Chilean Nightshade

Chilean nightshade is less aggressive than related potato vine.

Yellow centered blue flowers like those of the familiar potato bush, on vines almost like those of the comparably familiar potato vine would be like the not so common Chilean nightshade, Solanum crispum. However, Chilean nightshade needs to be trained onto support in order to climb, and only reaches fifteen feet or so. The cultivar (cultivated variety) ‘Album’ is like a shrubbier redundancy to potato vine, since it has white flowers. ‘Glasnevin’ is the most popular cultivar because it flowers freely and is hardier to frost.

The nearly inch wide and slightly fragrant flowers bloom in small clusters from May or June until about now. Small but sometimes prominent green berries that turn yellowish orange and then dark purple are toxic. Partial shade inhibits bloom and vigor.

Foxglove

Foxglove is the source of digitalis.

It is no coincidence that its generic name seems more pharmaceutical than horticultural. After all, the cardiac medication digitalis is an extract of foxglove, Digitalis purpurea. The plant is unfortunately very toxic. Because it naturalizes in several regions, it can be more hazardous than standardized medications. It can migrate undetected into home gardens.

Otherwise, foxglove is a delightful warm season annual with a rustic or woodsy style. It is actually a biennial that generates basal foliar rosettes during its first season, and blooms during its second season. Although technically monocarpic (so should die after bloom), it can produce a few short pups to bloom later. Seedlings can appear in random situations.

Plants from nurseries grew during a previous season, so are ready to bloom immediately for early summer. Their seedlings may grow through later summer and autumn, so might bloom for the following summer. Floral stalks generally stand between three and six feet tall. The tubular and somewhat pendant flowers are mostly pinkish purple, pink or white. A few modern varieties bloom yellow or apricot.

Toxic Plants In Home Gardens

Even toxic plants have their attributes.

Oleander that inhabits freeway medians is poisonous enough to be hazardous. Two tons of Buick cruising at sixty-five miles per hour past such oleander has more potential to be hazardous. The risk associated with toxic plants within freeway medians is as limited as their accessibility. Remarkably durable and resilient oleander is therefore quite practical.

Realistically, established oleander is quite practical for many landscapes. (Oleander leaf scorch limits the practicality of new installation though.) It is not the sort of vegetation that is appealing for consumption. Caustic sap should deter anyone who tries. It is poisonous primarily to curious young children or chewing dogs. It is generally safe in their absence.

Foxglove, angel’s trumpet, castor bean, nightshade and poison hemlock are significantly more hazardous because they are easier to consume. The seeds of castor bean and the fruits of nightshade actually seem to be edible. Poison hemlock sometimes mingles with foraged greens. Many diverse toxic plants exhibit hazardously appealing characteristics.

Some toxic plants are appealing enough to come indoors, where cats who never venture outdoors might take an interest in them. Dumb cane (Dieffenbachia) is a popular but very toxic houseplant. Mistletoe, although a parasitic and undesirable weed, is popular as cut foliage at Christmas. Its berries are very toxic. Poinsettia exudes caustic sap if disturbed.

Some toxic plants are toxic only because they are allergens. They affect only those who are allergic to them. Most people are allergic to poison oak. Fewer are allergic to related plants, such as African sumac. Some people are more or less allergic to a few species of Grevillea or Primula. Reaction to such species can be comparable to that of poison oak.

Too many toxic plants inhabit home gardens to list. Some are familiar fruit and vegetable plants, such as elderberry and potato. Some should be removed for the safety of children or pets. Selection of new plants can simply and conveniently omit any concerningly toxic plants. Generally though, with responsible interaction, most toxic plants are not too risky.

Oleander

Oleander, although pretty, is famously toxic.

Prior to the appearance of oleander scorch disease in the early 1990s, oleander, Nerium oleander, was almost too popular, and for good reason. It is remarkably resilient to harsh conditions. It had been one of the more common plants within freeway landscapes since freeways were invented. Now, new plants are rarely available. Only older plants remain.

White, pink or red bloom is most abundant through warm summer weather, with sporadic bloom continuing through most of the year. Some dwarf cultivars bloom with peachy pink double flowers. Plants with enough room to grow wild without much pruning bloom best. Frequent shearing deprives the healthiest oleander of its blooming stems prior to bloom.

