At last, rain. April, till the last few days, had been absolutely dry, March hardly better. Our water barrels were running low, but a whole day of rain on Tuesday, and rain most days since, have filled them. The pond is a couple of inches higher; the garden sighs with relief.
The temperature has dropped, though. Before this spell, we had a week of warm, sunny days. In the pond, this allowed the buildup of filamentous algae. Below the surface, you can see it as streams of pale green filaments, like tresses of hair. On the surface, it forms bubbly masses. This is spirogyra.
I first learnt about spyrogyra at school in biology. Each filament consisting of microscopic, almost transparent box-like cells, connected end to end to make the hair-like fibres. I recall drawing a spirogyra cell as a typical plant cell, and labelling the various items appropriately for a 13 year old: cellulose cell wall enclosing the protoplasm, within which were a nucleus, chloroplasts (containing chlorophyll, to be coloured green), mitochondria which provide energy for the cell, and other organelles (about which nothing more was said). Spirogyra was said to be composed of simple cells. I have learnt since that there’s no such thing as a simple cell.
Cells can be divided into two kinds: prokaryotics and eukaryotics. The former have no nucleus; examples are the countless bacteria which are surprisingly complex. Eukaryotics are cells with a nucleus. It is believed that the first nucleated cells were formed by prokaryotics combining around one and a half billion years ago. This was a revolution in life forms, allowing multi-cellular life to develop. Without this little-heralded event, the plants and animals we know today, ourselves included, would not exist. Sea and land would be the realms of bacteria.
The filamentous algae in our pond is an oxygenator, providing oxygen in the water for the animal life within, such as daphnia, tadpoles, water boatmen, snails, and nymphs of dragonflies and damselflies. The oxygen produced is a by-product of photosynthesis. The other main oxygenator in our pond is hornwort. Plants which have their leaves on or above the surface of the pond, such as water lilies, are not oxygenators. Some filamentous algae, then, is fine, but the problem is it tends to take over the pond and so needs to be thinned out every so often. Not totally, as it provides useful shade for the animal life in the pond.
As the season moves on to mid spring, we are getting more flowers. There are saxifrages in the bed near the container table. They are mostly mountain plants, small and tough, not requiring a lot of watering which is a good thing in our garden. There’s borage here and there, probably an escapee from our wildflower bed, with its droopy blue flowers. If you look closely, you can see they are five-petalled and quite like forget-me-nots which are in the same family, the boraginaceae. The perennial stock near the large birch is flowering on, but looking a little weary.
The cereal project, too, moves on with the season. Sweetcorn and dwarf maize are planted today. The former could grow ‘as high as an elephant’s eye’ but they are only growing in a cardboard box, so hopefully no higher than a donkey’s eye. The dwarf maize will have cobs with multi-coloured seeds, so I look forward to its maturity.