Tree Tumbo

Welwitschia mirabilis

Taxonomy

Eukarya plantae pteridophyta equisetopsida gnetales welwitschiaceae Welwitschia mirabilis, or better known as Tree Tumbo (Welwitschia mirabilis). It's genus was named after it's discoverer Friedrich Welwitsch. It's species is translated from Latin to English as "wonderful" or "extraordinary."

Adaptation

-The Tree Tumbo is documented as one of the world's ugliest plants. It has a very long taproot to reach underground water supplies. Two very long and leathery leaves extend horizontally from a stem base. In it's lifetime, the plant only has the two leaves, which never get shed and just continually grow. It's leaves droop down towards the ground. This is because during fog, water condenses on the leaves, and runs down to the ground, near the roots. Through many years of wear, the leaves get worn and tattered towards the ends. The typical height for this plant is one meter, but it can grow up to two meters in height. After a seed has been planted, it matures at about 9 months, but it takes about two and a half years for it to flower for the first time. It is a gymnosperm which means it disperses seeds using cones. It also has corky bark which helps resist fires. Unlike many plants, a Tree Tumbo plant is either male or female, not both.

-This plant requires an extremely specific habitat. It lives in an arid and semi-arid desert. In order to survive, it doesn't grow in areas with much rain, but one that receives consistent amounts of fog. The only place where it has been found to grow is in small, isolated regions in the Namib Desert, which spreads across Northern Namibia and southern Angola.

- Because it is a plant, it does not have normal social or food behaviors. It does interact with other animals however. It provides some food to antelope and rhinos in dry seasons. This doesn't damage the plant however, because only the leaves are consumed and they will regrow. The core of the plant was consumed by some early African cultures. It's leaves also provide some shelter to small insects, arachnids, and mammals.

Reproduction

Discovery

Friedrich Welwitsch

The Tree Tumbo was discovered in 1859 by Friedrich Welwitsch, a botanist from Austria. Welwitsch was sent to Angola by the Portuguese government to study the local plant life. He found many new species, including the Tree Tumbo, and he collected samples and sent them back to Europe.

Evidence of Evolution

Mutation of the trnR-CCG

In the Tree Tumbo, one of the most notable mutations is the complete duplication of the trnR-CCG gene. These gene is a plastid gene, meaning it exists in the DNA in the plant's chloroplast. The gene serves at tRNA, and it carries the amino acid arginine. Arginine provides storage for nitrogen in plants. Nitrogen is an essential element for the growth of plants, and it is used in essentially all fertilizers. The additional gene could help in the storage of nitrogen and the growth of the plant in an ecosystem where nutrients are limited. This mutation was most likely random, by the method of duplication, which in this case duplicated an entire gene. It spread throughout the entire species as demonstrated below. The plants with the mutation could grow larger and disperse more seeds, meaning over time it would out-compete the plants lacking the mutation. Since the gene is on chloroplast DNA, it is only transmitted by the female plant, and it will also be transmitted to every one of that plant's offspring.
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Gymnosperms were believed to dominated the flora of the Jurassic Period. Plants like the Tree Tumbo are believed to have stayed relatively the same since that period. The most major difference that have occurred in the past is the plants would shrink because of increased competition with other types of plants. The picture above demonstrates how the female spreads the gene to all of it's offspring. It also shows how plants with the extra gene can have more offspring, because of increased growth. Overtime, every plant of that species would have the mutation.

Atlin Johnson

Mr. Parson's 1st Period Biology