Chapter 20-Fungi and Plants Section 1- Fungi Section 2 – Early Land Plants Section 3 – Seed Plants

Section 1-Fungi Characteristics of Fungi All Fungi are heterotrophs– fungi are not green so they don’t contain chlorophyll or make food from sunlight. They get their food from their surroundings. The bodies of multicellular fungi are made of filaments. These filaments are long strings of individual cells called hyphae. Each cell is separated by a wall with holes called a septa. The holes allow the cytoplasm and nuclei to flow from cell to cell. As the hyphae grow, they branch and form a tangle mass called a mycelium.

Cell walls of fungi contain chitin Cell walls of fungi contain chitin. This is the same material found in the exoskeleton of insects and other arthropods. Chitin is more resistant to decomposition by bacteria than is the cellulose of plants. Fungi digest food outside their bodies. Fungi get food from both living and dead animals and plants. As the hyphae spread through a food source, they secrete enzymes that break down organic matter. The hyphae then absorb the nutrients. The mycelium of a fungus may have many meters of hyphae.

Most fungi reproduce by spores Most fungi reproduce by spores. The only parts of a fungus you can see are its reproductive structures. Most of the hyphae are woven inside the food source. Mold or mildew produce clusters or short strings of tiny, beadlike spheres on the tips of hyphae. These tiny structures are reproductive cells called spores. A fungal spore can develop into a new individual. Spores can withstand dry conditions and a wide range of temperatures. Some can be carried by air currents. Some are sticky and cling to animals for transport. If a spore lands on a food source with enough moisture, the spore rapidly grows a hypha.

Section 2- Early Land Plants Characteristics of plants Photosynthetic Cell walls made of polysaccharide called cellulose Many types of cells arranged in tissues Most plants have vascular tissues To grow large, must have internal tubes called vascular tissue that transport water and nutrients Vascular plants are roses, houseplants, grasses, oak trees and ferns

Nonvascular plants – do not have vascular tissue so must transport water and nutrients by osmosis and diffusion. Must live in wet environments They need a film of water to reproduce so sperm can swim to egg They are relatively small – most are less than 1 in tall Most are anchored by a root-like structure called a rhizoid. The leaf-like structure are only one or two cells thick Water enters through pores on the undersurface where it is not covered by cuticle. Mosses are the most widespread nonvascular plants. They can grow in dense carpets on the forest floor. The gametophyte is the dominant form of the nonvascular plants

Section 3 – Seed Plants The most important feature of plants with seeds is that plants could now exist in dry environments. Seed plants have woody tissues which allow plants to grow tall and compete for sunlight.l Seed plants have a more complex vascular tissue that lets water and nutrients be carried to the new heights. Seed plants also no longer need water to reproduce – the use pollen, cones, or flowers and seeds.

Seeds are able to survive unfavorable conditions Seeds are able to survive unfavorable conditions. Each seed contains an embryo, baby plant, and stored nutrients the embryo uses as it begins to grow. The structure of the seed that stores the nutrients is called the cotyledons. The seeds are either a monocotyledon (one seed leaf) or a dicotyledon (two seed leaves). The hard outer seed coat covers the embryo protecting it from physical injury or drought. A seed can lie dormant for years and still grow into a healthy plant.

Special features on seeds include hooks, feathery projections, or winglike projections. These are all characteristics that help to move seeds from place to place.

Gymnosperms: Plants with naked seeds The seeds do not develop within a fruit Most seeds form in a cone, which are clusters of scales or modified leaves The most familiar gymnosperms are firs, pines, junipers, redwoods, and spruces