Introduction to Plants

I. Plant Classification A. What criteria is used to classify plants? 1. The presence or absence of vascular tissue.

I. Plants Classification Cont. B. What is vascular tissue? 1. Xylem – tubular cells that transport water and dissolved minerals from the roots upward to the leaves 2. Phloem – tubular cells that transport sugars made in the leaves (photosynthesis) to other parts of the plant

II. Two Main Groups of Plants A. Non-vascular plants (Bryophytes) 1. since they have no xylem or phloem, water and minerals must travel in and out of the plant via osmosis and diffusion 2. Bryophytes are small plants like mosses and liverworts

II. Two Main Groups of Plants Cont. B. Vascular Plants (2 types) Plants that produce spores ex. Ferns, horsetails Plants the produce seeds a. Gymnosperms – seed plants that don’t produce flowers i. these vascular plants produce seeds called “cones” (Conifers) ii. ex. Evergreen plants (pine, spruce)

II. Two Main Groups of Plants Cont. b. Angiosperms – seed plants that produce flowers i. Develops seeds that are enclosed in fruits ii. Angiosperms may be monocots (grasses, lilies) or dicots (garden flowers, trees)

Gymnosperms Angiosperms NO FLOWERS FLOWERS Seed producing Spore producing SEEDS SPORES Bryophytes Vascular Plants Vascular Tissue Present NO YES PLANTS

Roots and Stems

I. Roots Roots are the underground parts of plants Root Functions 1. absorption – absorb water and minerals from the soil 2. Food storage – some plants (carrots) store food in their roots 3. anchorage – roots anchor plants to the ground

I. Roots Cont. C. Root Structure 1. Epidermis – the outermost cell layer of the root 2. Root hair – a. extension of an epidermal cell b. increases surface area to help absorb water and minerals

I. Roots Cont. 3. Cortex a. transports water and ions to the vascular core (made of vascular tissue) in the center of the root. b. parenchyma – cells which make up the cortex. Can act as storage for food or water. 4. Endodermis a. single layer of cells b. forms water-proof seal which surrounds roots’ vascular tissue. c. controls flow of water and dissolved minerals into the root

I. Roots Cont. 5. Pericycle a. just inside the endodermis b. can give rise to lateral roots 6. Xylem, Phloem, Cambium xylem and phloem are located at the roots’ center the cambium is located between the xylem and phloem the cambium is growth tissue that produces additional xylem and phloem cells

I. Roots Cont.

I. Roots Cont.

I. Roots Cont. D. Root Growth 1. Apical meristem – a. cells that are capable of growth b. located just behind the root tip 2. root cap – tough, protective layer of cells covering the root tip

II. Stems Stems are above ground portions of the plant Types 1. herbaceous stems – green, flexible 2. woody stems – hard, rigid

II. Stems Cont. C. Functions 1. support leaves and flowers 2. conduction of materials through xylem/phloem 3. growth 4. storage D. Internal structure 1. monocots – xylem and phloem scattered throughout the stem

II. Stems Cont. 2. dicots – xylem and phloem arranged in vascular bundles which form a ring between the cortex and the pith (central tissue) E. Stem Growth 1. Primary growth – elongation, growth in height 2. Secondary growth – growth in width F. Tubers 1. enlarged, underground stems that act as storage organs (ex. potatoes)

II. Stems Cont. Monocot Stem Dicot Stem

III. Root Diagrams Diagram 1 1. Epidermis 2. Root Hairs 3. Apical Meristem 4. Root Cap Diagram 2 5. Root hairs 6. Cortex 7. Endodermis 8. Phloem 9. Xylem