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Chapter 35.1-35.3 Study Guide
 In a plant, there is a root system and a shoot
system.
 The shoot system is comprised of stems and leaves.
Root: organ that anchors plants, absorbs minerals,
water, and stores carbs.
 Most eudicots and gymnosperms have taproots (1
main root).
 Most monocots/seedless vascular plants have
adventitious roots or fibrous root systems (many
small roots)
Root hairs: tips of roots absorb most water. They are
thin, tubular extensions of root epidermal cells.
Prop roots: In corn; support tall plants.
Storage roots: Store food and water
Strangling aerial roots: Descend from branches.
Buttress roots: Aerial roots that look like buttresses
Pneumatophores (air roots): Project above water for
oxygen (found in mangroves).
Nodes: Points at which leaves are attached
Internodes: stem segments between nodes
Stem: nodes and internodes
Auxiliary Bud: Structures that can form lateral branches
Apical Bud: Shoot tips (site of elongation).
 Apical buds receive more resources than auxiliary buds in terms of distribution.
In apical dominance, auxiliary buds are dormant.
 Removing apical buds breaks auxiliary buds from dormancy, so plants become bushier.
Rhizome: Horizontal shoot (stem) that grows underground.
Bulbs: vertical underground shoots with leaves.
Stolons: Horizontal shoots that grow along surface.
Tubers: Enlarged ends of rhizomes or stolons.
Leaf: Blade and petiole (stalk).
 Grass and many other monocots don’t have petioles. They form sheaths.
Tendrils: Plants use these to cling to support leaves
Storage leaves: store water.
Spines: Decrease surface area, provide protection, and don’t do photosynthesis
Bracts: Colorful leaves that surround flowers to attract pollinators.
Stele: Vascular tissue of roots and stem.
Parenchyma Cells: Typical plant cell.
 Mature ones have thin, flexible primary walls.
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Lack secondary walls.
Have large, central vacuoles.
Least specialized.
Synthesize/store products.
In leaves, perform photosynthesis.
In stems/roots, store starch.
Compose fleshy tissue of fruits.
Can divide/differentiate into other types of cells (e.g.
in repair).
Collenchyma Cells: Support young parts of plants
 Grouped in strands or cylinders
 No secondary walls
 Thick but uneven primary walls
 Young stems/petioles often have their epidermis
 Hardening agent, lignin, is absent from primary wall
 They are flexible and don’t restrain growth
 Elongate with stems and leaves
Selerenchyma Cells: Specialized for support and strengthening
 Have thick, secondary walls
 Strengthened by lignin
 Cannot elongate
 Focused in parts that stopped growing
 Many are dead at maturity
 Secondary walls are made before protoplast (living part) dies
 Two types of Sclerenchyma Cells
o Sclerids: Give hardness to nutshells, seed coats, etc.
 Have thick, lignified secondary walls
o Fibers: Usually in threads (used for rope)
 Long, slender, tapered
Two types of Water-Conducting Cells of Xylem
Tracheids: Found in xylem of most vascular plants
 Tubular, elongated
 Dead at maturity
 Long, thin, tapered
 Hardened with lignin
Vessel Elements: Align end to end to form micropipes or “vessels”.
 Wider, shorter, thinner walled, less tapered
 The ends have perforation plates, so water could flow
 Found in most angiosperms, few gymnosperms, and few seedless vascular plants
Both: When the protoplast disintegrates, nonliving cells conduit for water flows. There are piths
where there don’t exist secondary walls but exist primary walls. Water can travel through these.
Sugar-Conducting Cells of Phloem
 Alive at maturity
 In seedless vascular plants/gymnosperms, sugar/organic nutrients
travel through sieve cells (long, narrow).
 In angiosperms, nutrients transported through sieve tubes, which
consist of chains of sieve-tube elements or sieve-tube members.
 Sieve-tube elements: lack nucleus, ribosomes, distinct vacuoles,
cytoskeletal elements. Reduction allows nutrients to pass more
easily.
Cell walls are called sieve plates. They have pores to flow fluid.
 Companion Cells: Nonconducting cell. Connected to sieve tube
by channels (plasmodesmata). Its nuclei and ribosomes also
function for sieve-tube elements. Can also provide sugar.
Indeterminate growth: Growing all the time.
Determinate growth: Stop growing after certain size.
Annuals: Plants that complete life cycle in about a year.
Biennials: Have 2 growing seasons.
Perennials: Live many years.
Meristems: Embryonic tissue.
Apical Meristem: Located at tips of roots, shoots, auxiliary buds.
They make plants grow in length in Primary Growth. They
compose almost all growth in herbaceous plants (nonwoody).
Secondary Growth: Growth in thickness. Mostly in woody
plants caused by lateral meristems.
Vascular Cambium: Add layers of secondary xylem (wood) and
secondary phloem.
Cork Cambium: Replaces epidermis with thicker, tougher
periderm.
Initials: Cells that remain as source of new cells.
Derivatives: New cells displaced from meristems.
 Vascular cambium adds secondary xylem and phloem.
 Cork cambium adds secondary dermal tissue.
 Scars form because scales are produced during dormancy, and these are shed as scars during
spring (primary growth).
Primary Plant Body: parts not woody
Root cap: Located at the tip of roots.
 Protects apical meristem
 Secretes polysaccharides which start to lubricate growth in soil.
There is a zone of differentiation, zone of elongation, zone of division
 There are no sharp boundaries in these zones.
 In the zone of elongation, the cells elongate and push the tip farther
into the soil.
 In the zone of cell division, there is the root apical meristem and its
derivatives. New root cells are made.
 Water enters through the epidermis and root hairs.
Stele: Vascular cylinder with xylem and phloem.
 Xylem makes a “star” and phloem fill up spaces in eudicots.
 In monocots, the vascular tissue is a cone of parenchyma cells with
a ring of xylem and a ring of phloem.
 Xylem are closer to center.
 Central region is called pith.
Cortex: region between vascular cylinder and epidermis
Ground Tissue: Mostly made of parenchyma cells
Endodermis: Innermost layer of cortex. It’s one cell layer thick that forms boundary with
vascular cylinder.
Pericycle: Outermost layer of cortex. Lateral roots start from pericycle so that lateral roots
connect to vascular system.
Leaf Primordia: Finger-like projections alongside the sides of the apical meristem.
Apical Meristem: Leaves develop from this. Auxiliary buds develop from islands of
meristematic cells at base of leaf primordia.
Intercalary Meristem: Are at base of leaf blades and stem internodes. There is meristematic
tissue separate from the apical meristem.
Zone of Transition: Where vascular bundles from stem and root converge (near soil surface).
 Eudicots have vascular tissue as ring. Xylem
closer to middle than phloem.
 Monocots have vascular tissue scattered.
 Both eudicots and monocots have groundtissue mostly of parenchyma cells.
 Collenchyma cells sttrengthen stems.
 Sclerenchyma cells also strengthen stems (but
do not elongate).
Stomata: Pore that allows gas exchange between
leaf and air.
Guard Cells: Regulate opening/closing of stomata
Mesophyll: Ground tissue of leaf. (between upper
and lower epidermal alyer). Consists mainly of
parenchyma cells for photosynthesis.
Palisade mesophyll: Has 1 or more layers of elongated parenchyma cells.
Spongy mesophyll: Has parenchyma cells more loosely arranged, so gases can circulate.
Leaf traces: Connections from vascular bundles in stem pass through petioles into leaves.
 Veins (vascular bundles) branch throughout mesophyll.
Bundle Sheath: Protects veins. There is at least one layer of cells (usually parenchyma).