Some Exotic Annuals Self Sow

Periwinkle can naturalize a bit too aggressively.

It is impossible to say how long native wildflowers have adorned the natural landscape of California. Various lupines, California poppy and evening primrose had always been the most colorful wildflowers locally until they began to be displaced by exotic (non-native) plants only in the past two centuries or so. Although natives are remarkably resilient to dry summers and occasional wildfires, they are not very competitive with more aggressive and prolific invaders. What the natives and exotics have in common though is that they are so well adapted to local environmental conditions that they are able to perpetuate without much help.

Lupines, poppies and evening primrose, as well as native yarrow, godetia, and fleabane, may unfortunately need a bit of help if exotics want to move into their territory. In areas that are regularly or even only sometimes watered, weeding to remove more aggressive exotic plants helps the natives stay in control. They should otherwise do well on their own. Although without irrigation their growing season is much shorter, natives are slower to be displaced, since so many of the otherwise competitive exotics are not adapted to dry summers.

Many exotic flowering annuals are prolific enough to almost become naturalized, but are not quite aggressive or adaptable enough to get very far from cultivated landscapes. Cosmos, nasturtium, alyssum, catchfly (silene), four o’clock, gaura and foxglove self sow so readily that they are considered by some to be invasive. Some of us instead consider them to be ‘reliable’. They can be useful for unrefined parts of the garden that we do not mind watering, but otherwise do not want to put much effort into.

However, foxglove and even nasturtium can actually become noxious weeds in coastal areas not too far from here. I think that forget-me-not, feverfew, baby tears and English daisy can be problematic anywhere that they get enough water. Also, most annuals eventually revert to more genetically stable forms; which is why all varieties of dwarf nasturtium eventually bloom with the same yellow or orange single flowers. Yet, if we can distinguish between the plants that we can appreciate for their reliability and those that can be too invasive, native and exotic wildflowers and not so wild flowers can make gardening a bit easier.

Mediterranean Climate Is Quite Californian

New Zealand natives perform well here.

“Mediterranean” translates from Latin to “middle of land”. The Mediterranean Sea is in the middle of the land of those who named it. Other regions were either unimportant or unknown to them until the Sixteenth Century. Nowadays, most people of the World are aware of many other regions. A few of such regions also enjoy a Mediterranean climate.

Such climates are obviously not confined to the regions of the Mediterranean Sea. They merely resemble such climates. Some extend eastward into Western Asia. Others are in eastern and southern Africa, southwestern South America and Columbia. Larger regions of such climate are in southern Australia. The closest are here in western North America.

Even these limiting regional designations are debatable. Many horticulturists consider climates of New Zealand to be typical Mediterranean. Such climates are mostly between thirty and forty five degrees north and south. However, some might exist within northern India and southern China. Ultimately, climate is meteorological rather than geographical.

Mediterranean climates receive almost all of their rain during winter. Rain is very minimal through summer. Even if it is twice as abundant in other similar climates, it conforms to a similar schedule. Although winter chill is adequate for many species that need it, frost is mostly minor. Locally, summer weather does not often become too uncomfortably warm.

Native species know what to expect from local climate. So do exotic species from similar climates. Some may prefer more or less winter rain, summer heat or winter chill. Almost all can tolerate warm summers without rain, though. Such weather conditions are normal for them. Therefore, the most adaptable exotic species locally are from similar climates.

This includes species of Eucalyptus, Pittosporum and Callistemon from Australia. Aloe, Agapanthus and Morea are from South Africa. Phormium and Leptospermum are from New Zealand. Oleander and the various species of Lavandula are truly Mediterranean. In the past, a few exotic species adapted too efficiently to become invasively naturalized. Horticulturists are now careful to not import such potentially aggressive species.

Oakland

Oregon white oak, Quercus garryana

Oakland, fifty miles north of here, was named for the oaks that formerly inhabited it. Imagine that! Although valley oak, Quercus lobata, is native, and assumed to be the origin of the regional name, coast live oak, Quercus agrifolia, was likely more abundant there at the time.

Of the many other towns in California with horticultural names, a few are also named for unspecified oaks, including del Rey Oaks, Oakdale, Oakley and Thousand Oaks. Encinitas, Live Oak and the Encino neighborhood of Los Angeles are named more specifically for coast live oak. Paso Robles is named more specifically for valley oak.

