The world of plants
Plants grow attached to the soil; green plants photosynthesise, making glucose from carbon dioxide and water and releasing oxygen, and like all living things they also breathe (taking in oxygen and releasing carbon dioxide). The body has vegetative and generative organs. Vegetative organs – root, stem, leaf – provide nutrition, growth and development. Generative organs – flower, fruit, seed – provide reproduction and spread. Organs are made of tissues (protective, ground, mechanical, conducting, formative, secretory). In nature plants release oxygen, act as producers that make organic matter, begin the food chain and humidify the air by evaporating water. People use them as food, medicine, fodder, raw materials (timber, cotton) and ornamental plants. The Swedish scientist Carl Linnaeus founded systematics. Plants are grouped by similarity: species → genus → family → class → division → plant world. For example, the common dandelion: division – flowering plants (angiosperms), class – dicotyledons, family – the daisy family, genus – dandelion, species – common dandelion. Maize belongs to the monocotyledons, in the grass family; its species name is maize.
“Taxonomy ladder” exercise: draw a six-step ladder in your notebook (species, genus, family, class, division, world) and place the dandelion’s classification on it from bottom to top. Then, using a book or the teacher’s help, place a plant that grows at home (such as wheat) on the ladder. Safety: when outdoors do not put unknown plants in your mouth or taste them.