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Plants are altruistic–Sharing more food with siblings Plants are altruistic–Sharing more food with siblings Do plants perform best with family or strangers? The findings of the new study suggest that plants, like humans and animals, have the ability to be altruistic. By studying the fertilized seeds of corn, scientists from the University of Colarado, have discovered a form of plant altruism. A corn seed contains an embryo and corresponding bit of tissue called endosperm, which feeds the embryo as the seed grows. The study found fertilized seeds sharing the same mother and father were heavier than those with an embryo and endosperm from genetically different parents. This suggests an endosperm is more likely to cooperate and share more food with a genetically related embryo. In this chapter, we will explore the reproductive biology of plants in much greater detail.

Learning Objectives

After completing the topic, the student will be able to:

  • Define “vegetative propagation” of plants and list different methods of vegetative propagation for obtaining desired characteristics in horticulture and in agriculture.
  • Define and discuss the term “tissue culture” and appreciate the importance of this phenomenon.
  • Identify the reproductive organs of flower and Explore how sexual reproduction occurs in plants.
  • Analyze how male and female gametes are formed in a flower.
  • Define and distinguish self–pollination and cross pollination and list different types of cross pollination methods.
  • Investigate the difference between pollination and fertilization in flowering plants.
  • Systematize the main stages of germination of a seed and understand the types of germination methods.
  • Define and discuss the terms Apomixis and Polyembryony and appreciate the significance of apomixis.
Tulip flower Tulip flower (Tulipa ′Queen of the Night′). Close up of the flower′s reproductive structures Flowering plants are the dominant plant form on land and they reproduce by sexual and asexual means. Often their most distinguishing feature is their reproductive organs, commonly called flowers.
Plant Reproduction

Reproduction is the biological process by which new individual organisms are produced. Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction. The known methods of reproduction are broadly grouped into two main types: sexual and asexual.

Plants create more of their own kind by either sexual reproduction or asexual reproduction. In sexual reproduction, a male sperm cell joins with a female egg cell to produce a new plant. Both the egg and the sperm cells contain genes (hereditary material). Genes determine many of the characteristics of a plant. A plant that is produced by sexual reproduction inherits genes from both parent plants. It is a unique individual and has traits that may be different from either parent.

Sexual reproduction in flowering plants involves the production of male and female gametes, the transfer of the male gametes to the female ovules in a process called pollination. After pollination occurs, fertilization happens and the ovules grow into seeds within a fruit. After the seeds are ready for dispersal, the fruit ripens and by various means the seeds are freed from the fruit and after varying amounts of time and under specific conditions the seeds germinate and grow into the next generation.

Asexual reproduction can occur in many ways. It often involves the division of one plant into one or more parts that become new plants. These plants inherit genes from only one parent and have exactly the same characteristics as the parent plant. This type of asexual reproduction is called vegetative propagation. Many plants reproduce both sexually and by vegetative propagation.

Insects attracted Insects attracted to the showy flowers carried out pollination Some insect groups, such as bees, originated after flowering plants, their members developing mouthpart structures and behavior specialized for pollination.
Evolutionary significance of plant reproduction

The incredibly attractive, colorful, and unique features of the most abundant and diverse group of plants—the flowering (angiosperms)—are believed to have evolved primarily to maximize the efficiency and speed of outcross reproduction. Each major burst of angiosperm evolution was a co- evolutionary episode with associated animals, primarily insects, which were exploited to disperse pollen and seeds in ever more efficient and diverse ways.

The major fragment of angiosperm evolution was the appearance of the closed carpel together with showy flowers that were radially symmetrical . The closed carpel prevented self-fertilization through recognition and blocking of self pollen within the specialized conducting tissue of the style. Insects attracted to the showy flowers carried pollen between plants less wastefully than wind, and the radial symmetry accommodated insects of many sizes and shapes, thus succeeding pollination.