I’m packing my bags (yet again), this time for another trip to North America. The thought of late summer in the Pacific North West is enticing, but at the same time I hate the thought of missing out on the rock orchids here in Sydney.
This is one of those annoying times of year. From inside the house the garden looks inviting – blue sky, sun, birds, wattles and other flowers, and lots of enjoyable work to do. However, step outside and the cold wind bites, the skies cloud over, rain suddenly arrives, everything loses its charm, and one’s big desire is to get back indoors.
Just at this time of increasing annoyance, the rock orchids burst forth. These glorious, mass-flowering beauties are native to this area. They love living in sandstone. They don’t ask for a lot of sun, they’re happy enough in shade. They don’t ask for a lot of nutrients, they grow on rocks. They don’t demand much at all, and yet they manage this annual abundance of glorious flowers. When I get annoyed, I think of these orchids: how they thrive amongst the stones, and bring blessings of beauty to everyone who has ever wondered if winter would ever end!
Yesterday I was hit by a terrible thought: what if there were no more rock orchids on earth? In truth, these beautiful plants are not threatened, although their numbers in the wild are down because habitat is depleted. I wasn’t hit by fear for orchids, exactly. Rather I was jolted by that crushing realisation that we are living amongst terrible losses. The losses are cascading and we don’t know where, or if, they will stop. Almost anything could be at risk; most probably almost everything is at risk. I went rushing off to the native garden to see if the orchids were blooming yet, as they always come out first over there.
One of my former research colleagues, the late Frank Fenner, predicted that in a hundred years or so the human species will have driven itself to extinction. His views are extreme, but they touch on this crucial point: we are driving the earth into greater and greater loss of ecosystems; we are stimulating extinction cascades that are expanding rapidly and in many cases unstoppably and unpredictably; we are producing the most extravagant amounts of toxins, garbage and waste; and we are consuming and wasting all that lives in the most careless fashion. Whether the world goes on with us or without us, it will be a world radically disfigured by us. The kind of time that it will take for the earth to recover diversity and stability is beyond our comprehension.
Often when trying to think about what seems unthinkable I have to remind myself that answers to big questions about life do not arise from one species alone. Our lives are held within sustaining webs of life, and all our philosophy, and all our action, and all our desires unfold most effectively when we pay attention to the others.
We humans are not alone here on earth. Other creatures are in these same webs: there are no other webs.
For today I am turning to rock orchids and wondering about their lives. I don’t want to extract a moral lesson, or turn them into an allegory. I just want to cherish them more deeply by understanding them better. And what a story their lives tell!
In my area the main rock orchids are Dendrobium species: the yellow D. speciosum and the ‘pink rock orchid’ D. kingianum. They are lithophytes meaning that they live on rocks: their long aerial roots find crevices both to hold on to and from which to access nutrients.
These are very low nutrient creatures; they get their main sustenance from air, rain, debris and their own dead tissue. Some of what they glean they store in ‘pseudobulbs’ as a hedge against hard times, particularly dry spells. The rock orchids themselves provide habitat for others – fungi of course, and also animals and bacteria. They are home to a beetle known as the Dendrobium beetle. The stems are edible; they were eaten by Aboriginal people and are opportunistically browsed by other plant eaters.
Another side of this low nutrient story is the strong symbiotic mutualism they share with a microscopic fungus. This mutually beneficial relationship is known as a mycorrhiza. Orchid and fungus are not parasitic on each other, since both seem to flourish, but the best known fact seems to be that orchids simply could not live and reproduce without their fungi. In fact, orchid seeds are so low in nutrients that they cannot germinate without the help of these symbionts who supply the developing plant with nutrients until it is able to photosynthesize. Given the cycles of drought that characterise Australia’s ENSO-driven climate, new generations of rock orchids may have long periods of dependency.
Yet another side of this story is orchids’ relationship with pollinators. This is not symbiotic, at least as far as is now known. Botanists talk about lures and rewards: angiosperms invite or lure others through their dazzling brilliance of colour, scent and shape, and they ‘reward’ their visitors with nutrients. Rock orchids are among the tricksters in the world of lures and rewards. They produce great, showy, masses of flowers, and when the sun shines their fragrance comes forth.
Orchids offer up all the signs that send forth the great angiosperm message: ‘nectar’. This is explained in delightfully technical language by two orchid scientists:
‘Potential pollinators of Dendrobium speciosum are attracted to the plant by large, cream to yellow, finely segmented, aromatic inflorescences. Plants in natural populations flower synchronously, producing a massive display. Osmophores scattered over the perianth produce a strong, sweet scent in sunny weather. Nectar-seeking insects are guided to the central, reproductive area of the flower by the colour gradation of the perianth, including an area of high U.V. reflection near the centre, and a bright yellow ridge along the labellum. A tube formed by the labellum and column directs the potential pollinators.’
In the words of these scientists, this glorious invitation is akin to ‘false advertising’.
The pollinators (mainly bees) come and do the work of pollination, but they get no reward because in spite of all the showy appearance there is no nectar. Unlike the mistletoes I discussed in an earlier essay that get on in the world though abundant and promiscuous generosity, rock orchids get on through targeted deception.
These brilliant tricksters have developed fabulously enticing beauty. The human fascination with orchids is just as keen (I imagine) as that of bees. And yet the delicacy of the flowers is part of an extremely successful adaptation to harsh conditions. Their way of life is anchored at the edge of the nutrient world and is adapted to many extremes. From 45° heat in summer (115F) to winter frosts, through winds, droughts, bushfires and deluges, rock orchids hold on in their stony bastions and put forth great masses of flowers year after year except when recovering from bushfires. The great confederacy of Orchidaceae has been around for perhaps 130 million years, and the orchids here in Sydney are probably much the same as their direct ancestors who were here with the dinosaurs.
The diversity of their interactions is captivating: they are food for some creatures, including humans; they are symbionts with others. And then they are tricksters with yet others! Symbiotic, delicate, tough, fragrant and with great survival strategies, their multispecies complexities testify to the diversity of interactions that are woven into the webs of life.
All praise to orchids ~ Every leaf, every stem, every tough little kiss of life.
© Deborah Bird Rose (2014)
Frank Fenner’s article (view here)
On symbiotic mutualism between orchids and fungi, see ‘hunter valley backyard nature’
On ‘false advertising’, see ‘The Pollination Biology of Dendrobium speciosum Smith: a Case of False Advertising?’ by AT Slater and DM Calder, published in the Australian Journal of Botany 36(2) 145 – 158, 1988.