Transcript Part 6
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 cortexdetermines which substances pass between cortex and vascular tissue. Pith - fills center of stem in dicots, food storage. (Con’t.)