Relict plants. Kinds of relic plants

Relics are organisms that have been preserved on Earth in certain territories since antiquity, despite the changing conditions of existence. They are the remnants of ancestral groups, widespread in the past geological epochs. The word "relic" comes from the Latin reliquus, which in translation means "left over."

Relict plants and animals are of great scientific value. They are carriers of information and can tell a lot about the natural environment of past eras. Let's get acquainted with plant organisms, referred to the relic.

Geographic relict plants

Geographic relict plants include species preserved in a certain region as a remnant of past geological epochs, in which conditions of existence differed significantly from modern ones. For example, neogenous (tertiary) relics include tree-forming tree species (chestnut, zelkova and some others), a number of evergreen shrubs (Kolkhida wormwood, boxwood, prickly pear, Rhododendron Pontic, etc.), as well as herbaceous plants growing in Colchis. These are enough heat-loving species of relic plants, so they were preserved in places with a warm climate.

Examples of glacial relics are the bog saber, which grows in the Caucasus, and the dwarf birch preserved in central Europe.

Phylogenetic relicts (living fossils)

These presently existing species belong to large taxa, almost completely extinct millions of years ago. They are preserved, as a rule, due to the isolation of their habitat from more progressive groups. Phylogenetic include such relic plants as ginkgo, metasequoia, horsetail, csididopitis, wollemia, liquidambar, velvichia.

Ginkgo

Relic tree, which is one of the oldest on Earth. Studies of fossil samples show that the age of ginkgoids is at least 200 million years. They appeared at the beginning of the late Permian, and in the middle of the Jurassic there were already at least 15 genera of Ginkgo.

Ginkgo biloba is the only species preserved to date. This is a deciduous plant related to gymnosperms. Its height reaches 40 meters. Trees are characterized by a well-developed root system, resistant to unfavorable weather conditions, in particular to strong winds. There are specimens that have reached the age of 2,5 thousand years.

Since in addition to ginkgo, pine and spruce belong to the gymnosperms, the plant we considered earlier was also referred to as coniferous, although it is very different from them. However, to date, there are suggestions that the ancestors of Ginkgo are the ancient seed ferns.

Earlier you could see these so-called living fossils only in China and Japan. But today the plant is cultivated in parks and botanical gardens in North America and the subtropical zone of Europe.

Metasequoia

Refers to the genus of coniferous trees of the Cypress family. Currently exists in the only preserved relict form - Metasequoia glyptostroboid (Metasequoia glyptostroboides). The plants of this species were widely spread in the forests in the Northern Hemisphere. Dying began because of a change in climatic conditions and competition with broad-leaved species. Live specimens of this tree were discovered in 1943. Before metasequoia was met only in the form of fossils and was considered extinct.

To date, these relict plants in the wild have survived only in the provinces of Sichuan and Hubei (Central China) and are listed in the International Red Book, as they are on the verge of extinction.

Due to the external attractiveness metasequoia is grown in the gardens and parks of Central Asia, Ukraine, Crimea, the Caucasus, as well as in Canada, the USA and in several European countries.

Liquidambar

Liquidambar (Liquidambar) belongs to the genus of flowering plants of the family Aptingieva, which includes five species. These relict plants were widely spread in the Tertiary period. The cause of their extinction on the territory of Europe was a massive icing during the glacial period. Climate change also contributed to the disappearance of the species from the territories of North America and the Far East.

Today, liquidobambs are widespread in North America, Europe and Asia.

They are quite large deciduous trees, growing to 25-40 meters, with palm-lobed leaves and small flowers collected in a spherical inflorescence. The fruit has the appearance of a wooden box, inside which there are many seeds.

Horsetail

These relicts are plants of the genus vascular, preserved in large numbers and numbering about 30 species today. All the varieties that grow now are perennial herbs. The height can grow up to several meters. The largest species is the Giant Horsetail (Equisetum giganteum). With a trunk diameter not exceeding 0.03 m, its maximum height can reach 12 meters. Giant horsetail grows in Chile, Mexico, Peru and Cuba. There also grows the most powerful species - the horsetail of Schaffner (Equisetum schaffneri). At a height of 2 meters, its diameter reaches 10 cm.

Stems of horsetails are characterized by high rigidity, which is due to the presence of silica in them. Also, plants have highly developed rhizomes with subordinate roots in the nodes, due to which they are very resistant to various unfavorable factors and can survive even a forest fire. Horsetails are widespread on most continents, except for Australia and Antarctica.

Wollemia

Coniferous relict tree, represented by a single species - Wollemia noble (Wollémia nóbilis). It is one of the oldest plants. It grew back in the Jurassic period. The plant was considered extinct for a long time. However, in 1994, wollemy was discovered by one of the employees of the National Park of Australia, David Noble, in honor of which the species (nobilis - "noble") was named. Almost a whole relic grove was found. The age of the oldest of the discovered trees is supposedly more than 1000 years.

Wollemia is a rather tall tree. So, it can reach 35-40 meters. The foliage of the plant is completely identical to the leaves of Agathis Jurassic, which grew about 150 million years ago and is the alleged fossil ancestor of wollemia from the late Jurassic period.

Сциадопитис

There is a unique form - Sciadopitys verticillata (Sciadopitys verticillata). In the past geological epochs, this kind of tree was very widespread. This is evidenced by the fact that their remains were found in Cretaceous sediments in Japan, Greenland, Norway, Yakutia, the Urals.

At present, in the natural environment, cispidoptis grows only on some islands in Japan, where it was preserved at an altitude of 500-1000 m above sea level in moist mountain forests, as well as on slopes, in deaf gorges, in groves.

Sciadopitis is an evergreen tree with a pyramidal crown. It can grow to a height of 40 m. The trunk size in the girth is up to 4 meters. Characterized by very slow growth. The tree is often called the "umbrella pine" because of the unique structure of the needles. Its flattened needles, having an average length of up to 0.15 m, form false whorls and are spread apart, like spokes at the umbrella.

The fruits of sciadopitis are cones of oval form, the maturation period of which is two years.

Since csidopitis can for a long time grow in containers, it is often used in ornamental horticulture as a room and greenhouse plant. As a park culture introduced in Europe since the 19th century.

Velvicia

Velvichia is an amazing (Welwítschia mirábilis) - the only species preserved to this day. One of the three representatives of the former was a fairly numerous class of oppressive, which are still encountered today. Its name Velvichiya surprising received thanks to an unusual appearance.

The plant does not look like grass, bush, or tree. It is a thick trunk, 15-50 centimeters protruding above the surface of the soil. The rest of it is hidden under the ground. And while the leaves of the relic reach 2 m in width and 6 m in length. The age of some specimens is more than 2000 years.

The place of welwichie growth is the southwestern part of Africa, namely the stony Namib Desert, located along the Atlantic coast. The plant is very rare to be found further than 100 m from the shore. This is explained by the fact that this distance can be overcome by fogs, which are the source of life-giving moisture for the wielvichi.