This edition: Plant Structure
For most people, few days pass without a significant encounter with plants. They stimulate our senses and sustain our bodies in a relationship that dates to the origins of humankind. Many plants also share a trait: flowers. Most of the 300,000-plus known species on Earth are flowering varieties called angiosperms. Dr. Ann Hirsch studies the roots of plants, which have the crucial job of collecting nutrients for plant growth and maintenance, and for processing nitrogen.
Looking deeper into plant tissues, the program indicates that primary growth originates at apical meristems and at meristematic tissues derived from them. Secondary growth includes the thickening of the stems and roots. Dr. Arthur Gibson tells us about the variety of stems, from grass to lumber, and explains why the differing meristem cells are necessary.
An animation illustrates the cohesion-tension theory of water transport. As water molecules exit the plant via transpiration, cohesion of water creates tension throughout the plant to pull water molecules into the roots and xylem. This type of movement and other crucial processes rely on the leaves, which are the organs for photosynthesis and balancing the outside environment and internal workings of the plant or tree. Dr. Robert Heath guides us through leaf structure and function.