Algae are the oldest group of plants on the planet. One of the representatives of this systematic unit is ulotrix. Reproduction, habitat and vital processes of this plant are the subject of study in our article.
Department of Green Algae
This group of lower plants has about 15 thousand species. Among them are unicellular representatives. These are chlorella and chlamydomonas. Volvox is a colony of green algae that resembles a ball in shape. Its diameter is small - only 3 mm. In this case, one colony can count 50 thousand cells.
Ulotrix, the reproduction and structure of which we are considering, is a multicellular alga. A similar structure have ulva, spirogyra, cladophora, hara.
The structure and reproduction of ulotrix
Lower plants do not form tissues. The body of multicellular species is called the thallus, or thallus. The function of attachment to the substrate is performed by filamentous formations - rhizoids. Their cells are also not differentiated.
Tallot ulotriks has a filamentous unbranched shape. It consists of cells arranged in one row. These algae live in marine and fresh water bodies, attaching rhizoids to snags, stones and other underwater objects. Ulotrix threads grow to a length of 10 centimeters. Together they form green mud.
A mandatory component of each ulotrix cell is a parietal chloroplast with several pyrenoids. The latter represent an area in which organic substances synthesized during photosynthesis are deposited in reserve.
Ulotrix cells are eukaryotic. This means that their genetic material is contained in the formed nucleus. It is encoded in nucleic acid molecules - DNA. Such a structure of the genetic apparatus causes a variety of ways of reproduction of ulotrix.
Vegetative propagation
This method of propagation of ulotrix is characteristic of all plants. Its essence lies in the development of a new organism from the multicellular part of the mother. In the case of ulotrix, these are scraps of thread. This method of vegetative propagation is called fragmentation.
Ulotrix: reproduction by spores
Another method of asexual process is spore formation. During this process, only thallus cells can participate. Each of them is divided into several parts. They are called spores - asexual reproduction cells.
For ulotrix, this method is quite effective. This is due to the fact that absolutely every cell of the thread is capable of division. The number of spores that forms during this process varies widely - from 4 to 32. At first, they freely move in the water column, protected by the mucous capsule. During this period they are called zoospores. Each of them is equipped with four flagella, which allow them to move freely in the water column.
The significance of this phase of the life cycle is the resettlement of plants. Next, each spore should attach to a solid substrate. Only under this condition will it grow into a thread of ulotrix. First, the zoospore loses its flagella, its cell wall becomes denser and the cell proceeds to division.
Gamete development
The next stage in the life cycle of spirogyra is the sexual process. Each cell of the thread also forms a significant number of gametes - from 4 to 64. Sexual reproduction of ulotrix is isogamous. This characteristic means that germ cells of the same structure participate in it. They are not divided into male and female. Such gametes are identical in shape and size. They are indicated by a plus or minus sign.
With isogamy, germination of germ cells occurs by copulation, the result of which is a zygote. Each gamete forms two flagella, with the help of which it goes into the water. Fertilization takes place there. An interesting fact is that gametes formed on different threads are capable of merging. This phenomenon is called heterotallism.
In the life cycle of ulotrix, a generational change is observed. This phenomenon is adaptive in nature. When adverse conditions occur, filamentous algae cells become round. Their walls secrete a large amount of mucus. This state of cells is called palmeloid. Then they separate, their mitotic division occurs. When environmental conditions return to normal, newly formed cells turn into motile zoospores. Of these, filamentous thalli develop.
So, ulotrix is a representative of the group of lower plants, the department of Green algae. His body is a filamentous thallus, consisting of undifferentiated cells. Ulotriks lives in fresh, and sometimes in salty reservoirs. Leads an attached lifestyle. Attaches to underwater objects using filamentous rhizoids. Ulotrix reproduces in three ways: vegetatively, spore formation, and by fusion of motile gametes.