Oakland and Oakridge are the only two towns that I could find in Oregon that are named for Oaks. I suspect that Oakland is named for Oregon white oak, Quercus garryana, only because that is the most prominent species of oak there. It is also native here, although I am not aware if I have ever encountered it locally. It resembles small specimens of valley oak, which, incidentally, is also known as California white oak.

This picture of a few main limbs of an exemplary specimen of Oregon white oak is from Cabin Creek Rest Stop on Southbound Highway 5, just north of Oakland in Oregon. To me, it looks sort of Californian, like something that, a long time ago, was more prominent in Oakland here in California, on ‘the Bright Side of the Bay’.

Sky Lupine

Sky lupine grows wild here. (This may actually be arroyo lupine.)

If California poppy were not the State Flower of California, sky lupine, Lupinus nanus, might be. Even though the perfect blue of sky lupine is the opposite of the perfect orange of California poppy, both of these brightly colorful flowers have several similarities, and are often sown together in autumn or winter for their early spring bloom. Both are native to western North America, but are very commonly displaced by exotic (non native) plants. As natives, they can easily self sow if competing specie are controlled. Both are satisfied with annual rainfall. As long as they are not watered too much in poorly draining soils, they are not too discriminating about soil. They do want full sun though.

Sky lupine is an annual that does not get very large, no more than two feet high and half as wide. It seems to be more colorful where it is kept less than a foot high by good sun exposure and wind. The finely textured, palmately compound foliage (divided into smaller leaflets that are arranged in a palmate pattern) gives it width, but only the lower half of its height. The upper half is its narrow spikes of small, neatly arranged ‘pea-shaped’ flowers.

Blue Eyed Grass

It is more like an iris (of the floral sort, not the ocular sort) than a grass.

Contrary to its common name, blue eyed grass, Sisyrinchium bellum, is not a grass at all, but is like a diminutive iris. The modern cultivars that are more commonly found in nurseries are somewhat more colorful than the wild plants that are native to coastal areas between about Santa Barbara and Portland. Yet, even these are rather subdued, with small half inch wide blue or light purple flowers delicately suspended above bluish grassy foliage that may be as low as only a few inches, and is rarely higher than a foot. They bloom best in sunny but not too hot areas. Once established, blue eyed grass is not too demanding, but naturalizes and slowly spreads more reliably if watered occasionally through summer. However, they can rot if watered too generously or too frequently.  

California Black Oak

California black oak defoliates through autumn.

Only a few counties within California lack native California black oak, Quercus kelloggii. Yet, it is not prominent where it is native locally. It generally inhabits mixed forests within the Coastal Ranges. It is rare among home gardens, and rarely available from nurseries. Within the Sierra Nevada, it is common enough to be harvestable as a hardwood timber.

With good exposure, mature California black oaks may get no taller than thirty feet. They can get twice as tall where they must compete with tall trees. The largest trees are higher than a hundred feet. Their elegantly upright trunks are generally less bulky than those of other oaks. Few are more than four feet wide. Gray bark darkens and roughens with age.

The deciduous foliage of California black oak is almost brownish drab green. It becomes brownish yellow prior to defoliation. Cooler weather enhances brighter yellow or orange color, but also accelerates defoliation. Foliage can linger into winter with milder weather. The handsomely lobed leaves are about four inches long, and bigger on vigorous stems. The docile roots are vulnerable to rot with frequent watering.

Sacred Datura

Native sacred datura is extremely toxic.

Georgia O’Keeffe made jimson weed flowers famous. Within the context of her paintings, they seem to be angel’s trumpet flowers. Californians know its species as sacred datura, Datura wrightii. It is as native here as where Georgia O’Keeffe observed and painted it in New Mexico. For refined gardens, though, it is rare. It lives almost exclusively in the wild.

There are a few reasons for this. Sacred datura is a sloppily sprawling perennial that can quickly grow eight feet wide. It is not reliably perennial though. It might perform for only a single season, and then suddenly die. The spectacular flowers close through the middle of the day. Seed capsules are annoyingly bristly. Worst of all, sacred datura is very toxic.

Otherwise, sacred datura is as appealing as Georgia O’Keeffe depicted it to be. Its grand flowers resemble those of angel’s trumpet. They stay open longer during cool and damp weather. Foliar color is creamy white, perhaps with a slight lavender blush. Fragrance is mild only because bloom is so close to the ground. Big specimens can get three feet tall. The foliage has a velvety texture.

