Sunday, May 18, 2014

The Beauties of Belle Isle

A colony of White Trout Lily
(Erythronium albidum)
As a Detroiter, Belle Isle is probably one of the most underrated resources we have here in the city. Almost a resort in its heyday, the island has fallen into disrepair, a circumstance exacerbated by the city's own woes. Recently, it has come under the aegis of state government, which will, hopefully, herald the island's resurgence as a go-to destination - not just for city folk but for all Michigan residents and beyond.

Native Violet (Viola) species
I first really started to get to know the island when my Master Gardener organization (the now-defunct Master Gardeners of Greater Detroit, or "MGGD") used to have their monthly meetings at what used to be referred to as The Belle Isle Nature Center (now known as the Belle Isle Nature Zoo, affiliated with the Detroit Zoo). I also volunteered there for the annual Belle Isle "HUG" ("Help Uncover the Gem") with The Greening of Detroit, planting trees - many of them young saplings grown from seed gathered on the island by naturalist Suzan Campbell.

Cut-leaf Toothwort
(Dentaria laciniata)
Through MGGD, I went on my first Spring Wildflower Walk in a small part of the island near the racquet ball courts - led by Terry Light - in 2005. Nine years later, I led my first wildflower walk for the Detroit Garden Center, in an event the non-profit organization plans to sponsor on an annual basis - and perhaps more frequently, to see the changing of the seasons in this unique habitat. A few days later, I enticed my photographer friend, Don Schulte, for a visit; these photographs are the fruits of that excursion.

Amongst the islands' residents is a small herd of European Fallow Deer - members of an introduced exotic species who had, over time, adapted to the 985-acre park by mutating into a smaller animal. The deer roamed freely over the island, leading to over-browsing and a significant reduction floral species health. In 2004, the deer were penned up; horticulturalists, naturalists and native plant enthusiasts were amazed come 2005 to see the plethora of native plant species that had survived the deers' depredations.

White Trout Lily
(Erythronium albidum)
Singularly, the rare White Trout Lily (Erythronium albidum) was - and continues to be - one of the stars of the show. Less common than its cousin, Yellow Trout Lily (Erythronium americanum), other common names include White Fawn Lily, Dog-tooth Violet and Adder's Tongue. The first two - "Trout Lily" and "Fawn Lily", refer to the speckled leaves, resembling the speckling on native trout or an immature deer. "Dog Tooth Violet" refers to the shape taken by the plant's bulb, which resembles a canine tooth. Finally, after the plant has gone to seed, the pistil still protrudes beyond the seed head, looking like a snake's head with the tongue sticking out.

The Trout Lilies are Spring ephemerals, as are our native Trillium (Trillium spp.), Bloodroot (Sanguinaria spp.), Shooting Star (Dodecatheon spp.) and other woodland natives. Like Mayapple (Podophyllum peltatum), only plants with two leaves will flower; plants with only one leaf do not have sufficient photosynthesis potential to survive the expense of flowering and fruiting. These plants also have a tendency to pull themselves deeper into the ground over time, reducing their flowering potential as greater and greater energy is expended in simply getting above ground; this behavior can be overcome by setting a flat piece of stone eight to twelve inches below grade and then planting above it.

Spring Cress
(Cardamine bulbosa) flowers
Don and I weren't able to do the entire walk. In fact, all of these photos were taken within less than a 50-foot stretch of the entire walk. Other forbs (herbaceous plants that are neither grasses nor ferns) we found included Cutleaf Toothwort (Dentaria laciniata) and what was, at the time, a mystery plant which turned out to be Spring Cress
(Cardamine bulbosa), two members of the cabbage family.

Spring Cress
(Cardamine bulbosa) in situ
Both have delicate, pink, four-petaled flowers - more usually white in both species. The foliage is very different, however, with the Toothwort characterized by strongly dissected leaves arranged around the stem while the Cress has shallowly-palmate leaves arranged oppositely along the stem.

