There was some discussion about the differences between the two among my Facebook friends a couple of weeks ago, and I thought I would continue the discussion here, and post a few more photos. By just looking at the bright red fruits, which persist in winter, one cannot easily tell the two species apart, and this has led to some truly ghastly cooking experiments. American highbush cranberry got its common name because its sour fruits can be cooked up with sugar into a sauce that can be used like cranberry sauce. Fruit from the European look-alike cooks up into something that smells and tastes like a distillation of dirty gym lockers. The native American will vary in palatability from plant to plant, so to get the most reliable fruit for cooking it is best to plant named clones, but the native is just not foul-tasting in the manner of European species.

This matters not just to cooks experimenting with colonial recipes. Native North American birds prefer the American species and will leave the nasty, acrid fruit of V. opulus long after they have stripped the fruit from V. trilobum. There have been enough naive or starving birds that have eaten V. opulus (and pooped out the seeds) that the introduced shrub if now found in many wild places. If you are planting a garden and want to provide for the needs of birds, be sure to plant the native. Nurseries often get this one wrong, so there is no help for it, you will want to learn the differences between them and do the botany yourself before you buy.

I’ll get to the field identification in a moment. I want to stress something that is often overlooked: American highbush cranberry has beautiful red fall foliage colour, and this is an asset in the home landscape. In a really good year for colour, V. opulus can turn sort of red-green, so one has to be careful in using leaf colour to do identification. Yet when you see leaves from each species side by side, the difference is striking.

The easiest and most reliable way to distinguish between the two species is to look at the small glands that occur on the leaves just where the petiole (stem) expands into the broad leaf. In American highbush cranberry, these glands are stalked and look like little golf clubs. In V. opulus, the glands are flat, concave, and look a bit like octopus suckers. Leaves are not always typical, so you may have to look at two or three to get a good feel for what that particular shrub is presenting. Once the leaves are gone in the fall, identification is more difficult. Our native shrub will nearly always be found growing in wet, even swampy, places. Also, give the fruits a good sniff before you take them home and cook them; if they smell fetid when bruised, they won’t be improved by cooking.

Viburnum trilobum

Paphiopedilum delenatii. Water soluble coloured pencils, 2011.

Reception for the exhibit will be on Saturday, January, 7th, from 3 pm to 4:30, at Richview Library. I hope to see you there.

Richview Library is located at 1806 Islington Avenue at Summitcrest Drive, north of Eglinton, south of the 401. Lots of free parking in the library parking lot.

.

.

.

.

Installation of the orchid exhibit went smoothly this morning. Many thanks to Liz, Pat, and Mike for all their help.

I am drinking a leisurely coffee, too replete to want even another cookie, and using the Boxing Day respite to think about one of the toughest problems in recommending native plants to replace invasives: ground covers for shade.

An exceptionally blue hepatica.

The standard list of ground covers for shade includes some of the greatest threats to forest biodiversity conventional horticulture offers. And when you come to think about, that’s predictable. Anything that can suppress weeds (one of the great selling points for ground covers) can surely suppress hepaticas and trilliums, and the other choice but slow-growing gems of the forest floor in eastern North America.

Many of the commoner ground-covers are touted as evergreen – think pachysandra, English ivy, periwinkle – and that is part of their appeal to the gardener. In my part of the world, low native evergreen for shade aren’t that plentiful. (There are more choices where the soil is acidic.) However, it eventually becomes clear to the more experienced gardener that the evergreen properties of the standard ground covers are more selling points than fact. In the areas of southern Ontario where snow cover is unpredictable and comes and goes over the winter, the so called evergreen ground covers look pretty darn shabby by March, and you might wish they were decently deciduous so you could clean them up easily. This took years for me to learn, so powerful is the appeal of “evergreen”, and the combined brainwashing effect of wishful thinking, catalogue descriptions, and the accounts of legendary British horticulturalists. A once-a-decade winter where the snow came early and lasted left the snow-protected leaves of, say, European ginger, looking quite acceptable in late winter, and the self-deception was maintained. It took years for me to figure out that the winters that the leaves look good are the winters that you cannot actually see them.

Beyond “evergreen”, the other stumbling block is the use of ground covers in big single species masses. That too is a big part of their appeal. The garden looks intentional and orderly, and one can make a good argument that the visual quietness of a homogenous area sets off specimen plants, or scuplture, and allows the gardener to play with interesting gardenworthy aesthetic effects. Homogeneity also simplifies rote maintenance enormously. The problem in promoting natives for ground covering purposes is that most native forest-floor species live in communities and assemblages, not homogenous masses. Maintaining an assemblage of species requires a knowledgeable gardener; it is not a task one can entrust to a mow-and-blow service. The good news is, if you get the assemblage right for your garden site, your little native mini-community will do a great deal of the maintenance for itself.

