anyway. The roses will be relocated to where they can not extend their thorny canes into an adjacent walkway. Agapanthus will replace them.

Now that I am seeing more of these odd strawberries, I am wondering if this low ground cover that I formerly had no regard for is actually the native wild strawberry, Fragaria californica. Not only should mock strawberry bloom with yellow flowers, but it should also produce more spherical berries. Now I will need to identify it before I either dispose of it, or merely relocate it.

I prefer to not salvage exotic species that exhibit potential to naturalize from landscaped areas into surrounding forests. If this ground cover is wild strawberry, it migrated from surrounding forests into a particular casually landscaped area.

Unidentified Cyclamen

What species is this naturalized Cyclamen? hederifoliumcoum – feral persicum – or something else?

Could this be Cyclamen hederifolium? Perhaps it is some sort of Cyclamen coum, or possibly feral Cyclamen persicum. I really do not know. Common florists’ cyclamen is the only cyclamen that I have any experience with. I grew it as a perennial when I was in high school, but never saw any feral colonies growing from self sown seed. I have never met the other species before.

Several colonies of this naturalized species of Cyclamen grow wild in the garden of a colleague. No one knows how they got there. I noticed them while procuring specimens of what might be other species that I have been wanting to grow, even though I am not certain of their identities either. I suspect that one could be Sorbus americana, and that another could be Rhus glabra.

I have been wanting to try growing Cyclamen hederifolium or Cyclamen coum since I saw it in pictures of home gardens in other regions. It looks something like common florists’ cyclamen that I enjoyed growing so many years ago, but more natural and relaxed. As much as I like florists’ cyclamen, the brightly colored flowers look a bit too synthetic for naturalistic landscapes.

Even though interesting species of Cyclamen have been available online and from mail order catalogs for at least the past several years, I have been hesitant to try any. I just do not know if they would be happy in forested landscapes where I want to grow them. Not many perennials perform well with so much overwhelming and mildly toxic debris from redwoods and live oaks.

Now I can see that they perform well enough here to naturalize, even under big and messy coast live oaks. In fact, I am now concerned that they have potential to become invasively naturalized in surrounding forests.

Field Of . . . ?

P91228KThis . . . was a ball field. It might eventually be one again. The old backstop at the upper left corner of the picture is almost completely obscured under a thicket of blackberry brambles and a fallen boxelder. It would need to be replaced. So would the decommissioned irrigation system, all the bases, the basepath, the turf . . . and everything else that goes into a functional ball field.

The turf had naturalized and overwhelmed the basepath long before last year. I collected wild mustard, radish and turnip greens from around the perimeter last spring and summer. By the time they were finishing, the blackberries were ready. I got stinging nettle from the bank of Zayante Creek in the background of this picture. Dock is already regenerating off to the far right.

There are naturalized wildflowers here too. I got pictures of perennial pea, purpletop vervain, Saint John’s wort, four o’clock, calla, narcissus, teasel, common thistle and California poppy, all within the perimeter of this ball field. Native trees include Douglas fir, California bay, California buckeye, bigleaf maple, white alder, cottonwood, coast live oak, canyon live oak and redwood.

The ball field looks like the moon now only because a construction company used it as a parking lot for trucks and machinery. We dumped excess soil removed from landscapes on the infield, where it was evenly dispersed by the machinery before it left. A low mound of road debris remains just past the foul line in the background. Firewood gets stocked out of view to the far left.

Restoring this meadow to a ball field would be like starting from scratch. The only salvageable asset is the flat space. Even though turf would be the most substantial feature of a finished ball field, a restoration project will involve more engineering and construction than horticulture.