remarkable plants and fungus
The bird's-nest clubmoss, SelaginelIa lepidophylIa, which is found in North America, can survive for several months without any water. In a drought it rolls up to form a tight ball so as to minimise the area exposed to drying winds and sun; and it turns pale as water is lost from the cells. The plant remains in this state of suspended animation until it is dampened. Then, within about 15 minutes as the water is absorbed, the plant unfurls and becomes green again.
Seeds normally leave their parent plant behind when they are dispersed to a new site. But the rose of jericho, Anastatica hierochuntica, is different. In this plant, which grows in desert regions from Iran to Morocco, the parent travels with the offspring- though the parent dies before it starts the journey. The fruit containing the seeds ripens at the onset of the dry season. As the drought continues, the dying branches curl protectively around the fruit and the roots wither until desert winds blow the plant away. The branches open to release the seeds only when the rains come-by which time the plant may be tens of kilometres from its original site.
The leaves on most plants grow to a maximum size and then stop. But the leaves of Welwitschia mirabilis never stop growing. The plant. which grows in the Namib Desert of southern Africa, consists of a single woody stump and just one pair of leaves, and it takes about 100 years to reach full size.
Throughout that period, the leaves grow constantly. But since the desert winds fray the leaves at their ends almost as fast as they grow, the leaves never get longer than about 2m (7ft). The fraying has a beneficial effect, since the resulting fringes act like nets, collecting droplets of water from the sea mists which roll across the Namib and keeping the plant alive through droughts that can last for years.
So efficient are pines in their reproductive methods that it is quite possible for a pine tree in Scotland to be pollinated by another in Norway, on the other side of the North Sea. Pine pollen is able to travel such huge distances on the wind because each pollen grain is buoyed up by two microscopic balloons.
The Pima Indians, who made their home in the arid regions of the southwestern USA before Europeans arrived, never needed to make water bottles for their journeys across the desert. They simply filled up nat- ural water bottles made by the massive, candelabra- like saguaro cactus. Left to its own devices, the cactus does not produce the bottles. But when the desert-dwelling gila wood- pecker hollows out a nest for itself in the fibrous flesh, the cactus responds by lining the hole with a tough corky layer of tissue, which remains long after the cactus has died and rotted.
The Sphagnum mosses of peat bogs use a battery of natural airguns to disperse the dust-like spores which are their offspring. In the last stages of ripening, the spore capsules shrink to about a quarter of their original size, compressing the air inside, and become shaped like tiny gun barrels, each with its own airtight cap. Each barrel is only about 2mm long. Eventually the cap breaks away and the trapped air escapes with an audible 'pop', firing the packet of spores inside as much as 2m (7ft).
Rattans are the longest, though not the tallest, plants in the world. The tallest are the giant redwoods of California. They grow up to 110m (more than 360ft). But the rattan palm, which winds its way snake-like through trees in the tropics, can be far longer. One Malaysian specimen measured 169m (555ft). The palm climbs up to the highest part ofthe canopy of its native rainforest using cruel, backward-pointing barbs on whip-like extensions of its long leaves. Once a barb has dug into something it is like a fish-hook, extremely difficult to remove. The barbs have earned one South American species the local name oflac/tara, meaning 'The Terrible'.
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