What is a plant?

Plants are photosynthetic organisms with cell walls primarily made of cellulose. Historically, the term ‘plant’ referred to all living things that were not animals, including algae and fungi. However, modern definitions exclude fungi, some algae, and prokaryotes (archaea and bacteria).

Plants include flowering plants, conifers, gymnosperms, ferns, hornworts, liverworts, mosses, and green algae, but not red or brown algae. Most plants are multicellular.

Green plants derive energy from sunlight through photosynthesis in chloroplasts, which originated from symbiosis with cyanobacteria. These chloroplasts contain chlorophylls a and b, giving plants their green colour by reflecting green light, while absorbing blue and red light for growth.

Some plants, like parasitic or mycotrophic species, have lost the ability to photosynthesize, though they still produce flowers, fruits, and seeds.

Plants reproduce sexually and through alternation of generations, though asexual reproduction (cloning) also occurs.

There are approximately 391,000 plant species, with around 260,000–290,000 producing fruits and seeds.

Plants are vital for producing much of the world's oxygen and form the foundation of most ecosystems. Those that produce grains, fruits, and vegetables are key to human diets and have been cultivated for thousands of years. Plants are also widely used as decorations, building materials, writing materials, medicines, and psychoactive substances.

Fun and interesting facts about plants