chapter 35 plant anatomy 09 03 2015 Different types of plant cells Parenchyma cells o Found everywhere in the plant stem roots leaves etc o Do not have secondary cell walls o Primary walls are very thin and flexible o Specialized to hold things o Very large central vacuole Store water and nutrients Leads to the support of the plant o Will do most of the metabolic activity of the plant o Usually don t divide but they can Important in repair and replacement Collenchyma cells o Have more rigid primary walls but not really rigid o No secondary walls o No lignin o Important in the support of young plants and in the stems of non woody plants green o Capable of elongation Elongation a way that plant cells grow by taking up water only grows vertically Sclerenchyma cells o Important in support o Contain secondary cell walls with lignin o Found in areas of the plant that has stopped growing Can be dead but are still used for support o Non living cell wall left after the cell dies o Two types Fibrous cells Sclereid cells any kind of nut shell Tracheids o Found in all vascular plants o Angiosperms also have vessel elements o Make up xylem o Many pit from the plasma desmata o These cells are dead Sieve plate sieve tube cells o Found in the phloem o Contains pores o Not dead like xylem cells but only have cytoplasm Companion cell o Found in the phloem o Life support system for sieve tube cells Different types of plant tissues Dermal tissue o Covering everything o Skin of the plant o Single layer of cells that are tightly packed o Used for protection o Associated with the cuticle o In plants that don t have secondary growth they only have dermal tissue Periderm replaces dermal tissue when plants have secondary growth Ground tissue o Made up of parenchyma cells usually o Used for storage support and photosynthesis o Found in roots stems and leaves Vascular tissue o Xylem and phloem o Runs through the whole plant Meristem tissue Found in areas of the plants that are growing Go through steps to determine what they will become Become different tissues through three starting points o Protoderm dermal o Precambium vascular xylem phloem o ground meristem ground apical or axial meristem creates plant growth buds will for and plant ligatures will grow off of them plant continues to grow tall and wide overall plants have indeterminate growth plant can grow as long as it lives as long as it has meristematic tissue leaves and parts of trees can have determinate growth annuals seed to seed in 1 year grow bloom and set seed in 1 year biennials 1st year they grow 2nd year they seed and die carrots foxgloves queen Anne s lace perennials grow flower seed and repeat for years upon years daffodils day lilies parts of the root bottom to top root cap o protection the meristem o secrets a slimy material to help it move through the soil zone of cell division o includes apical meristem o mitosis occurring here zone of cell elongation o growing by increasing the length of the cells o can increase by 10x their size zone of differentiation o separating cell types and tissue no distinct boarders they overlap and merge with each other root hairs o increase surface area for water intake cross section of eudicot root epidermis cortex o ground tissue o mostly used for storage endodermis o ground tissue o single packed layer of cells o the gate keeper of the cell vascular cylinder o vascular system of the plant pericycle o directly under endodermis o meristematic tissue o this is where lateral roots are made figure 35 15 o connects the roots to the vascular system xylem o spoke looking larger cells toward the middle of vascular cylinder phloem o smaller cells closer to the outside of the vascular cylinder cross section of a monocot root all the same except the arrangement of the xylem and phloem has a core of parenchyma cells in the middle of the vascular tissue there are piths in the middle of eudicot stems ring of vascular bundles vascular bundles in monocot stems are scattered throughout XYLEM IS ALWAYS INTERNAL TO PHLOEM Monocots do not have secondary growth Two types of meristematic tissue involved in secondary growth Vascular cambium o Every year it makes new xylem inside and phloem outside o Newest cells are always closer cambium Known as the secondary phloem xylem o Primary gets pushed out o DOESN T MOVE Cork cambium lateral meristem xylem makes the rings of trees the fatter cells are known as spring early wood larger because more water the smaller cells are known as summer late wood less water available during this time two types of xylem sap wood o young xylem o carries water heart wood o lots of resin o located in the center of the tree o the oldest xylem in the tree o not carrying water anymore used for support vascular rays pipelines through the xylem to communicate with phloem XYLEM ACCUMULATES AND PHLOEM DOSEN T Periderm Cork cambium o Divides to make cork outside of the cork cambium o Replaces dermal tissue o Makes new cork cambium behind it o Destroys the old phloem o Moves inward o Cork made outward Cork o Renewed more is made every year o Water proof o Suberin cuticle of cork o Lenticles cells that die and allow for gases to travel through the cork Bark Made up of phloem cork and cork cambium Goes a decent way into the tree Leaves Stomata stoma means mouth o Guard cells open and close stomata Ground tissue has two types o Palisade mesophyll o Spongy mesophyll Veins contain xylem and phloem FIGURE 35 18 09 03 2015 09 03 2015