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By Root 723 0

I had thought to be a unique marvel. In an hour small silvery bubbles (oxygen) formed on the submerged moss—it was respiring; it was alive. I put a sample of the moss back on the rock, where it again dried, more quickly than the clothes we put out on our clothesline. I then collected samples of five other species of moss from our woods. I dried and then wetted them at intervals of months. They froze outside in the winter, and then I brought them in again to dry out. I let a portion of them stay almost totally dry for six months, and when I dunked them in water they again soaked up water in seconds, and then looked as fresh and green as when I had picked them. I did the same with three species of club mosses (Lycopodium digitatum, L. clavatum, and L. obscurum). They all died when they dried, and once they dried, it was difficult to get them to absorb water. For a further contrast with real moss, I picked eight kinds of green herbs and let them dry. After a week the dried leaves looked a dull green, but when wetted (with difficulty) they were black and dead.

In mid-November, while I was up in a balsam fir tree in Maine, sometimes for hours at a time, I had further opportunity to admire the miracle of mosses. Right next to me on the limb where I was perched, I counted at least three species each of mosses, growing in part intermingled with as many species of lichens. Every limb was loaded with both, as were those of the neighboring trees. The ground beneath me was covered with already browning fallen leaves, but the rocks that poked out among them were covered with vibrant, luminous green cushions of moss in moist areas, and with lichens in more dry and exposed areas.

The lichens from the branches dried as quickly as moss. They also absorbed water as quickly, and then they seemed as vibrant as any in spring and fall, when they are normally wet all the time. The water-absorbing property of moss is of course well known, and sphagnum moss, especially, is a traditional diaper material used by northern peoples. In their deathlike state lichens are protected by several antibiotic chemicals, should any microbes attempt to consume them. Lichens are a cooperative association of a fungus and an alga, in which the alga provides carbohydrate for the fungus, and the fungus provides minerals and shelter for the alga. The summer had revealed common marvels, which I had seen before but not noticed. They remind me of the resurrection fern of the Namib, but another unique plant from there, the two-leafed Welwitschia mirabilis, is in a category by itself.

WELWITSCHIA IS NAMED AFTER FREDERICK MARTIN JOSEPH Welwitsch, an Austrian medic, naturalist, and collector who first found it in Angola on 3 September 1859, the year that Charles Darwin published On the Origin of Species by Means of Natural Selection. This plant resembles no others, and its evolutionary origin is still an enigma. It is the sole representative of its genus and the sole species within its plant family. Its Latin species name, mirabilis, means unique or wonderful. The Afrikaners of South Africa also call it Tweedlaarkanniedood (literally, “two-leaved-cannot-die”). This plant is also radically different physiologically from all other desert plants; its two huge leaves stay green and hydrated continuously, and it may live more than 1,000 and possibly 2,000 years.

Fig. 34. Welwitschia plant, a unique denizen of the Namib Desert that does not shed its leaves as most other plants do, and that stays hydrated when others dry out. It has two lifelong leaves that may grow (as they fray) for more than 1,000 years.

Other plants adapt to extreme heat and drought by having no leaves, or small leaves that are shed when water becomes scarce. Welwitschia mirabilis has two straplike leaves that are more than a yard in diameter and several yards long, and they are never shed. Like hair, they just keep growing from the base, and gradually wear off or disintegrate at the end. The functional (living) part of the leaf may be up to seventy years old and earns the distinction of being the oldest