Interestingly, the Toothwort seems more tolerant of drier conditions, finding a home in high, dry areas of the woods, while the Cress prefers low places with Spring inundation. Belle Isle is part of a threatened environment known as "Lake Plain Prairie" - low areas characterized Spring flooding, or "vernal pooling", which dries out with the onset of summer. Plants have evolved various strategies to cope with these circumstances, from heavily-buttressed tree roots to maintain stability in soft Spring soils to ephemerality to take advantage of early season moisture, followed by dry-season dormancy. Many are able to tolerate low-moisture conditions for long periods of time as well.

Spicebush (Lindera benzoin)
Spicebush (Lindera benzoin) is particularly well suited to this environment, such that I often recommend it to clients who experience Spring flooding in their yards. This early season bloomer displays tiny yellow flowers. Like both native and exotic holly species, Spicebush is dioecious, meaning that there are female and male plants and both are required to obtain fruit. Unfortunately, as this plant is not as popular in the trade, it isn't always easy to tell which plants are which; your best bet is to shop in the fall and look for plants with fruit - as those are definitely female; as for those without fruit, you'll have a 50-50 chance it will be male. As with holly, you don't need a one-to-one ratio of male to female - one-to-four should be sufficient - but the plants cannot be too far from one another, so your pollinators can get the job done easily. Its common name derived from the plant's spicy scent (scratch a small area of the bark and take a breath), Spicebush is also one of the larval host plants of the beautiful Spicebush Swallowtail Butterfly (Papilio troilus), the other being Sassafras (Sassafras albidum).

American Black Currant
(Ribes americanum)
Other shrubs in the area include Drummond's Dogwood (Cornus drummondii), a small deciduous tree found on the Great Plains and along the Mississippi as well as the Midwest. Blooming in Summer with clusters of white flowers, similar to those found in the Spring-blooming Redtwig Dogwood (Cornus sericea), it bears small white fruits that ripen August to October, fruits that are utilized by at leasts 40 native bird species. When we visited, this plant was just starting to leaf out but a visit later in the season may favor us with the floral display.

Another important fruit-bearing plant is the American Black Currant (Ribes americanum), which was blooming when we visited the island. Like Spicebush, the flowers are quite tiny and greenish yellow. A member of the gooseberry family, these are small shrubs - up to 4-1/2' in height. The fruits - which make outstanding jams and jellies - are also utilized by native avian species as a desirable food source.

Native Violet (Viola) species
Scattered along the walk were numerous colonies of native violets, similarly-hued but much more desirable than the spreading invasions of Periwinkle (Vinca minor) we saw. Although violets aren't particularly popular with many gardeners, this is generally due to the aggressive, large-leaved, purple-flowering violet despaired of by so many of us. But there are numerous, lovely native violets, including Downy Yellow Violet (Voila pubescens), Canadian White Violet (Viola canadensis), Long-spurred Violet (Viola rostrata) and Common Blue Violet (Viola sororia), which provided a cheerful highlight along - and even in - the asphalt walkway. Despite our mixed reactions to them, Violets are important host plants for native Fritillary butterflies, so their value in the native garden should not be minimized.

Jack-in-the-Pulpit
(Arisaema triphyllum)
Finally, our perennial favorite - Jack-in-the-Pulpit. This native member of the Aroid family - like Eastern Skunk Cabbage (Symplocarpus foetidus) and Green Dragon (Arisaema dracontium) has been in decline along this stretch of the island; whereas nine years ago we saw numerous colonies of many individuals, this year they were much fewer and farther between. It is certain that, as the years pass and effects of the deer continue to abate, the environment will evolve. What used to be primarily large trees and open spaces now has a great deal of shrub cover, mitigating the amount of sunlight reaching the ground and these woodland plants. The effects of the Emerald Ash Borer (Agrilus planipennis) are also visible, with many more snags and downed trees, making passage through parts of the area difficult if not treacherous.

Each year, the environment continues to change, with the ebb and flow of the seasons and the continuing impact of human activity on the island.

All photos copyright to Don Schulte and Notable Greetings.

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