Sweet Alyssum

Sweet alyssum has potential to naturalize.

My neighbor describes sweet alyssum, Lobularia maritima, as a ‘polite’ weed. It naturalized over an area of her vegetable garden that was not in use at the time, but was easy to get rid of when the space was needed for something else. A few plants that were left in the perimeter bloom almost continuously and fill in other unused space between herbs and perennials without interfering with them.

As a bedding planting, sweet alyssum is most often planted from cell packs like most other annuals. Yet, seed is so easy to sow in bare spots among mixed annuals or perennials. Naturalized sweet alysssum sows seed so abundantly that new plants replace old plants before the old plants deteriorate.

Bloom is most often white, but can be shades of pink or purple. However, naturalized sweet alyssum eventually reverts to classic white. The minute, sweetly fragrant flowers form small, round clusters over the delicate mounds of finely textured and sometimes sparse foliage. The tiny leaves are only about an inch long and quite narrow. The largest naturalized plants are not often more than a foot tall.

Gaura

Gaura seems to be a wildflower.

Although not native, gaura, Oenothera lindheimeri, can almost naturalize as if it were. All it needs is occasional watering through summer. It performs better with regular watering. Individual specimens live for only about four years. Some may last for only a single year. However, their abundant progeny are likely to replace and perhaps overwhelm them first.

Gaura prefers sunny and warm exposure. Shade causes sloppy form. Naturalized gaura has potential to become weedy or invade other vegetation. Seedlings relocate efficiently. Cutting back old growth as it deteriorates through winter promotes vibrant spring growth. Concurrent removal of the shabbiest old specimens favors vigorous younger specimens.

Collective growth is mostly less than five feet deep, with wispy and lightly foliated stems. Basal leaves are bigger than tiny upper leaves. Airy flowers are only about an inch wide. Floral color is mostly pale pink. Seedlings of cultivars with white or richer pink bloom are not necessarily true to type. Neither are seedlings of cultivars with richly bronzed foliage. Bloom continues from very early spring until cooler wintry weather.

Hydrangea

Hydrangea have certainly evolved.

Things were simpler decades ago when hydrangeas, Hydrangea macrophylla, were either white or not white. Those that were not white were mostly pink locally because of the alkaline soil of the Santa Clara Valley. Blue hydrangeas where seen where the soil is acidic in the Santa Cruz Mountains, or where the soil was amended to be acidic. (Acidity causes flowers to be blue. Alkalinity causes flowers to be pink.)

Now there are more than five hundred cultivars of hydrangea! Although bloom color is really determined by pH, many cultivars make better blue shades, and many others make better pink shades. Purple and red have been added to the mix, while white has become less common. After getting pruned low while dormant through winter, most hydrangeas grow about three or four feet tall and broad through summer. Some can get twice as large, while many stay low and compact.

Most hydrangeas have ‘mophead’ blooms, which are large, round ‘panicles’ (clusters) of smaller sterile flowers. ‘Lacecap’ blooms are flat topped panicles with narrow borders of the same small sterile flowers surrounding lacy centers of minute fertile flowers. Hydrangeas bloom from early spring late into autumn.

Norway Maple

Most other Norway maples are cultivars.

The botanical name of Norway maple, Acer platanoides, means ‘maple like a sycamore’. It resembles Platanus X acerifolia, which means ‘sycamore with maple foliage’. Platanus X acerifolia is London plane (‘sycamore’), which serves similar purposes. Norway maple lacks the irritating foliar tomentum of London plane. It has more aggressive roots though.

Norway maple was likely never a fad, but was common as a street tree during the 1950s. It naturalized as in invasive exotic species in parts of the Pacific Northwest. It is not such a nuisance locally. Most domestic trees are sterile or almost sterile cultivars. If their roots were more complaisant, they could have been ideal street trees. Their shade is splendid.

‘Schwedleri’, with bronzed foliage, was likely the most popular cultivar originally. Modern cultivars are darker bronze, golden, variegated or simple green. Their deciduous foliage is not so impressive for autumn though. It turns somewhat brownish yellow. The palmate leaves are about five to nine inches wide. Defoliation is efficient. Refoliation is quite late. Not many Norway maples get more than forty feet tall within the mild climates here.

Blackberry

Blackberries are ripening slowly this year because of the mild weather.

Rampant brambles of feral blackberry, Rubus fruticosus, canes are much too common and give blackberries a bad reputation. Yet, with regular selective grooming and pruning, their biennial stems that emerge from woody perennial roots are both more productive and easier to contain than one would guess. ‘Primocanes’ grow rapidly to six to sixteen feet in the first year. In the second year, they become ‘floricanes’, which do not grow longer, but instead develop lateral stems that bloom and fruit. Only a few modern ‘fall bearing’ or ‘everbearing’ cultivars fruit on primocanes.

