25-3 Plant Adaptations Davis Blass Ralph Beishline Tom Yeager

Brain Teaser Think about all the plants you have seen in your lifetime. Consider the environment where they thrive. How are certain plants adapted to a dry, desert- like environment? An aquatic environment? An environment with very few nutrients in the soil? What other adaptation may plants have?

I. Aquatic Plants A. Aquatic plants are able to tolerate mud that is saturated with water and nearly devoid of oxygen B. To take in sufficient oxygen, many aquatic plants have tissues with large air-filled spaces through which oxygen can diffuse

C. The reproductive adaptations of aquatic plants include seeds that float in water and delay germination for long periods D. Many aquatic plants grow quickly after germination, extending the growing shoot above the water's surface

II. Salt-Tolerant Plants A. When plant roots take in dissolved minerals, a difference in the concentration of water molecules is created between the root cells and the surrounding soil B. Concentration difference causes water to enter the root cells by osmosis

C. Roots of salt-tolerant plants are adapted to salt concentrations that would quickly destroy the root hairs on most plants D. The leaves of these plants have specialized cells that pump salt out of the plant tissues and onto the leaf surfaces

III. Desert Plants A. Plants that live in a desert biome are called xerophytes. In this biome they need to be able to tolerate conditions like strong winds, daytime heat, sandy soil, and infrequent rain. B. Plant adaptations to combat these conditions include extensive root systems, reduced leaves, and thick stems for water storage. Ex. Cacti C. Roots- stretch a long distance just beneath the soil or are extremely deep reaching. Also have many root hairs to quickly absorb water

D. Leaves- “spines” smaller surface area to reduce transpiration E. Stems- photosynthetic, store water. Swell during rainy periods, and shrivel during dry spells F. Seeds- can remain dormant for years until sufficient moisture guarantees a chance at survival. Plants can mature, flower, and set seed in weeks or even days, before the water disappears.

IV. Nutritional Specialists A. Grow in environments with low concentrations of nutrients. Include carnivorous plants and parasites B. Carnivorous Plants 1.Soil has little or no nitrogen present because no bacteria can survive to decay dead organisms. 2.Some plants have adaptations to trap and digest insects. Examples: Pitcher Plant- drown prey in pitcher-shaped leaves that hold rain water and digestive enzymes Sundews-leaf hairs tipped with sticky secretions Venus Fly Trap- hinged leaf blades. Trap prey when folded.

C. Parasites 1. Extract water and nutrients directly from host plant. They harm their host and may pose a threat to other organisms Examples: Cuscuta- no chlorophyll to make food. Grow directly into host’s vascular tissue. Mistletoe- parasite of conifers in Western U.S.

V. Epiphytes A.Plants not rooted in soil but grow on bodies of other plants, not parasites because they get their own water and make own food, live mainly in rainforests but also in other moist biomes Examples: Spanish moss and most orchids

VI. Chemical Defenses A.Many plants defend themselves against insect attack by manufacturing compounds that have powerful effects on animals Example: Foxgloves Effects: can be lethal if eaten, disrupt normal growth and development, prevent insects from reproducing Human Uses: aspirin, codeine, and other medicines Tobacco: chemical in tobacco is called nicotine, affects human nervous system, used to protect plant from predators Evolution: some insects have evolved to deal with poisons, monarch caterpillar can eat milkweed because it can store the toxic compounds in its body, makes it poisonous to other animals