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Chapter 3: The Plant Body (Vegetables: Edible Plant Organs (Plants that…

- - - - meristem:
        area of actively dividing cells in plants
      - cells in meristem give rise to various tissue types that make up a plant
    - - dermal tissue:
        tissue that covers surfaces in plants
      - ground tissue:
        includes primary tissues of parenchyma, sclerenchyma, and collenchyma that make up much of the bulk of the primary plant body; function in support, photosynthesis, and storage; also known as fundamental tissu
      - vascular tissue:
        tissue that is specialized for the long-distance transport of water or photosynthesis products; xylem and phloem
    - - tissues that develop apical meristems part of primary growth of plant; give rise to leaves and nonwoody stems and roots
        
        primary growth:
        growth in length due to the activity of the apical meristems of shoot and root
      - some plants have additional meristematic tissues that contribute to increases in diameter
        
        vascular cambium:
        meristematic tissue that gives rise to secondary xylem and secondary phloem
        
        cork cambium:
        meristematic tissue that produces cork cells on its outer surface and phelloderm on its inner surface
        
        tissues from vascular cambium and cork cambium part of secondary growth
        
        secondary growth:
        the increase in girth of stems and roots; produced by the activities of the vascular cambium and cork cambium
  - - - epidermis:
        outermost tissue in all young and nonwoody plant organs
        
        usually single layer of flattened cells; epidermal cells in leaves/stems secrete cutin
        
        cutin:
        waxy material secreted by epidermal cells
        
        cuticle:
        waterproof layer of cutin on leaves and nonwoody stems
        
        prevents evaporative water loss from the plant by acting as waterproof barrier
    - - trichome:
        an epidermal appendage, such as a hair or a scale
        
        may be abundant enough to give fuzzy texture
        
        may also be glandular, often imparting an aroma when they are brushed
    - - stoma:
        (pl: stomata) a minute opening, bordered by guard cells, in the epidermis of leaves and stems
        
        exchange gases such as carbon dioxide, oxygen, and water vapor
      - guard cell:
        one of a pair of specialized cells in the epidermis that regulate the opening and closing of stoma
        
        pair of sausage-shaped cells that occur on each side of pore
        
        the only epidermal cells with chloroplasts
      - stomata and guard cells can also be found in epidermis of some stems
    - - periderm:
        protective tissue that replaces the epidermis after secondary growth begins; includes the cork, the cork cambium, and sometimes other cells
        
        make up outer bark on mature trees
        
        continually produced by cork cambium as tree grows in girth
      - cork mainly made up of dead cells whose walls contain suberin
        
        suberin:
        a fatty material found in the cell walls of cork cells and the Casparian strip of the endodermis
        
        percents water loss and protects underlying tissues
  - - - most versatile, but usually thin-walled, 14-sided polygon
      - usually loosely arranged with many intercellular spaces
      - serve many functions; photosynthetic cells in leaves and green stems and storage cells in all plant organs
    - - primary support tissue in young plant organs
      - found in stems, leaves, petals
      - elongated with unevenly thickened primary cell walls, often with walls thickest at corners
      - often found tightly packed together just below epidermis
    - - two cell types
        
        fiber:
        long and narrow sclerenchymous cell; functions in support; an important dietary component that provides bulk; component of fabrics, ropes, and paper
        
        nonliving at maturity and have thickened secondary walls
        
        sclereid:
        a sclerenchyma cell with a thick, lignified secondary wall having many pits; viable in form but not usually elongated
        
        major function to provide mechanical support/protection
  - - - in leaf, vascular tissues are the veins
        
        vein:
        a vascular bundle that forms part of the conducting and supporting tissue of a leaf
      - form a continuum throughout plant, allowing unrestricted movement of materials
    - - xylem:
        the vascular tissue specialized for the conduction of water and minerals; consists of tracheids and vessel elements, fibers, and parenchyma cells
        
        conducts water and minerals from roots upwards
        
        tracheid and vessel elements are water-conducting cells in xylem; both have secondary walls and at maturity are dead and consist only of cell walls
        
        tracheid:
        an elongated, tapering xylem cell that is specialized for conducting water and support with lignified pitted walls
        
        long and thin with pits in walls; also function in support
        
        vessel element:
        one of the cells forming a vessel and characterized by a perforation plate
        
        often short and wide and have horizontal end walls with large openings; side walls have numerous pits
        