Canes are trailing, semi-trailing or erect. As the names imply, trailing types like ‘Marion’, ‘Boysen’ and ‘Olallie’, need support. They are the most popular locally because they are more productive. Erect types that need no support, like ‘Navaho’, ‘Choctaw’ and ‘Arapaho’, are less productive, but because they are more tolerant to frost, are more popular where winters are colder. Old classic blackberry varieties are quite prickly. Modern thornless varieties are becoming more popular as more varieties are developed. All have palmately compound leaves with five or seven leaflets. Simple small white or pale pink flowers that bloom late in spring are followed by the familiar blackberries that are ripening now.

Cardinal Flower

Cardinal flower is traditionally cardinal red.

This warm season annual is actually a biennial. Cardinal flower, Lobelia cardinalis, may stay relatively short for its first summer. It might bloom four feet high for its second or third summer. By then, pups are easy to divide as new plants to replace the old. Most cardinal flower plants from nurseries are rather mature. They might grow tall for their first summer.

Common cardinal flower has rich cardinal red bloom and bright green foliage. ‘Alba’ has white bloom. ‘Rosea’ has pink bloom. ‘Queen Victoria’ has familiar rich red bloom above deeply bronzed foliage. Individual flowers are only an inch and a half from top to bottom, but are numerous. Basal leaves can be almost six inches long. Upper leaves are shorter.

Cardinal flower enjoys richly organic soil with regular irrigation. It dislikes getting too dry. It appreciates a bit of partial shade as the weather gets warmest after noon. Seed is easy to collect. However, seed from fancy cultivars is not necessarily true to type. Subsequent generations eventually revert to familiar rich cardinal red bloom and bright green foliage.

Quince

Quince has become a rare fruit.

With the many slender arching trunks, quince, Cydonia oblonga, is more like a large deciduous shrub than a fruit tree. Even old trees are not much more than twenty feet tall and broad. Most of the rare trees that can be found are old, because quince is such an old fashioned fruit. The fruit is still immature and covered with white pubescence (fuzz). By late autumn, it will be remarkably aromatic and resemble golden pears, about four inches long and nearly as wide, and so hard that it should be cooked.

Mexican Fan Palm

Palms are familiar within Californian landscapes.

California fan palm is the only palm that is actually native to remote regions of California. However, Mexican fan palm, Washingtonia robusta, is much more common. Technically, its native range is not far away. It had been the most popular of palms prior to the 1990s. It is more adaptable to more populous climates. Also, it naturalizes within some regions.

Mexican fan palms grow vigorously while young. Growth decelerates with maturity. Very old trees can grow very slowly without completely stagnating. Wild specimens may have potential to survive for a few centuries with such slow growth. Cultivation and irrigation of home gardens may limit this potential. Few local specimens are more than a century old.

Mexican fan palms are taller and slimmer than California fan palms. Their trunks lean as prevailing wind blows them. They easily grow fifty feet tall, and eventually get a hundred feet tall. Such tall and leaning trunks can suspend their canopies over adjacent gardens. Their pleated and palmate leaves are about three feet wide, on petioles with nasty teeth.

Black Walnut

Most black walnuts were not planted intentionally, but grew from the roots of old English walnut trees.

Although native, most local black walnut trees, Juglans hinsdii, are secondary growth from the rootstock of what were once grafted English walnuts, or descendents of such trees. (English walnut trees are grafted onto black walnut understock.) However, the massive old trees that flank the old Monterey Highway south of San Jose were planted as large shade trees nearly a century ago. They are now about sixty feet tall, with lofty broad canopies. Their foot long leaves are pinnately compound, with about eleven to nineteen slightly dentate leaflets that are about three or four inches long. The hard nuts and thick husks are far too messy for refined gardens.

Shasta Daisy

Shasta daisy is ideal for cutting.

Mount Shasta very rarely lacks its snow. Its summit is almost always white. Shasta daisy, Leucanthemum X superbum, strives for the same. Bright white bloom starts in spring and continues into autumn. Primary spring bloom is the most profuse. Sporadic bloom lingers between subsequent minor bloom phases. Only cooling autumn weather inhibits bloom.

Shasta daisy is a resilient perennial. It develops dense colonies of tough basal rhizomes to survive winter dormancy. From spring to autumn, upright blooming stems grow almost three feet high. Individual composite flowers are of classic daisy form with cheery yellow centers. They are excellent as cut flowers, with simple green foliage. Leaves are serrate.

Shasta daisy prefers systematic watering, but can survive with less. It tolerates only a bit of partial shade. Removal of floral stems after bloom or cutting should leave no tall stubs. Removal of all upright growth as it deteriorates into winter promotes tidier spring growth. During winter dormancy, Shasta daisy is very easy to propagate by division of rhizomes.