Can the Centennial Orchid live 100 years? Wrong, it can actually live 2,000 years!

In 1859, Austrian botanist Frederich Welwitsch discovered a strange plant in Cape Negro, Angola, Africa: it was like an octopus, curled up in the sand, with a low cork trunk, and looked very old. Although Welwitsch didn't know what it was, he was shocked. The following year, when botanists from the Linnean Society of London described this new species, they naturally used the name "Welwitschia mirabilis" when describing it. It is the Welwitschia mirabilis.

Welwitschia and its inhospitable habitat, from The natural history of plants, their forms, growth, reproduction, and distribution | Wikimedia Commons

The headless tree in the desert

Wild Welwitschia orchids are found only in the Namib Desert along the coast of Angola and Namibia. They are extremely long-lived and slow-growing plants. How many years old are they? Researchers used carbon 14 dating to measure two relatively small plants and found that they were about 500 to 600 years old. It is estimated that the larger plants may be 2,000 to 3,000 years old.

Two photos taken from the same location and angle in Namibia in 1884 and 2016. | Observatory Welwitschia Vlakte (A09)

The fact that makes people's SAN value drop wildly is that the Welwitschia has only two leaves that grow continuously throughout its life. There is meristem at the base of the leaves that continuously divides new cells. During the growth process, it is torn by various external forces, and then it splits into this horrible appearance in the wild (imagine noodles passing through a noodle cutter). As the cells, which can live for up to ten years, die, the leaf tips will wither and hang there dryly.

This 100-year-old orchid in the Beijing Botanical Garden of the Chinese Academy of Sciences looks young (maybe older than you...), who didn't have twin ponytails when they were young? | Purple Sandpiper

In the past, people believed that the leaves of the Welwitschia were two cotyledons that remained young. Later, artificial cultivation and anatomical research overturned the cotyledon hypothesis, and instead believed that it was because the apical meristem had no chance to develop and remained active as lateral buds. Well, from the Tianshan Child-like Grandma to the Headless Senior Sister.

Someone measured the growth of Welwitschia between 1985 and 1998 and found that the leaves grew an average of 0.37 mm per day, with the growth rate mainly varying with air humidity and precipitation. If the midsummer rainfall exceeded 11 mm, the growth rate would triple.

Hard times

Welwitschia photosynthesizes during the day, which seems to be a "suicidal" behavior. The annual precipitation in the Namib Desert is only 2 to 200 mm. The broad leaves in the desert can evaporate one liter of water a day. Maybe the stomata of the Welwitschia leaves can absorb water condensed from fog? But anatomy does not support this hypothesis, and the leaf growth rate has little to do with the distance from the coast. It may just be that the sea fog from the Atlantic condenses on the ground and is then absorbed by the roots of the Welwitschia.

As research progressed, people discovered that Welwitschia can store the carbon dioxide it absorbs at night as crassulacean acid, so that it does not need to open its stomata to perform light reactions during the day. This water-saving skill commonly used by succulents - crassulacean acid metabolism (CAM) - is also found in Welwitschia, but it seems that it is not often used, so it has not been found in previous observations, which is quite puzzling.

Welwitschia in the Namibian desert | Ragnhild & Neil Crawford / Wikimedia Common

Underground, the simple taproot of the Welwitschia plant is connected to four mycorrhizae (symbiotic associations between plant roots and fungi) and is connected to the mycorrhizal network of two grasses in the Namib Desert. Although they can survive without mycorrhizae, they obviously grow better in places with grasses and mycorrhizae. In some areas of the Namib Desert, the Welwitschia plant has even become the dominant species among perennial plants.

A relative of the pine tree?

Where did the Welwitschia come from? It comes from a monotypic family and a monotypic genus, so it can be said to be "unrelated", but its Gnetales order has spread to many corners of the world, such as the genus Ephedra, which has medicinal value.

Tibetan ephedra (Ephedra saxatilis) on the roadside in Guyu Township, Zayu County, Tibet, is a plant of the order Gnetales, just like the Welwitschia. | Purple Sandpiper

Comparing the reproductive organs of the two plants above, we can infer that they are related. Well, they were one family as early as the Jurassic period. There is another branch of the order Gnetales, which looks more like a "normal" vine, shrub, or small tree. Angiosperms with fruits enclosing seeds occupy the vast majority of tropical forests, but Gnetaceae is just a high imitation. The part that looks like a red fruit is the aril developed from the false perianth outside the ovule, and there is no strict ovary structure.

Not only are they similar in appearance, the tissues that transport water in Gnetales are different from the tracheids of other gymnosperms, and have vessels similar to those of angiosperms. Although they seem to be imitating each other everywhere, the Gnetales appeared one geological era earlier than the angiosperms that dominate today.

Female Gnetum gnemon | gbohne / Wikimedia Commons

For a long time in the last century, people believed that the ancestors of angiosperms evolved in the Gnetales. However, as more and more genes were sequenced, most evidence pointed to the Gnetales as the sister group of the Pinaceae: that is, the relationship between cypress and pine is not as close as that between Welwitschia and pine, and angiosperms are definitely not descendants or sisters of the Gnetales.

Welwitschia is dioecious. The female and male reproductive organs of gymnosperms are called megaspores and microspore cones respectively, but here we will just call them cones. The cones of Welwitschia really look a bit like those of pine trees, especially fir trees. Its seeds also have small wings and are also spread by the wind. One plant can produce tens of thousands of seeds. However, its pollen is insect-pollinated.

Female Welwitschia in Rama IX Royal Park in Bangkok. It is rare to see it in breeding season | Purple Sandpiper

In Namibia, the Welwitschia orchid blooms for about eight weeks from January to March. Both male and female cones emit a resinous aroma when it is hot, and produce droplets as a reward for pollination in a daily rhythm. At least eight species of flies are pollinators, and perhaps bees and ants also join in. Although pollen can be blown away by the wind, the Welwitschia orchid is basically dependent on insects to pass on its genes, and perhaps their ancestors began to co-evolve with insects in the Triassic period.

The Ancient God Who Follows the Trend

Dinosaurs rose and died next to the Welwitschia plant, and now passing oryxes, rhinos and zebras will occasionally come to take a bite or two, chewing the ancient taste. The leaves contain the most compact chloroplast genome of land plants known to humans. The photosynthesis efficiency of the Welwitschia plant is very low, and it looks like an "old car", but in fact the DNA sequence in the chloroplast is evolving rapidly and remains simple under the pressure of natural selection.

Recently, the research teams of Xianhu Botanical Garden and Wuhan Botanical Garden and international partners discovered that the nuclear genome of Welwitschia, through DNA methylation (adding a large number of modifications to the DNA molecule to keep it intact but unable to work, equivalent to sealing the gene), maintains the smallest possible energy consumption and constantly active meristem without changing the genetic information, thus achieving ultra-long standby time (in all senses) in the desert.

Botanical illustration of Welwitschia. The anatomy is not typical of gymnosperms, but it is certainly not a true angiosperm. | Walter Hood Fitch / Curtis's Botanical Magazine (1863)

In today's climate, angiosperms have forced most gymnosperms to high and cold and barren lands. But the ancient Gnetales, as if they had tried all possible old rulers, are still participating in the disputes of the new world. Evolution has never had any fixed direction or distinction between high and low. The Welwitschia orchids that stick to the desert are calm but undercurrents are surging. They are both witnesses of history and another possibility for the future.

This article comes from the Species Calendar, welcome to forward

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