        attached end to end and form long, pipe-like vessel
        
        vessel:
        a tubelike column of vessel elements that are connected by open end walls and are specialized for the condition of water and minerals
        
        both tracheids and vessel elements found in angiosperms, but only tracheids occur in other plants with vascular tissue
        
        fibers present in xylem, where provide more support
        
        parenchyma cells, also occur in xylem, are only living and metabolically active cells in tissue
        
        can be either primary or secondary
        
        primary xylem originates from apical meristem
        
        secondary xylem comes from vascular cambium (secondary xylem is wood in trees)
      - phloem:
        the vascular tissue that conducts organic materials synthesized by the plants
        
        transports organic materials synthesized by the plant
        
        cells involved in transport of organic materials in phloem called sieve tube members
        
        sieve tube member:
        a phloem cell characterized by a sieve plate and enucleate condition; specialized for the conduction of products of photosynthesis
        
        living cells with only primary walls, but nucleus and some organelles degenerate as it matures
        
        end walls have several to many large pores, called sieve plates
        
        sieve plate:
        the perforated wall area in a sieve tube member
        
        allow plasmodesmata, cytoplasmic connections, to occur between adjacent sieve tube members, provide channels for conduction
        
        sieve tube:
        a long tube specialized for the conduction of food materials (products of photosynthesis) and consisting of several to many sieve tube members
        
        adjoining each sieve tube member is companion cell, which is physiologically and developmentally related to its sieve tube member
        
        companion cell:
        phloem cell associated with a sieve tube member
        
        smaller companion cells have large nucleus that controls adjacent sieve tube members through numerous plasmodesmata that connect the two cells
        
        companion cells involved in loading/unloading of organic materials for transport
        
        both fibers and parenchyma cells also found in phloem
        
        both primary and secondary phloem occur and are produced by same things that produce them in xylem
- - - - major differences are in flower and seed, but anatomical differences can also be seen in stems, roots, and leaves
    - - outermost tissue is single layer of epidermis
      - then, 2-3 layers of sclerenchyma for support
      - vascular bundles scattered throughout stem
        
        vascular bundle:
        a strand of tissue containing primary xylem and primary phloem, often surrounded by a bundle sheath
        
        bundle sheath:
        sheath of parenchyma or sclerenchyma cells surrounding the vascular bundles in leaves
        
        parenchyma fills rest of cell
    - - herbaceous:
        refers to nonwoody plants
        
        vascular tissue occurs as ring of separate vascular bundles
        
        each vascular bundle contains both xylem (toward center of stem) and phloem (toward outside of stem)
        
        ring of vascular bundles surrounds the pith
        
        pith:
        the central tissue of a dicot stem, consisting of parenchyma cells
        
        central area of ground tissue, made of parenchyma cells
        
        on other side of ring, toward outside of stem, is cortex
        
        cortex:
        parenchymous tissue, the region between the epidermis and vascular tissue in an herbaceous root or stem
        
        another region of ground tissue
        
        consists mainly of parenchymous tissue, but may have fibers
        
        between vascular bundles, ground tissue of pith and cortex is continuous
        
        in some plants, support tissue (sclerenchyma or collenchyma) can be found beneath epidermis
      - woody stems:
        stems that undergo secondary growth
        
        vascular tissue, especially the xylem, is much more extensive and makes up the bulk of the stem
        
        pith occupies center of stem, similar to how it does in nonwoody dicots
        
        surrounding pith are rings of secondary xylem, representing xylem formed by vascular cambium during one growth season
        
        annual ring:
        ring of xylem in woody stem composed of springwood and summerwood that corresponds in temperate regions to a chronological year
        
        due to different sizes of cells formed through growing season- springwood formed when water is more abundant and has noticeably larger cells, appears lighter
        
        springwood:
        the cells in the secondary xylem that are formed early in the season, usually with wide vessels (angiosperms) or wide tracheids (gymnosperms); also called early wood
        
        summerwood:
        the cells in the secondary xylem that are formed late in the season, usually with few vessels (angiosperms) or narrow tracheids (gymnosperms); also called late wood
        
        surrounding outermost ring of xylem is vascular cambium, the meristematic tissue that produces both secondary xylem (toward inside) and secondary phloem (toward outside)
        
        no annual rings present in phloem because small amount produced compared to xylem
        
        vascular ray:
        sheet of parenchyma that extends radially through the wood, across the cambium, and into the secondary phloem; rays are produced by the vascular cambium and function in lateral transport
        
