Ancient and ancienter

As you enter the humid warmth of the great Fern House at Kew you are confronted by a huge cycad with snaking trunk and vivid green fern-like leaves. A label proudly announces, "the oldest pot plant in the world", collected in the Eastern Cape, South Africa, in 1773 by Francis Masson and a Kew resident since 1775. Yet two and a quarter centuries are a mere blink when you consider that cycads existed on our planet since before the time of the dinosaurs. Looking at one is like having a magic window into the past.

And you don’t need to travel to Kew to get such reminders. Last summer as I was walking a friend’s dog on the footpath close to Ben Rhydding station I noticed a particularly luxuriant tangle of horsetails along the path side. Horsetails, with their strong system of rhizomes, may be a nuisance to gardeners but they are fascinating to naturalists. Their basic structure comprises a main stem bearing a succession of branches. No leaves - so the important business of photosynthesis has to be done by these green stems: and no flowers (their lineage is much too ancient) - so they reproduce by spores. For this purpose, special stems like fat beige tubes grow from the base of the mature plant, perhaps giving rise to the plant’s Lincolnshire name of Paddy’s pipes. Each 'pipe' carries a conical structure, a cluster of cylindrical capsules that hold the spores. These open up when ripe so the precious grains can disperse to form new plants. In the primeval forests giant horsetails grew alongside huge tree ferns, ancient club mosses and cycads: they, too, are a kind of living fossil.

The only horsetails I recognise are the common ones, but, when I discussed them with our Botany expert, she told me of several other species: the Variegated with its smart brown and green striped stems, the Dutch Horsetail - a naturalised incomer with stems so rich in silica that Dutch housewives used it to scrub pans - and one more. In the ditch that runs along the bottom of Middleton Woods behind the Ilkley Lido there is a fine colony of Giant Horsetail. This handsome plant has a white main stem and green branches, and it grows over five foot tall. I shall certainly go and admire it next season.

Luckily, there are other reminders of the primeval past that can be enjoyed in winter - in fact the slanting winter sunlight shows them to advantage. Our millstone grit carries the fossil imprints of ancient vegetation. There are some good examples on the Chevin, and my special favourite is a large boulder close to a field-gate on the track over Middleton Moor that bears the clear stamp of a section of patterned stem. Seeing it, I get the same dizzying feeling as when I look at the stars through a powerful telescope, only this time it’s the vastness of time which boggles the mind.

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