Chapter 28: Flowering Plants

Most of your notes for this Chapter will be found in your Flowering Plant Lab. However, here are some notes in addition to your lab. Angiosperms have dominated earth for 60 million years; 250,000 million species are known today. Monocots include orchids, palms, lilies, grains, grasses. Dicots include shrubs, trees (except for conifers), ornamental plants, many food crops. Know traits of each! (Lab) & See left. 3 Plant organs: roots, stems, leaves (Lee also lab) 1. Roots: Root hairs-increase surface area of root for absorption Large taproots - store food such as starch for plant (Ex: carrots, turnips, sugar beets, sweet potatoes.)

2. Stems - Terminal bud is at apex of stem when plant stem is growing in length. Axillary buds, in angle formed by a leaf and stem) are dormant. Terminal bud produces hormones inhibiting growth of axillary buds = apical dominance, so plant can grow up to sun. Axillary buds begin growing and develop into branches under certain conditions. What is “pinching back?” 3 kinds of Modified stems: Runner in a strawberry plant = horizontal stem - new plants emerge from tip of runner = asexual reproduction Rhizome of an iris plant =horizontal underground stems = store food, & can bud new plants Tubers are rhizomes ending in enlarged structures (potatoes). Eyes of potato are axillary buds, can grow when planted.

3. Leaves - flat blades (for light collection) and petioles (joins leaf to stem.) Celery is a big petiole. Tendrils = modified leaves for climbing and support. Spines of a cactus = modified leaf parts protecting plant. Cactus stem is photosynthetic. Plant Cells - have chlorophyll, large central vacuole, some have a multipart cell wall: Primary cell wall - laid down first Secondary cell wall - deposited between plasma membrane and primary wall, more rigid for support Parenchyma cells - most abundant cell, for food storage, photosynthesis. Only primary cell walls. Collenchyma cells - provide support in growing parts of plant. Only primary cell walls. Sclerenchyma cells - have thick secondary walls with lignin (wood). When mature, most are dead - rigid cells support plants. Make rope and clothing.

2 Plant Vascular Tissues: 1. Xylem - contains water conducting cells - move water & minerals up stem 2. Phloem -contains food conducting cells - transport sugars from leaves or storage tissue to other parts of plant 3 Tissue Systems continuous throughout plant: 1. Dermal-covers, protects, waxy coating (epidermis) 2. Vascular- xylem and phloem; support, transport 3. Ground - bulk of young plant, fills spaces between epidermis and vascular. Photosynthesis, storage, support. Types of ground tissue: Cortex - in root,cells store food, take up water & minerals. Endodermis - selective barrier in cortex- determines which substances pass between cortex and vascular tissue. Pith - fills center of stem in dicots, food storage. (Con’t.)