        seen across both xylem and phloem
        
        composed of parenchyma cells and involved in radial transport of materials
        
        small band of cortex can be found outside phloem
        
        in older trees, cortex is completely replaced by periderm (cork)
        
        thickness/texture of periderm depend on type of tree
  - - - taproot:
        a relatively large primary root that gives rise to smaller, lateral roots
        
        can be enlarged for storage, as seen in carrots/turnips/beets
      - fibrous roots:
        root system with several main roots; common to many monocots
    - - root caps:
        a thimble-shaped group of cells found at the tip of roots; protects the meristem
    - - zone of cell division:
        region of root tip in which cell division takes place
    - - zone of elongation:
        region of root tip in which newly formed cells elongate or grow
    - - zone of maturation:
        region of root tip in which newly formed cells differentiate into the various tissues that comprise the root
      - in zone of maturation, vascular tissue found in center of root, making up stele, or vascular cylinder
        
        stele:
        the vascular cylinder; vascular tissue making up the central cylinder of roots
        
        vascular cylinder:
        the stele; vascular tissue making up the central cylinder of roots
        
        in center of stem is xylem, usually in star-shaped configuration; bundles of phloem between arms of xylem
        
        in monocot roots, pith is present and encircled by alternating bundles of xylem and phloem
        
        outermost layer of cells in stele is pericycle
        
        pericycle:
        root tissue sandwiched between the endodermis and the phloem; the outermost layer of the stele; meristematic region that gives rise to branch roots
      - surrounding the stele is the cortex, composed of parenchyma cells, which are sites of storage
        
        cortex usually quite large, making up bulk of root
        
        endodermis:
        innermost layer of the root cortex surrounding the stele; many of the endodermal cells have Casparian strips
        
        Casparian strip:
        water-impermeable strip of suberin found in the transverse and radial walls of endodermal cells
        
        faces of cell wall next to cortex and stele do not have Casparian strip, meaning water/minerals must pass through endodermal cells, not between them
        
        outermost layer is epidermis, extensions of epidermal cell called root hairs
        
        root hair:
        a root epidermal cell that functions in water absorption
        
        greatly increase surface area and are sites of maximum water and mineral absorption
    - - bald cypress, native to North America, is conifer commonly found in freshwater swamps
        
        produces pneumatophores that project about water surface and contain aerenchyma tissue
        
        pneumatophores:
        aerial outgrowth of submerged root system in the bald cypress; conduct air with oxygen to root cells
        
        without pneumatophores, roots would not have oxygen for cellular respiration and would not survive in floods
        
        aerenchyma:
        type of parenchyma tissue that has many large, intercellular spaces for the passage of air and exchange of gases
      - many tropical rain forest orchids are epiphytes
        
        epiphyte:
        plant that grows on top of another plant for support and position
        
        epiphyte orchids have aerial roots, which are at first green and photosynthetic but later become covered with velamen
        
        velamen:
        outgrowth of epidermis of aerial orchid roots; prevents desiccation
        
        waterproofs aerial root against water loss
        
        prop roots:
        aerial roots which sprout from the nodes of stems and then grow into the ground to anchor and support stems
        
        provide aboveground support and belowground anchorage and conduct water/dissolved nutrients to stem
      - contractile roots:
        found in plants with extremely short stems; cortical cells contract in height pulling the root down into the ground ensuring that the stem remain at ground level or slightly below
        
        found in common dandelion and other plants with short stems
        
        cells in upper cortex of root change shape, expanding in width but losing more than half height
        
        shape change pulls stem down, either keeping it at soil level or slightly below
      - plants that have woody stems have extensive secondary xylem and annual rings in roots and stems
        
        major difference between woody root and woody stem is that woody root has no pith
  - - - ideal for photosynthetic process
      - petiole:
        the stalk of a leaf
        
        aka leaf stalk, connects leaf blade to stem and transports materials to/from blade
        
        some leaves have no petiole, blade is attached directly to stem
      - stipule:
        a small appendage found in pairs at the base of leaves
        
        varies in form; sometimes leaflike, sometimes thornlike
      - node:
        the region of a stem where leaves or branches arise
        
        place where petiole attached to stem
      - internode:
        region on a stem between nodes
    - - alternate arrangement:
        one leaf borne per node
      - opposite arrangement:
        two leaves borne per node and arranged across the stem from each other
      - whorled arrangement:
        three or more leaves per node
    - - simple leaf:
        a lead that is not divided into leaflets
      - compound leaves:
        a leaf with a blade divided into separate leaflets
        
