What Are Tracheophytes?
There are basically two types of plant life that grow on land these being bryophytes and tracheophytes. Bryophytes have no root, leaves or stems. Mosses, hornworts and liverworts fall into this category. Tracheophytes have roots, stems and leaves. Trees, shrubs, grains, flowers, grasses etc. are considered tracheophytes.
Tracheophytes utilize a vascular system for absorption of food, water and metabolism. They have xylem tissue that transports water and food to tissue called phloem. A waxy layer called a cuticle helps to hold in the water. Tracheophytes also have stomata, or pores to take in gases like carbon dioxide and release gases like oxygen. In the process of photosynthesis, the leaves capture the energy of the sun to change water and carbon dioxide into a sugar called glucose. The glucose is then used for energy and to make cellulose and starch. Cellulose is used in building cell walls. The starch is stored in seeds and plant parts as a food source. This is why seeds like rice and grains are filled with starch.
There are nine divisions or phyla of tracheophytes, divided into three major groups according to their reproduction method:
Psilopsid or seedless
Gymnosperm or non-flowering
Angiosperm or flowering
The psilopsid group reproduces by spores. Plants such as ferns have spores on the underside of their fronds. This is called the sporophyte stage. The spores release and fall to the ground and become prothallus, the gametophyte stage. The prothallus then produces both sperm and egg cell. Once the egg is fertilized it becomes a new fern and the cycle begins again.
The gymnosperm group which means naked seed, consists of plants that produce a cone, such as pines, firs, cedars and redwoods. In this group the plant usually produces both a female or seed cone and a male or pollen cone. The seeds develop in the exposed upper surface of the female cone and are fertilized by pollen that is released from the male cone and carried by the wind.
The angiosperm group is by far the largest of the three groups consisting of over 250,000 species of flowering plants ranging from small flowers to huge trees. The seeds are covered in a protective shell called a fruit. This group is divided into two categories, monocots and dicots, or one seed leaf or two seed leafs. The flower is the reproductive center of the angiosperm, containing both the male and female parts. The male reproductive structure is called a stamen and is usually a slender threadlike filament topped with anthers filled with pollen. The female reproductive structure is called a pistil and contains a stigma, style and ovary. The pollination usually occurs through the wind, insect, or other animals. The male pollen travels down the style to the female ovary where it then fertilizes the egg. The egg then becomes a seed with an embryo. Under proper conditions this seed can then produce another plant.