One of my many half-worked out and not-fully-proven theories is that the golden age of Victorian microscopy coincided with an era when many educated British men were heading off to the colonies and sending back reports of weird and wonderful flora and fauna that they encountered. The microscope was, for those left behind, a similar portal into hitherto unexplored worlds; one that, furthermore, could be found without leaving your own grounds.
A case in point: here is a photograph of some moss on my driveway. I have walked past these mosses thousands of times without giving it a second thought. Today, however, I have a point to prove. The second photograph is a close up of the same moss, taken with the extreme macro lens on my new Olympus TG2 compact camera. This reveals the colonies to consist of tongue-shaped leaves, each terminating in a long hair-like projection. My somewhat dated guide to mosses tells me that these are plants of Bryum capillare. Even at barely a millimetre across, these leaves are enormous compared to the algae I normally write about here.
A row of bright green colonies of Bryum capillare beside my driveway in County Durham, with a lens cap (five cm across) as an indication of scale.
The next step is to strip a few of the leaves off the plants using a pair of forceps and blade and mount these in a drop of water to examine under my high power microscope. Ironically, the lowest magnification lens I have on this microscope (10x) is too powerful and I cannot get all the leaf into a single image, but we can see the hair point as an extension of the “nerve” that extends the length of the leaf. Just visible, too, are the long, narrow cells which form a border around the leaf edge. The cells, themselves, are just a single cell thick, each parallelogram-shaped, about 50 micrometres long and containing a number of small chloroplasts.
I wrote about the tops of boulders being like miniature deserts last year (“Upper Teesdale In March”) and the same applies to man-made habitats such as paths and driveways. The cushion-like growth forms contains networks of tiny spaces which turn the whole plant into a miniature sponge, soaking up and retaining water, enabling it to continue to grow long after the ground around it has dried up. In the past, I presume, mosses such as Bryum capillare would have been rare but, with our modifications to the landscape, including building walls and driveways, we have greatly expanded the habitat available to this species. As a result, our sedentary Victorian naturalist had just as many opportunities to explore deserts as Richard Burton, Charles Montagu Doughty and Wilfred Thesiger.
Bryum capillare. The left hand image is taken with a macro lens; the right hand image was taken under a microscope; the scale bar is 100 micrometres (1/10th of a millimetre). The hair is roughly double the length of the portion included in the image.