Not all of the maintenance though. Stepping back and saying “They are native – they can look after themselves” will quickly leading to the establishment of a thicket of invasive woody saplings. (That’s why they are invasive – they out-compete natives.) So there is no getting around the fact that natives will require more maintenance than the all-smothering standards. However, most of the maintenance should be in the form of knowledgeable attentiveness, not actual work.

A lovely wildflower which forms a low carpet. Do you recognize it?

That said, there are natives one can coax into growing in single-species masses, there are a few evergreen choices for near neutral soils, there are delightful ways of layering spring ephemerals with more lasting companions, and other ways of finding garden worthy substitutes for invasive alien ground covers. I’ll explore a few possibilities in future posts this winter.

Our native roses not only provide fragrant pink flowers in June and bright red hips for wild life, their leaves colour very well in the autumn. One of the best for fall colour is the Virginia wild rose, Rosa virginiana. It has been the most fragrant of the native roses I have grown in my garden, which, beside R. virginiana, have been R. nitida, and R. carolina. It has fine burnished mahogany red stems for colour all winter. Not a dwarf shrub, the Virginia wild rose gets about 6 feet tall and it will sucker rather vigorously in light, sandy soil. Planting it in heavy clay soil curbs its sideways spread but doesn’t seem to harm the plant, but even so, plant it where its arching thorny stems will have a bit of room. Like most roses, it needs more sun than shade. Other than that, it is not at all fussy. It blooms a little later than other species roses, often escaping the worst of the bud worm caterpillars.

Fall foliage of Virginia wild rose, beside a parking lot.

Red hips of Virginia wild rose in garden.

An illustrated catalogue of the exhibit will be posted on here in January.

Golden ragwort (Senecio aureus, syn. Packera aurea), my overlooked and under-used native plant for this post, is a wonderful little flower I would like to see used in many more gardens. I propose it as an alternative to the European garden flower, leopard’s bane. In this case, it is not because the non-native replacee is nasty. Leopard’s bane is not invasive in my area; in fact, I’ve never seen it as a garden escapee. It is just that the native golden ragwort has a role to play as a host plant for insects, is just as pretty, and has no downside as a garden flower. Why not plant the native?

Yellow daisy flowers, in one form or another, are so very abundant in late summer, such an important part of so many plant communities in eastern North America, that any one planting a butterfly or wildlife garden inevitable plants at least a few: towering silphiums, sunflowers, varied and beautiful goldenrods, coreopsis, heleopsis. There are even yellow species of purple coneflowers. The bees and other pollinators of late summer must really like yellow daisies. Yellow daisies are much less common in spring. If one wants a cheerful yellow daisy to combine with tulips, garden centres will readily supply you with leopard’s bane (Doroconium). And that’s about it, at garden centres.

I used to wonder why anyone would want yellow daisies in their spring garden, so closely did I associate them with late summer and autumn. Delicate whites and blues, that’s what I wanted in spring.  Well, that’s nonsense. There are many lovely yellow and bronze tulips, and golden yellow daffodils, and emerging foliage of spireas and bronze-hued young euonymus foliage and other lovely spring things in yellow. A cheerful yellow daisy that grows to about mid-calf might be just the right thing. Golden ragworts flowers are  a bit more golden, individually smaller, than leopard’s bane. The deep purple stems and purple tones to the leaves are a definite asset. In the wild, it grows in moist sites, in ditches and at the edge of ponds. It will grow in ordinary soil in a garden, likes high, dappled shade or morning sun/afternoon shade.

After flowering, the original crown may die out and next year’s growth start on offsets a short distance (only an inch or two) away. Hence, do not deadhead hard until that process is well underway or the whole plant may die. Golden ragwort does not spread beyond its allotted spot in the garden, just shifts around a tiny bit. It will colonize damp spots, to very good effect.

Golden ragwort is a member of the genus Senecio, reputed toxic to herbivores. A scruffy-looking annual European species, common groundsel (Senecio vulgaris), is on noxious weed lists in European countries, because of its reputation for toxicity to horses. Our native Senecios are also full of harsh and bitter alkaloids to discourage herbivory.

Yikes! So, why would anyone want to plant something so unpalatable in a natural, wild-life friendly garden? Well, when plants and plant-eaters have evolved together for a long time, someone will find a way to eat it, by neutralizing or digesting the compounds. And when a species invests so much in utilizing a difficult food source, it often becomes not just possible, but necessary, for it to eat that plant. Just as monarch butterflies rely on milkweeds, there is a little lepidoptera that relies on native ragworts, the northern metalmark (Calephelis borealis). This rare butterfly is a weak flier which usually lives in open rocky areas where it is known to feed on the other native ragworts, round-leaved ragwort and balsam ragwort. The golden ragworts in your garden are unlikely to lure in northern metalmarks. Plant this flower for its bright blooms and enjoy it for its rightness in the landscape. There are doubtlessly other native insects, less studied and less known than the butterflies, which also eat this native.