The biggest oleander get as tall as fifteen feet, so can be pruned up as small trees, either on single trunks or multiple trunks. However, because their limber trunks can not support much weight, occasional pruning is necessary while trunks develop. Such pruning limits bloom, so should happen mostly at the end of winter. Straight single trunks need staking. Oleander wants warm and sunny exposure, but is quite undemanding.

Be Careful With Toxic Plants

Toxic plants can be quite appealing.

Plants are so much more intelligent than they get credit for. Many use color, fragrance and flavorful nectar to get insects and animals to disperse their pollen for them. Some provide fruit for animals that inadvertently take and disperse their seeds. Others use barbs or sticky substances to attach their seeds to unknowing animals that take them away. Plants have all sorts of techniques for exploiting those who are more animated than they are. After all, immobility has certain disadvantages.

Because plants can not get away from the animals and insects that eat them, many have developed techniques for being unappealing. Plants that live in deserts where edible foliage is relatively scarce are famous for their nasty thorns and spines, like those of cacti and agave. Hellebore and poinsettia have caustic sap that make them unpalatable. The naturally aromatic foliage of many edible herbs, like rosemary and lavender, is actually intended to repel grazing animals with sensitive noses.

Some plants unfortunately rely on toxicity for protection. Many plants are only partially toxic. For example, apples are intended to be eaten safely by animals that disperse the seeds within, but their seeds are toxic enough to avoid getting eaten by rodents after dispersal. Potato, tomato, rhubarb, asparagus and elderberry plants all produce edible fruits or vegetables, but also have poisonous parts. Some edible fruits and vegetables, like grapes and onions, are edible to humans, but toxic to dogs.

Foxglove, angels’ trumpet, morning glory, yew, rhododendron, azalea, oleander and castor bean are some of the more notably toxic plants often found in home gardens. Wisteria, holly and ivy produce toxic seeds and fruits. Dieffenbachia is a popular but very toxic houseplant. Although mostly safe, toxic plants can be a problem where young children might put things into their mouths, or where puppies are in that chewing phase.

Some Edible Plants Start Out Toxic

41126thumb
Pokeweed is both edible and toxic.

Early American settlers from Europe had a lot to learn about the plants of North America. After their first harsh winter without much food, many were eager to eat the first fresh greens of spring, which was sometimes the very poisonous jimson weed. Those who were not lethally poisoned right away might have hallucinated and told their friends that they could fly, and consequently got burned as witches.

It should be no wonder that some early Americans were hesitant to try tomatoes, which are related to jimson weed. Potatoes are also related, and their fruit, foliage and stems actually are toxic. Pokeweed (unrelated) was probably riskier, since the same young shoots that can be cooked as greens become toxic as they mature. Their poisonous berries, which were used as ink back then, look delicious.

There were other potentially dangerous edibles brought from Europe and other places as well. Rhubarb, which makes such great pies, is petioles (leaf stalks) for toxic leaves. Both American and European elderberries are slightly toxic before getting cooked into jelly or pie. Elderberry juice must be cooked and then given yeast to make wine. Figs and mulberries can be eaten right off their trees, but their sap is caustic enough to be irritating to the skin.

The seeds of apples, pears, peaches, nectarines and apricots can be toxic if too many are eaten. They are not a problem only because they are not eaten. However, apricot kernels can be roasted and eaten like almonds because the cooking process denatures the toxins. Separating the small kernels from the hard shells is much more work than it is for almonds, but they supposedly have great flavor.

Just like for apricot kernels, pokeweed and elderberries, the heat of cooking makes taro edible. The foliage can be eaten as stewed greens. The big and starchy corms (bulb-like stems) are something like potatoes. All parts of taro are toxic while raw. There are actually a few toxic plants that are edible once cooked. For a few others, it is important to know what parts are edible, and what parts are toxic.

Poison Oak Tree

P91229From below, this looks like a shrubby deciduous tree. It is really just a Douglas fir, like those around it. All the defoliated thicket growth is overgrown poison oak. It has likely been climbing the fir tree since it was quite young. Poison oak is not very proficient at climbing bare trunks. It typically climbs into lower limbs, and then into higher limbs before the lower limbs are shed.

