Blue Gum

Juvenile blue gum foliage is very aromatic.

This is the primary eucalyptus that earned a bad reputation for all other eucalyptus. Blue gum, Eucalyptus globulus, arrived in California in the 1850s, and grew on plantations for timber. As its timber proved to be of inferior quality, and demand for wood pulp dwindled, the plantations succumbed to abandonment. Feral trees naturalized into adjacent areas.

Although once a common timber and wood pulp commodity, and effective as windbreaks for agricultural purposes, blue gum was never popular for landscapes. Those that inhabit urban or suburban situations were generally there prior to urban expansion around them. They are far too massive, messy and combustible, and inhibit the growth of other plants.

Mature blue gum trees can be significantly taller than a hundred feet, with elegantly high branched form. Limbs that fall freely from such heights are very dangerous. The aromatic foliage is evergreen. Adult leaves are stereotypically lanceolate and curved. Silvery blue juvenile leaves are blunt, sessile (lacking petioles) and more aromatic than adult foliage. Strips of smooth tan bark shed to reveal paler bark.

Exotic Weeds Are The Worst

English daisy gets prolific in lawns.

Exotic species are not native. It is that simple. There is nothing fancy about it. They came from elsewhere to live here. They are not necessarily rare, unusual or innately desirable. Most plant species within most refined landscapes and home gardens are exotic. Native species that inhabit unrefined areas, although trendy, remain unpopular for landscaping.

Not only are exotic plant species not necessary rare or desirable, many are too common or undesirable. With few exceptions, the most aggressively invasive of weeds are exotic. For a variety of reasons, they proliferate faster than native species. Some are aggressive because they are endemic to competitive ecosystems. Most lack natural pathogens here. 

A weed is merely any undesirable plant. Some might be desirable in some situations but not others. English ivy, for example, which is a practical ground cover within landscapes, is also an aggressively invasive weed within coastal forests. Most weeds are annuals or biennials, but others are perennials, shrubbery, vines, aquatic plants or substantial trees. 

An unfortunate reality about exotic weeds is that they are not here by mistake. Generally, their importation was justifiable at the time. Most were ornamental plants for gardens and landscapes. Some came as fruits, vegetables, herbs, cover crops or forage for livestock. Some came as timber. Species that escaped cultivation and naturalized became weeds.

Such weeds compete for the same resources that desirable plants utilize, and are mostly visually unappealing. Some enhance the combustibility of landscapes and forests. A few weeds produce seed structures that are hazardous to pets and wildlife. Even if problems are not directly obvious, weeds disperse seed to share their innate problems elsewhere.

This is typically the best time of year to pull or grub out weeds, although more weeds will grow later. Annual weeds are mature enough to get a good grip on. Soil should be damp enough from winter rain for roots to pull out relatively easily. Weeding will likely require a bit more effort this year because of the extended dry and warm weather since December. 

Invasive Weeds Waste No Time

Aggressively invasive exotic species become weeds.

With few exceptions, the most aggressively invasive weeds here are exotic. In other words, they are not native. They came from other regions where they were likely compliant participants of their respective ecosystems. At home, where they must compete with other members of their ecosystem, they may not be so aggressively invasive. Ecology is the opposite of a home field advantage.

Exotic species become invasive weeds in foreign ecosystems for a variety of reasons. For some, the climate is more favorable. Some grow and proliferate more freely without diseases, insects and animals that troubled them back home. There are also several that simply compete more aggressively for space and resources than native species are accustomed to. It is a jungle out there.

Most invasive exotic species are annuals. Many are biennials or perennials. Some are vines, shrubs or even trees. Most were imported intentionally, for a variety of reasons, and then naturalized. Forage and cover crops were some of the earliest of exotic species to become invasive. Other invasive species escaped from home gardens. Blue gum eucalyptus was imported for wood pulp.

Regardless of their origins or physiological forms, invasive species are weeds. They compete for the same resources that desirable plants use. They impede on the aesthetic appeal of gardens and landscapes. Some types of weeds become hazardously combustible. Even if not directly problematic, invasive weeds disperse seed that can be problematic nearby. Many disperse stolons.

Most weeds start early and grow fast to get ahead of their competition. They are more active at this time of year than at any other time. They are also vulnerable. While the soil remains damp from winter rain, they are relatively easy to pull intact. They have not yet dispersed seed for their subsequent generation. Later, they are likely to leave behind seed and bits of roots that can regenerate.

It is important to pull or grub out seedlings of unwanted shrubbery and trees, as annual weeds. They are likely to regenerate if merely cut.

Weeding Earlier Rather Than Later

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Rain makes weeds grow like weeds.

