Plants – Characteristics and Function

Evolution of Plants Scientists believe that terrestrial plants evolved from green algae as both show the following similarities: Use starch as their primary food reserve Have cellulose in their cell walls Use chlorophyll a and b for photosynthesis

Evolution of Plants In order to adapt to the drier, terrestrial environment, plants developed specialized structures to avoid water loss (bark), obtain nutrients (roots, stems, leaves) and reproduce/grow (spores, seeds, flowers)

Evolution of Plants The first plants were non- vascular, like moss, that depended on osmosis and diffusion to get water and nutrients. Vascular plants evolved which had specialized cells used for the transport of water (Xylem) and nutrients (Phloem), called vascular tissue.

Plant Tissue Like animals, plants are made up of four types of tissue: 1.Meristematic tissue is where cell growth occurs. 2.Dermal tissue is the outermost cell layer of the plant. It is used for protection and to prevent water loss.

Plant Tissue 3. Ground tissue is the inner cell layers of the plant that is not vascular tissue. This is where nutrients are stored and where the plant does photosynthesis. 4. Vascular tissue are the cells involved in transporting water and nutrients through the plant.

Main types of vascular plants Gymnosperms: mainly coniferous trees, seeds appear on cones, make up the majority of Canadian forests, termed ‘softwood’ by lumber companies and provide most of the money earned by Canada’s forestry industry.

Main Types of Vascular Plants Angiosperms: many more species than gymnosperms, live in a wider variety of habitats, use flowers to reproduce and encase the seed in a ‘fruit’, divided into monocots and dicots.

Monocots and Dicots CriterionMonocotsDicots Seed Leaves12 Veins in Leaves ParallelNetlike Vascular Bundles in Stems ScatteredArranged in a ring Flower PartsPetals are multiples of 3 Petals are multiples of 4 or 5

Monocots Only about 10% have a woody stem (bamboo and palm trees). Most have a herbaceous stem which is soft and fleshy (grass, tulips, etc…) Rice, corn, wheat, onions, carrots, …

Dicots Deciduous trees are dicots. Termed ‘hardwood’ and make up a good portion of the lumber industry in Canada. Other dicots: beans, potatoes, most wildflowers and salad ingredients (tomatoes, lettuce, cabbage, radishes…)