Plant Structure

• they are sessile
• they have indeterminate growth
• their support system uses organic, inert molecules
• they store different types of energy

• anchorage
• storage
• absorption

• single main root with lateral roots growing off of it
• typical of eudicot
• adapted for deep soils

• adapted for shallow anchorage
• isodiametric
• may be adventitious - radical dies, roots emerge from stem itself
• typical of monocots

• prop - comes out of root from stem (adventitious)
• storage
• strangling "aerial"
• buttress - supporting
• pneumatophores - in swampy areas, surface to "breathe" air

• nodes - where leaves emerge, &
• internodes - stem between nodes

• terminal bud - at top of stem, main bud
• axillary buds - above nodes, on the axis; termination of teminal bud will stimulate lateral growth

• stolon - grows horizonally and asexually; above ground
• bulbs - short, undergound; fleshy leaves surround it (ex: radish)
• tubers - grow at end of rhizomes (ex: potato)
• rhizomes - underground, horizontal; stem structures grow from it

blades are connected to stem by a petiole

leaves emerge from stem base, forming a sheath

• tendrils - demonstrate response to touch; may coil
• spines - nonphotosynthetic; defensive purposes (ex: cactus)
• storage - for water, nutrients (ex: jade, aloe)
• bracts - associated with flowers, colorful, main photosynthetic organ (ex: poinsetta)
• reproductive - serrated edges that grow additional leaves and roots; allots asexual reproduction

• thin primary wall, not lignified
• useful for storage
• no chloroplasts, not much inside except for huge vacuoles
• isodiametric
• live at maturity

• modified type of parenchyma cell with chloroplasts
• usually found in middle of leaves

• unevenly thickened primary cell walls
• elongated cells
• provide support for actively growing cells
• living at maturity

• tough, fibrous
• lignified secondary cell wall to help maintain shape (fibrous, barrel, star)
• dead at maturity; achieves correct shape/size then undergoes apoptosis

• not very porous
• structure eliminates hyrdolic and turgor pressure
• interior to primary cell wall
• strengthened with lignin/cellulose
• thickness depends on what it differentiates into

• outer covering of leaves, stems, roots
• on leaves, may secrete cutin

• consist of xylem and phloem
• transportation tissues

• neither dermal nor vascular
• provides bulk and support
• made of all cell types
• cortex - found exterior to vascular tissue
• pith - interior to vascular tissue

• cells that undergo constant mitotic division
• consist of differentiating cells
• phloem points outside, xylem points inside
• apical meristems and lateral meristems

• move water and dissolved inorganic nutrients
• modified sclerenchyma
• conducting elements are vessels and tracheids
• vessels: common in angios; wider, more efficient; have end plates - water can move easier from one element to another
• tracheids: in both angios and gymnos; narrow, spindle-shaped; assist in going through secondary cell walls

• transport of photosynthate (dissolved sucrose)
• not necessarily a one-way flow
• modified parenchyma
• conducting elements are sieve cells (gymnos) and sieve-tube members (angios)
• sieve cells: living, but not a full compartment of organelles; albunious cells are helper cells
• sieve-tube members: missing many vital organs, but living; barrel-shaped for good efficiency; companion cells assist with organelle functions
• sieve plates - perforated plates; sap flows through these to adjacent cells

• on root and shoot tips
• primary growth for herbaceous plants

• secondary growth in woody plants
• increase in girth, width
• meristems are the vascular and cork cambiums

• zone of cell division - includes the root apical meristem and its derivatives; new cells are produced
• zone of maturation - most of the growth in roots; cells elongate and push root down further into soil; cell differentiation begins to become noticable
• zone of differentiation - cells become distinct cell types (at topmost part)

• monocots: parenchyma (pith) in center; core is surrounded by ring of xylem (inside) and ring of phloem (outside)
• eudicots: xylem (inside) and phloem (outside) in center core; stele is the vasculer cylinder appearing as a lobed core

epidermis --> cortex --> endodermis --> pericycle --> vascular cylinder (phloem, xylem)

epidermis --> cortex --> endodermis --> pericycle --> phloem --> xylem --> pith(core of parenchyma cells)

• special layer of cells with super thick walls that are water proof and lignified
• selective barrier for stele
• modified parenchyma
• innermost layer of cortex

• leaves develop from leaf primordials - projections along the side of the apical meristem
• shoot elongation is due to lengthening of internode cells just below the shoot tip
• branching arises from activation of axillary buds
• intercalary meristems allow damaged leaves to rapidly regrow

epidermis --> [maybe] collenchyma cells --> cortex --> vascular bundle (sclerenchyma --> phloem --> xylem) --> pith

epidermis --> collenchyma cells --> scattered vascular bundles within mass of ground tissue

upper epidermis (cuticle --> layer of dermal tissue interrupted by stomata and guard cells) --> palisade mesophyll (elongated chlorenchyma cells) --> vascular tissue (surrounded by bundle-sheath cells) --> spongy mesophyll (contains air spaces) --> lower epidermis

• aid from lateral meristems (cambiums)
• only in woody plants
• builds on primary growth plan
• typical in eudicots and gymnos

• provides protective layer for stem
• cork on the exteriror
• corticle cells on the interior
• entire complex called bark (which also includes secondary phloem)
• develops within cortex
• replaces epidermis
• periderm (cork cambium) secretes suberin into cell walls that makes the bark water proof

• produces secondary phloem to exterior and secondary xylem to interior
• youngest tissue closer to vascular cambium, older tissue towards center of trunk
• phloem layers are much narrower

everything outside of vascular cambium : periderm (cork cambium and cork) and secondary phloem

loosely arranged cork cells that oxygen can diffuse through

taking an entire ring of bark off of the tree can kill it because of secondary phloem removal