How can plants reproduce

Sometimes there are separate female and male flowers, but they are on the same plant. Monoecious plants are examples of selfers because they do not need two separate plants in order to reproduce.

How many of the selfers pictured in Figure 2 do you know? Cross-fertilizing plants, known as outcrossers , need two separate plants in order to reproduce. Sometimes, a flower can have both pollen and ovules, but they cannot fertilize each other; this is called self-incompatibility. For outcrossers to successfully reproduce, the pollen and ovules need to be from separate plants.

In other cases, the two sexes are completely separate, with some plants making only male flowers and other plants making only female flowers.

This is similar to how reproduction works in most animals. The pollen from the male plants needs to travel to the ovules of the female plant in order to produce seeds. How many of the outcrossers pictured in Figure 2 do you know? There are still a lot of mysteries about how and why some types of outcrossers are dioecious. Scientists decided to look at the DNA from many different kinds of dioecious plants to try to understand what makes them male or female.

There is a lot you can learn from DNA that may not be so obvious from just looking at or growing a plant. A DNA sequence is a lot like letters on a keyboard: the letters by themselves do not mean anything, but when they are put together they can form words.

Scientists compared the genes from several dioecious plants to figure out which genes were important in determining whether a plant is male or female. They discovered that there are several ways a plant can determine gender.

For example, there can be genes in the DNA that make plants male or genes that prevent them from becoming female [ 1 ]. Looking at plant DNA is not the only way scientists can learn about the differences between male and female plants.

For example, they can study the shape differences between male flowers and female flowers. You can do this too! Unlike humans, plants cannot move around. This means that plants need to use other strategies to move pollen to ovules to make seeds.

For outcrossers, the male plants do not need to spend their energy making seeds, so they can spend more energy on making and dispersing high-quality pollen. Similarly, since female plants do not need to make pollen, they can spend more energy on making high-quality ovules. This means that they can pass on more resources to their offspring to improve their chances of survival.

Furthermore, because dioecious plants need two different plants to reproduce, the offspring will have more variety in the genes they get from the parents. The plant part often gives rise to an undifferentiated mass, known as a callus, from which, after a period of time, individual plantlets begin to grow. These can be separated; they are first grown under greenhouse conditions before they are moved to field conditions.

The life cycles and life spans of plants vary and are affected by environmental and genetic factors. The length of time from the beginning of development to the death of a plant is called its life span. The life cycle, on the other hand, is the sequence of stages a plant goes through from seed germination to seed production of the mature plant.

Some plants, such as annuals, only need a few weeks to grow, produce seeds, and die. Other plants, such as the bristlecone pine, live for thousands of years. Some bristlecone pines have a documented age of 4, years. Even as some parts of a plant, such as regions containing meristematic tissue the area of active plant growth consisting of undifferentiated cells capable of cell division continue to grow, some parts undergo programmed cell death apoptosis.

The cork found on stems and the water-conducting tissue of the xylem, for example, are composed of dead cells. Plant life spans : The bristlecone pine, shown here in the Ancient Bristlecone Pine Forest in the White Mountains of eastern California, has been known to live for 4, years. Plant species that complete their life cycle in one season are known as annuals, an example of which is Arabidopsis , or mouse-ear cress. Biennials, such as carrots, complete their life cycle in two seasons.

Commercial growers harvest the carrot roots after the first year of growth and do not allow the plants to flower. Perennials, such as the magnolia, complete their life cycle in two years or more.

In another classification based on flowering frequency, monocarpic plants flower only once in their lifetime; examples of monocarpic plants include bamboo and yucca. During the vegetative period of their life cycle which may be as long as years in some bamboo species , these plants may reproduce asexually, accumulating a great deal of food material that will be required during their once-in-a-lifetime flowering and setting of seed after fertilization.

Soon after flowering, these plants die. Polycarpic plants form flowers many times during their lifetime. Fruit trees, such as apple and orange trees, are polycarpic; they flower every year. Other polycarpic species, such as perennials, flower several times during their life span, but not each year.

By this method, the plant does not require all its nutrients to be channeled towards flowering each year. As is the case with all living organisms, genetics and environmental conditions have a role to play in determining how long a plant will live.

Susceptibility to disease, changing environmental conditions, drought, cold, and competition for nutrients are some of the factors that determine the survival of a plant. Plants continue to grow, despite the presence of dead tissue, such as cork. Individual parts of plants, such as flowers and leaves, have different rates of survival. In many trees, the older leaves turn yellow and eventually fall from the tree.

Leaf fall is triggered by factors such as a decrease in photosynthetic efficiency due to shading by upper leaves or oxidative damage incurred as a result of photosynthetic reactions. The components of the part to be shed are recycled by the plant for use in other processes, such as development of seed and storage.

This process is known as nutrient recycling. However, the complex pathways of nutrient recycling within a plant are not well understood. The aging of a plant and all the associated processes is known as senescence, which is marked by several complex biochemical changes.

One of the characteristics of senescence is the breakdown of chloroplasts, which is characterized by the yellowing of leaves. The chloroplasts contain components of photosynthetic machinery, such as membranes and proteins. Chloroplasts also contain DNA. The proteins, lipids, and nucleic acids are broken down by specific enzymes into smaller molecules and salvaged by the plant to support the growth of other plant tissues. Hormones are known to play a role in senescence. Applications of cytokinins and ethylene delay or prevent senescence; in contrast, abscissic acid causes premature onset of senescence.

Plant senescence : The autumn color of these Oregon Grape leaves is an example of programmed plant senescence. Privacy Policy. Skip to main content. Plant Reproduction. Search for:. New Zealand has about species of ferns and over species of moss. Classification helps us put order into the world around us. Scientists start with very big categories like plants and animals and continue to divide the groups based on shared characteristics — like methods of reproduction.

Take a bag of thawed frozen broad beans to school and hand a few to each student. Students can remove the seed coat and split the bean to reveal the embryo inside. Use magnifying glasses to examine the embryos.

Add to collection. Nature of science Classification helps us put order into the world around us. Activity idea Take a bag of thawed frozen broad beans to school and hand a few to each student. Go to full glossary Add 0 items to collection.

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