        leaflet:
        a subdivision of a leaf blade
        
        pinnately compound leaf:
        leaflets attached on both sides of a common axis
        
        when leaflets occur on featherlike pattern
        
        palmately compound leaf:
        leaflets radiate from a common point
    - - axil:
        upper angle between leaf and stem
      - bud:
        embryonic shoot of a plant; may be composed of embryonic leaves or flowers or be mixed
        
        buds located in axil
        
        auxiliary buds found only at base of leaves, so auxiliary buds are associated with leaves
    - - parallel venation:
        principle veins are parallel to one another; characteristic of monocot leaves
        
        typical of monocot leaves because vascular bundles are arranged in parallel lines running the length of the blade
      - dicots have net or reticulate venation where vascular tissue is highly branched, forming network throughout blade
        
        net venation:
        the netlike pattern of branching of veins on a leaf blade; also known as reticulate venation; characteristic of most dicot leaves
        
        reticulate venation:
        netted venation; the arrangement of veins in a leaf that resembles a net; characteristic of dicot leaves
    - - epidermal cells covered in waxy cuticle and guard cells and stomata distributed throughout epidermis
      - thousands of stomata occur in both upper and lower surfaces, but number and distribution vary considerably
        
        at higher altitudes, number of stomata per leaf increase to compensate for lower carbon dioxide in thinner air
    - - mostly composed of photosynthetic parenchyma cells that may be of two types
        
        palisade parenchyma:
        parenchyma cells in the leaf mesophyll characterized by uniform rows of tightly packed cells with many chloroplasts beneath the upper epidermis
        
        cells are tightly packed, columnar cells lying just beneath upper epidermis
        
        spongy parenchyma:
        part of the leaf mesophyll; cells that are loosely arranged and contain chloroplasts
        
        loosely packed, spherical cells with many large intercellular spaces
        
        scattered within mesophyll are vascular bundles that bring water up to leaf and carry away sugars produced by mesophyll cells
    - - surface of leaf epidermal cells is microscopically bumpy, covered with many minute projections
      - bumpy surface combined with especially thick waxy cuticle make leaf surface super water-repellant
        
        hydrophobic:
        water-repellant molecules or surfaces
        
        water falling on leaf surface will form spherical droplet and be restricted to the crests of the epidermal cells
        
        water droplets perched on crests of leaf epidermal surface picked up dirt as they rolled off the epidermal peaks
      - water on water-loving surfaces spreads across the surface in large, flatter smears
        
        hydrophilic:
        water-attracting molecules or surfaces
  - - - narrow ring may indicate year of low rainfall or drought, wide rings indicate abundant rainfall
    - - arid climate prevents decay of dead trees
    - - dendroclimatology:
        study of the annual rings in trees in order to interpret climatic changes in the past
      - by studying rings of very old trees, can reconstruct major climatic changes; trying to determine if droughts occur in cyclical pattern
- - - - during first year, plant stores large amount of food in enlarged taproot, which we call the carrot
        
        carrots normally harvested after first growing season
      - during second summer, plant uses stored food in taproot to produce a flowering stalk
  - - - head lettuce- forms a dense, tightly packed head of leaves, as in iceberg lettuce
      - loose-leaf- nonheading, with ruffled leaves forming loose clusters
      - cos- form an upright, cylindrical head composed of long leaves
  - - - cladophyll:
        modified stem that resembles and functions as a leaf
  - - - most found in nutrient-poor soil, such as acid freshwater bogs
    - - traps are all modified leaves that offer various incentives, such as nectar or color
      - once insects are ensnared, digestive enzymes are released, and soon only the empty shell of the insect remains
    - - Venus Flytrap
        
        native to NC costal region
        
        each leaf is two-sided trap with trigger hairs on each side that, when touched, snaps shut tightly around the insect
        
        once trap closed, digestive enzymes begin their work and opens again after a few days
      - Sundew
        
        small plants that use flypaper-like leaves to trap insects
        
        glandular hairs on the leaf surface produce an adhesive that is like superglue
        
        insect sticks and is soon digested
      - Pitcher Plants
        
        leaf has evolved into a vase or pitcher shape that acts as a pitfall trap
        
        insects slip into a pool of rainwater that contains digestive juices
        
        leaves have ridges that insects can crawl across when lip is dry, but when it is wet, liquid fills the ridges and it becomes slippery