No one has bothered to cut this poison oak out of the fir tree because it is not within a landscapes area. That dark margin at the top of the picture is the underside of a bridge, from which, not much of the thicket growth below is visible. The area from which this picture was taken is used for piling greenwaste and parking, where no one is concerned about wild vegetation beyond.

However, now that I sometimes park in that particular parking area, I am finding this mess of poison oak difficult to ignore. There was a similar but even bigger thicket of poison oak up in a redwood tree at the farm, from where it tossed seed into horticultural commodities below. The resulting seedlings added a whole new dimension to weeding the stock. The thicket had to go.

The problem with the thicket in the picture above, although not as serious, is that it too tosses seed into area where people work. Seedlings are likely to grow where greenwaste is processed, and where I sometimes park. Poison oak that grows on the far side of this fir grove will be uncomfortably close to the right field foul line of a ball field that will eventually be restored there.

I have no intention of cutting the poison out of the fir tree. I will merely sever the main trunk at the base, as seen in the picture below. As it deteriorates over several years, no one will mind if it is somewhat unsightly on the industrial yard side. The adjacent fir trees sufficiently obscure it from view from the ball field side. The priority will be preventing seed from proliferating.P91229+

Rhus diversiloba / Toxicodendron diversilobum

P81209This would be a good topic for one of my rants on Wednesday, except that it is too silly for that.

Many years ago, before I started writing my gardening column for our local newspapers, my colleague Brent and I used to exchange funny newspaper gardening articles. Some were obviously not written for local climates. Some were just very inaccurate. Back then, it was done by mail, so the articles were added to anything that we happened to be sending to each other at the time. If I sent him some seeds, I would add an article or a few from the San Jose Mercury News. If he sent my cuttings, he would add an article or a few from the Los Angeles Times. They eventually became the inspiration for my gardening column, when Brent and others told me that rather than making fun of the inaccuracies of the articles, I should provide accurate articles.

One of the silliest that Brent sent to me was an otherwise well written article about star jasmine. Most of the information about it was accurate, until it got to describing the colors of the exclusively white bloom. The article explained that star jasmine bloomed in vivid shades or blue, purple, red, orange and yellow; just about every color except for white!

Well, I topped that with an article about protecting Japanese maples from theft, which sounded crazy even before reading the article. There were three recommendations. The first was to surround the subject Japanese maple with razor wire. Ah, the ambiance! The second recommendation was to dig a hole about as big as a trash can and fill it with concrete with a curved piece of rebar to make an enclosed loop on top, and then chain the subject Japanese maple to it. How about we just do without a Japanese maple in the front yard in a neighborhood where we expect it to get stolen. The third recommendation was to plant poison oak around the subject Japanese maple. Yes, good old fashioned poison oak, Rhus diversiloba, which is also known by the more descriptive Latin name of Toxicodendron diversilobum, and commonly available at . . . . some nursery . . . . somewhere. . . . You know, one of those . . . . garden centers . . . . or something.

Silly? Yes! What is sillier is that poison oak really IS available from certain nurseries that sell native species! What is even SILLIER than that incredible degree of SILLINESS is that one of the so-called landscape companies that I worked for in about 2006 actually procured some for habitat restoration outside of, but adjacent to a newly landscaped area on the banks of where the Guadalupe River flows through San Jose. Poison oak and other native vegetation needed to be eradicated for the installation of the new poison oak and associated irrigation system, because nothing is more natural than supplemental irrigation! Then, the ‘gardeners’ had to conduct regularly scheduled weed abatement so that poison oak growing from seed tossed by the pre-existing poison oak did not grow up and compete with the new poison oak in the new ‘natural’ ‘landscape’. We certainly would not want poison oak taking over the poison oak.

Okay, this is not Wednesday, so I will finish this rant.

Poison oak happens to provide some of the best orange and red autumn foliar color in our region where almost all of such color is simple yellow. Where it is out of the way and not bothering anyone, it is sometimes left to climb high into trees, where it colors almost as well as flowering pear. Yes, it is pretty, but I will not be planting any of it.P81209+