Journal Number 88
September 2003

CANADIAN NOTES

The Joy of Discovery: Wondering Why
By Marilyn H S Light, Ottawa

I often wonder why I study orchids. Is it because they are relatively uncommon and therefore all that more exciting to discover? Is it because many orchids have incredibly tiny yet complex flowers or is it because they all lead such complex lives? Is it because I need the tonic of wildness, an intriguing scent upon the breeze, a flash of colour, or a close yet tenuous relationship with an ephemeral creature? It may be for any or all of those reasons but I know that I was somehow "hooked" by orchids from the first time I learned what they were.

My first experience was with the Yellow Lady's-slipper (Cypripedium parviflorum var. pubescens) that I found blooming in a forest about to be cut down to make way for housing. I was twelve years old then and distinctly remember thinking about those who would never have the same opportunity to discover the beauties of nature in this soon to be destroyed woodland.

A later experience was with tropical orchids growing in the university greenhouse. I still have those memories stored as photographic images of an un-named and aphid-infested Epidendrum and of the fading rose-pink bloom of a Sobralia. Comparing what I viewed then to what I have since seen growing in the tropics, the flowers and plants now seem rather ordinary... but they were orchids and therefore something to be examined closely.

Recently, I visited Costa Rica where I had the opportunity to walk a rainforest trail in Tapanti National Park. There were not many orchids in flower but the riot of epiphytic growth was fascinating. I could lose myself while closely examining a moss-covered limb for the telltale signs of orchid plants. I was delighted to identify an Elleanthus aurantiacus simply by its foliage and brilliant orange buds. I realised that it is not just the flowers that intrigue me so much but the plants themselves and the way they live. Apparently, this Elleanthus is often the first orchid to re-inhabit slopes exposed to volcanic action. I wonder why?

The genus Spiranthes is fascinating for several reasons. The common name of this pan-temperategenus, Ladies' tresses, suggests something dainty yet elegant, geometric spirals to intrigue the observer. The Northern Slender Ladies' tresses, Spiranthes lacera var. lacera, is delightful in bloom. Scented and incredibly crystalline white blooms spiral about a central axis (Fig.1). Close examination of the flowers reveals their emerald throats. I have come across these orchids mostly by chance: they are never very common and plants not that long-lived. I happened upon the pictured plant and a few others while picking wild raspberries in the forest north of Ottawa.

Several plants were growing in the shrubbery along a recently opened bush road. One has to admire the orchid for taking quick advantage of favourable habitat created just three years earlier. Another species, Case's Ladies' tresses, S. casei, is yellowish-flowered, somewhat coarse and longer-lived but confined to areas of acidic sandstone at least in the Ottawa area.

I have found other Spiranthes growing along the Ottawa River shoreline (Fig. 2). In spring, when the winter ice melts and rushes downstream, the shoreline is scoured by giant ice blocks and swift currents. Species such as the diminutive Shining Ladies' tresses, Spiranthes lucida, survive as rosettes nestled between shoreline rocks and anchored by their finger-like tuberous roots. When the waters subside, the leaves expand followed by stems of tiny butter yellow-Iipped white flowers.

The Nodding Ladies' tresses, Spiranthes cernua, and the Hooded Ladies' tresses, S. romanzoffiana, can grow in large colonies of hundreds to thousands of plants. The latter species is especially widespread from east to west and has even been found along the coast of the British Isles where it perhaps arrived as errant seeds.

Some members of the genus Spiranthes can be good colonisers. Spiranthes cernua is polyploid, pollinator-independent and able to produce embryos without the need for fertilisation through a process called apomixis. It has been suggested that such orchids may have a wider adaptability than their diploid counterparts, especially in disturbed habitats, perhaps because of their ability to produce large numbers of "seeds".

Why then do these populations disappear when the disturbance subsides? Large colonies can be short-lived, flourishing for a time after soil has been disturbed then vanishing as if they had never existed but other colonies persist for many years. I know of a group of S. cernua perennially inhabiting a large lawn. The owner does have to cooperate and not mow the developing inflorescences but since this orchid flowers in autumn at a time when grass grows slowly, it likely is a welcome respite from work for the gardener who has an opportunity to sit back and enjoy the sparkling white, sweet-scented flowers instead.

The best way to us conserve orchids poses a vast range of questions for which we still have relatively few answers. Some conservation initiatives are designed to maintain populations in nature but how can we maintain species that depend upon occasional disturbance events such as extreme weather or volcanic action?

Obviously for some species, occasional mild disturbance like mowing works well but for others, the most appropriate strategy is not so easily grasped. For these species, we need space, preserves, parks, unmanaged large places where natural disturbances are chance events. Following the behaviour of individuals and populations through long term study will hopefully reveal specific conservation strategies to deal with recovery after extreme events.

I hope always to be wondering why and I hope that orchids will persist so there will always be some unique features to be discovered by future generations.