From the Muddy Banks of the Wishkah

Well, . . . it is not exactly on the muddy banks.

Kurt Cobain was here. So was I. That is how I got this picture of this English holly in this awkward situation within Kurt Cobain Memorial Park, on the muddy banks of the Wishkah River. I wrote about other pictures from there at my other presently discontinued blog, ‘Felton League’, a bit more than a year and a half ago. This particular picture was omitted because it was irrelevant to that particular post. It is more relevant to this horticultural blog.

‘From the Muddy Banks of the Wishkah’ is, incidentally, the second album that the band Nirvana recorded without Kurt Cobain.

English holly is more naturalized on the muddy banks of the Wishkah River and throughout coastal regions of the Pacific Northwest than it is here. There are not many ecosystems that it can not migrate into there. Here, it can infest only ecosystems that retain sufficient moisture through summer to sustain it, such as riparian or coastal ecosystems. Even within such ecosystems, it would not likely survive on top of a piling such as this specimen.

Some of the most prominent vegetation of the coastal ecosystems of the Pacific Northwest is surprisingly similar to vegetation here. Douglas fir, which is sporadically native here, is the most prominent species within the forests there. Bigleaf maple is likewise more common there than here. Naturalized Himalayan blackberry is even more common and more wicked there!

However, to me, the entire region seemed to be riparian. Nothing was far from some sort of waterway. I encountered nothing that resembled a familiar chaparral ecosystem. Someone who is more familiar with the region could distinguish between the various local ecosystems. I should be more observant about the diversity of the ecosystems and their associated vegetation, both native and exotic, when I return late next winter.

Irrigation Technology Can Get Complicated

Modern irrigation does not age well.

Old fashioned irrigation systems were quite thorough, and technically sustainable. They broadcast generous volumes of water over any vegetation that required it. Their systems were too simple to need much adjustment. Their metallic composition was very resilient. That is why so many old systems were in service for so long. Some continue to function.

However, such old fashioned irrigation systems were not perfect. Their consumption was not as sustainable as their plumbing. They wasted water on vegetation that needed less, and pavement. Some of the broadcast water evaporated before reaching any vegetation. Without automation, old irrigation systems operated when convenient for their operators.

Modern irrigation systems are typically more efficient. Automation allows them to operate prior to sunrise to limit evaporation. Most modern systems apply water directly to the soil. This leaves no irrigation water to evaporate from foliar or other surfaces. Also, it prevents evaporation from airborne broadcast irrigation water. Evaporation innately wastes water.

Of course, modern irrigation systems are no more perfect than old systems. Groundcover and lawns still rely on broadcast irrigation. Such systems still waste water on pavement. Automation can actually waste water if not adjusted manually for rain and other weather. Only the most modern automation adapts to weather. No system responds to vegetation.

Consequently, irrigation can become either deficient or excessive as vegetation matures. Many native species need regular irrigation only as they disperse roots after installation. They are likely to rot with the same irrigation as they mature. Many tropical species need more water as they grow. Some vegetation, as it grows, can obstruct broadcast irrigation.

The complexity of modern irrigation systems complicates their maintenance. Automation is merely one component of the infrastructure. Emitters of drip irrigation sometimes need relocation or replacement. They are sometimes difficult to find below healthy vegetation. Because components are plastic, they are not as durable as old fashioned components.

Punchbowl Godetia

Bloom is brief for wild godetia.

All forty-one species of Clarkia that are native to North America are native to California. Punchbowl godetia, Clarkia bottae, inhabits almost all counties of Southern California. It is absent only from Imperial County. It also inhabits Monterey and San Benito Counties. Its name may allude to its floral shape, or its bloom in Devil’s Punchbowl near Valyermo.

Punchbowl godetia is an ephemeral annual that blooms briefly for spring. Bloom is early in some regions but late in other regions. Also, its schedule is variably from year to year. Because it does not transplant easily, it is rarely available from nurseries. It grows better from seed, which is available online. Within favorable situations, it self sows after bloom.

Bloom is delicate and airy, on limber and lightly foliated stems less than three feet high. Individual flowers are barely an inch wide. Floral color is slightly purplish pink with white centers and tiny red spots. It is variable though, so might be a bit more purplish or lighter pink. Leaves are very narrow. New seedlings do not compete well with other vegetation.