Weeding is not much fun. Some of us might enjoy the relaxing monotony of productive weeding. Realistically though, most of us would prefer to do something else in the garden. There is certainly plenty of other chores that need to be done now, after earlier rain, and before the weather gets significantly warmer. However, such weather is why it is important to start weeding earlier than later.

By definition, weeds are weeds, because they are unwanted. They get to be unwanted by dominating space and exploiting resources more aggressively than wanted plants. Some innately grow faster and more aggressively than most other plants. Some are innately prolific with seed. Some employ multiple tactics to gain unfair advantages. Weeding is how we help our gardens compete.

Weeds grow throughout the year. Most slow down through the dry warmth of summer, and many die off then. However, there are always some weeds growing somewhere. When they die off, it is only after they have dispersed seed for their next generation. Some generate a few generation annually. Some are perennial weeds, or even shrubs, vines and trees, which survive for many years.

Weeding is more of a concern now because the majority of weeds grow so much more aggressively after the earliest rain of winter. Warming weather later in winter accelerates their proliferation. This is the time of year that weeds start to crowd desirable plants. If weeding is delayed for too long, weeds eventually bloom and toss seed. Some weeds extend stolons to disperse vegetatively.

The good news is that the same rain that promotes the proliferation of weeds also facilitates weeding. Weeds are easier to pull while the soil is still damp than they will be as the soil dries later in spring and summer. Also, while weeds are still fresh and turgid, they are less likely to leave roots or stolons behind in the soil. They are more difficult to pull intact as they begin to deteriorate later.

Furthermore, weeding should be done before weeds bloom and disperse seed for subsequent generations. Some are sneaky and quick.

Unidentified Cyclamen

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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.

Nature For Sale

P90323KGardening is unnatural. Yes; quite unnatural. So is landscaping. It all involves planting exotic plants from all over the World that would not otherwise be here, including many that are too extensively and unnaturally bred and hybridized to survive for long even in the natural ecosystems from which their ancestors were derived.
Unless they grow on their own, even native plants are not natural. Those that are native to the region may not be native to the specific site. Many that are grown in nurseries are unnaturally selected varieties or cultivars. To complicate matters, much of what seems to be natural out in forests and wild lands are invasive naturalized exotics.
The weather above and most of the soil below are natural, but both are commonly enhanced for our gardens. We water our gardens and landscapes as if the weather is insufficient. Soil amendments and fertilizers compensate for what we perceive to be inadequacies of the natural soil. Insects, deer, raccoons and disease are all natural too, but we put quite a bit of effort into excluding them from our gardens.
Bees and other pollinators are all the rage now, even though many are not native or natural here. We provide them with weird and confusing new cultivars of flowers that likely produce nutritionally deficient pollen, and that distract them from naturally native plants that rely on them for pollination. It all gets so confusing!
These potted annuals and flowering perennials at the supermarket are pretty and might provide the illusion of bringing a little bit of nature closer to the home. Yet, there is nothing natural about them. They are all unnaturally bred and hybridized from unnaturally exotic plants, and were provided with synthetic fertilizers and artificial irrigation, while they were grown in synthetic medium, contained withing synthetic pots.

Weeds Obviously Grow Like Weeds

90306thumbNot many of our favorite plants grow like weeds. We must help most of them along, and give them what they want. A few might naturalize and perform well on their own, but if they do too well and become aggressive or invasive, they too become known as weeds. Although we might prefer some of our favorites to be easier to grow, we are probably fortunate that more do not do too well.

Conversely, not many weeds are appealing plants when they invade our gardens. They might not be so disdainful if they provided fruit, vegetables or flowers, or were less aggressive with other plants. Instead, the conquer and occupy useful space, consume resources, and then toss their seed for the next invading generation. Their aggressive invasiveness is what makes them weeds.

There is no easy definition of ‘weed’. We know them only as unwanted plants, or plants where they are not wanted. Most are exotic (nonnative) plants that were once imported at a time when they were actually desirable. Some were vegetable or flowering plants grown in home gardens. Some were forage crops. Blue gum eucalyptus was imported for wood pulp. A few weeds are native.

Weeds become weeds because they have distinct advantages. Most get an early start at the end of winter, while other plants are still dormant. Then, many weeds bloom and toss seed for the next generation earlier than other plants. Many lack the pathogens of their homelands. Weeds generally survive on less resources, or complete their life cycles before resources are exhausted.

Most weeds are annuals. Many are perennials, Some are shrubby or vining. A few are trees. One commonality is that they should be pulled as soon as they are big enough to get a grip on. They are easier to pull while the soil is moist from winter rain, and before they have dispersed their roots much. Some of the short term annuals are pretty quick and sneaky about dispersing seed too!

Weeds that are woody shrubs, vines or trees need to get pulled like the rest. If merely cut to grade, they will likely regenerate from their stumps, and need to be dug later.