Question

Why would plants need to evolve vascular tissue, lignin, and the different reproductive mechanisms (cone versus flower).

Answer 1

The vascular tissue includes xylem and phloem,these two help in transportation of nutrients and other fluids throught out the plant tissue. While lignin is an important supporting tissues for the plants,which seve its function by helping cellwall formation in plants.Reproduction is an important mechanism for the developement of next generation in plants. Plants reproduce sexually and asexually. In case of cone bearing plants,they have male and female cone in which male cone produce pollen (a sticky powder) . This pollen from male cone get transport by wind or other mediators to female cone. In case of flowering plants,they have different parts (male and female parts).Male part is called stamens that produce pollen and female part is pistil.This pistil's top have stigma which is sticky when pollen fall by means of insectors or animals and polllination occurs.Here self- pollination in which pollen is transfer between stamen and stima of same plant can occur.Also cross-pollination where the stamen and stigma of defferent plants are involed in pollination.But in cross-pollination the plants should be same species.