Survey
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Download Roots
Document related concepts
no text concepts found
Transcript
4/24/2014 BI 103: Plant-Animal A&P • Moncots vs Dicots • Roots Lec 3 Learning Objectives What is the function of the plant root? How are specific cells and tissues adapted in the root in order to help it function? How are tissues in the root different from the leaves & stem? How does the root filter water? What are examples of specialized roots? Describe mutualisms plant roots may have with fungi & bacteria. 1 4/24/2014 Angiosperms, the flowering plants fall under two groups: Monocots or Dicots Plant Anatomy: Vegetative Organs Leaves: Photosynthesis Gas exchange Light absorption Stem: Support Transport Storage Roots: Anchorage Storage Transport Absorption Form = Function 2 4/24/2014 External Anatomy of a Root Root Cap -protects the apical meristem as the root pushes through the soil. Root Hairs increase the surface area of the root. Internal Anatomy root hair epidermis cortex endodermis of cortex pericycle xylem phloem vascular cylinder apical meristem Fig. 43-13 root cap 3 4/24/2014 Functions of Roots Roots 1) Anchor the plant 2) Absorb & filter water 3) Absorb minerals 4) Store surplus sugars 5) Transport water, minerals and sugars and hormones 6) Produce some hormones 7) Interact with soil fungi and bacteria Organs: ROOT DICOT MONOCOT 4 4/24/2014 Organ: Root 1. Epidermal Epidermis Endodermis Root hairs 2. Meristematic Pericycle 3. Ground Parenchyma 4. Vascular Xylem Phloem 5 4/24/2014 Organ: Root 1. Epidermal Epidermis Endodermis Root hairs 2. Meristematic Pericycle 3. Ground Parenchyma 4. Vascular Xylem Phloem 1. Epidermal tissue in roots A. Epidermis Lacks waxy cuticle B. Root hairs Increase surface area for absorption C. Endodermis Contains casparian strip made of suberin Filters water 6 4/24/2014 Dermal tissue in roots Mineral and Water Uptake by Roots vascular cylinder cortex epidermis air soil particles pericycle xylem endodermis 5 water 4 3 1 2 root hair plasmodesmata cell walls (a) Pathways of mineral and water uptake endodermal cells Fig. 43-17 Casparian strip (b) Endodermal cells, showing the Casparian strip 7 4/24/2014 Organ: Root 1. Dermal Epidermis Endodermis Root hairs 2. Meristematic Pericycle 3. Ground Parenchyma 4. Vascular Xylem Phloem 2. Meristematic A. Pericycle - Outer boundary of vascular cylinder – Continues to divide, even after mature – Forms lateral (branch) roots and part of the vascular cambium Lateral root formation 8 4/24/2014 Organ: Root 1. Epidermal Epidermis Endodermis Root hairs 2. Meristematic Pericycle 3. Ground: “Cortex” Parenchyma 4. Vascular Xylem Phloem 3. Ground tissue A. Cortex--Region of ground tissue B. Made up of parenchyma cells between epidermis and vascular cylinder Functions: Mostly stores food In the form of starch 9 4/24/2014 Organ: Root 1. Epidermal Epidermis Endodermis Root hairs 2. Meristematic Pericycle 3. Ground: “Cortex” Parenchyma 4. Vascular Xylem Phloem Root Types Tap Fibrous Adventitious - prop - butressed - aerial 10 4/24/2014 Taproots and Fibrous Roots Fig. 43-12 Prop Roots Example: Corn - Prop roots support plants in high wind 11 4/24/2014 Buttress Roots Stability in shallow soil --Tropical Trees Aerial Roots Orchids Velamen roots, with epidermis several layers thick to reduce water loss Ivies (English ivy, Virginia creeper) - Aerial roots aid plants in climbing 12 4/24/2014 Specialized roots Contractile Roots Pull plant deeper into the soil Example: Trillium ovatum (Family: Liliaceae) Specialized roots: Haustoria Parasitic roots Cusucuta spp. Aka ‘Dodder’ 13 4/24/2014 Specialized Roots Pneumatophores In plants with roots growing in water Spongy roots that extend above the water’s surface Enhance gas exchange between atmosphere and subsurface roots Mangrove pneumatophores Mycorrhizae: A Root–Fungus Symbiosis Fig. 43-19 14 4/24/2014 1. Endomycorrhizal fungi Internal fungal associations Also known as: vasicular-arbuscular 1. Endomycorrhizal fungi Internal fungal associations 15 4/24/2014 2. Ectomycorrhizal fungi External fungal associations 2. Ectomycorrhizal fungi External fungal associations 16 4/24/2014 Root Nodules House Nitrogen-Fixing Bacteria nitrogen-fixing bacteria within cortex cells of nodules Fig. 43-20 nodule epidermis 17
Related documents