Anatomy, Morphology, & Growth of Angiosperms – Ch. 5-8 BOT 101 Anatomy, Morphology, & Growth of Angiosperms – Ch. 5-8

Two plant groups: monocots & dicots BOT 101 Two plant groups: monocots & dicots

Structure Reflects Function BOT 101 Structure Reflects Function http://www.fugu-sg.org/~elia/cambodia/templesfacesweb/pages/A3_Embracing_Roots.htm

Structure of a plant determined by: BOT 101 Structure of a plant determined by: Genetics Environment – two time scales: Long-term: Short-term: plasticity = wide range of phenotypes for each genotype. Allows plants to adjust to changing environment (ex. Shorter plant in dry year so that it can still reproduce)

Muscle cell Cells Tissues Muscle tissue Organs Heart BOT 101 Muscle cell Cells Tissues Muscle tissue Organs Heart Circulatory system Systems

Three organs: Roots, stems, leaves BOT 101 Three organs: Roots, stems, leaves Roots– Store food (carbos from photosynthesis) to be used for flowering & fruiting Covered with root hairs – increased surface area for absorption

BOT 101 Fig 35.2

Modified Roots – Fig 35.4 Prop roots Aerial strangler roots BOT 101 Prop roots Aerial strangler roots Sweet Potato – storage root Modified Roots – Fig 35.4 Buttress roots Pneumatophores

2. Stems/shoots Support, transport Some photosynthesis BOT 101 2. Stems/shoots Support, transport Some photosynthesis Two types of shoots Vegetative – Reproductive – Two parts of stem: Node – Internode – stem segments between nodes

BOT 101 Two types of buds Terminal bud – contains a shoot apical meristem; shoot growth is concentrated here Axillary buds – Apical dominance = the presence of an apical bud inhibits the growth of axillary buds. -remove or depress apical bud, axillary buds begin to grow.

Modified Shoots (stems): BOT 101 Modified Shoots (stems): Stolons – Rhizomes – Bulbs – swollen underground shoots Tubers – swollen rhizomes Asexual, vegetative propagation Stores food for later growth

BOT 101 Fig 35.5

3. Leaves – main photosynthesis organs BOT 101 3. Leaves – main photosynthesis organs http://www.knotweed.co.uk/japknot_Info.htm

BOT 101 Modified leaves Compound, doubly compound – why??

BOT 101 Tendrils Fig 35.7 – Modified leaves Spines Succulents

Compound leaf = divided into distinct units called leaflets BOT 101 Leaf types: Simple leaf = Compound leaf = divided into distinct units called leaflets

Four types of leaf arrangement: Acaulescent – BOT 101 Four types of leaf arrangement: Acaulescent – Alternate – Opposite – leaves borne across from each other at the same node Whorled – 3 or more leaves arising from the same node.

BOT 101

Three main tissues: Dermal, Vascular, Ground BOT 101 Three main tissues: Dermal, Vascular, Ground Fig 35.8

Dermal tissue or epidermis BOT 101 Dermal tissue or epidermis Root hairs are specialized epidermal extensions Secretes waxy cuticle of the leaf

BOT 101 2. Ground Tissue fills the space between dermal and vascular tissue systems. Diverse functions: pith In dicots: cortex

BOT 101 3. Vascular Tissue function in transport between roots & shoots, and structural support of plant Xylem: Phloem: Food transported to roots & non-photosynthetic parts such as the flowers

BOT 101 The Plant Cell Fig 7.8

5 Differentiated Plant Cell Categories BOT 101 5 Differentiated Plant Cell Categories Parenchyma Collenchyma Schlerenchyma Water-conducting cells of the xylem Sugar-conducting cells of the phloem

BOT 101 1. Parenchyma thin and flexible cell walls

BOT 101 2. Collenchyma Usually grouped in strands to support young parts of plants without restraining growth Flexible, elongate with growing shoots

3. Schlerenchyma May be dead at functional maturity – ??? BOT 101 3. Schlerenchyma May be dead at functional maturity – ??? cell walls left behind as skeleton

BOT 101

4. Water conducting cells of the xylem: BOT 101 4. Water conducting cells of the xylem: 2 types: tracheids & vessel elements

BOT 101 Tracheids Water flows from cell to cell (laterally) through pits in cell wall Support function

Vessel Elements End walls are perforated for free flow of water BOT 101 Vessel Elements End walls are perforated for free flow of water More efficient as water conductors than tracheids

BOT 101 Fig 35.9

5. Sugar-conducting cells of the phloem BOT 101 5. Sugar-conducting cells of the phloem Sieve-tube members: Lack a nucleus, ribosomes, vacuole Cells separated by perforated sieve plates – allow sugar movement

BOT 101 Fig 35.9

Growth & Development BOT 101 http://www.cneccc.edu.hk/subjects/bio/album/Chapter20/PLANT_GROWTH.html

BOT 101 Development =

Three processes of development: BOT 101 Three processes of development: Growth = Cellular differentiation = generation of different cell types Morphogenesis – creation of body form & organization.

BOT 101 1. Growth Cell division no expansion

BOT 101 Growth = due to water uptake in the vacuole

BOT 101 Fig 35.24

BOT 101 Cell division Occurs in only in meristems!

Meristems = Two types of meristems: Apical meristem – BOT 101 Meristems = Two types of meristems: Apical meristem – Lateral meristems – extend lengthwise along the axis of the stem & roots. Responsible for growth in girth in older parts of the plant (called secondary growth). Exist only in perennials

BOT 101 Fig 35.10

Primary Growth of Roots BOT 101 Primary Growth of Roots Root cap – layer of cells that protect the RAM as it pushes through the soil

BOT 101 Fig 35.12

Arrangement of Primary Tissues in Roots BOT 101 Arrangement of Primary Tissues in Roots Epidermis – Stele – Ground tissue – mostly parenchyma cells of the cortex – area between the stele & epidermis; stores food & takes up minerals. Endodermis – single cell layer between cortex & stele. Selective barrier for uptake of soil solution contents into vascular system.

Eudicot/Gymnosperm root cross section BOT 101 Eudicot/Gymnosperm root cross section Epidermis Endodermis Cortex Stele xylem phloem Fig 35.13

Primary Growth of Shoots BOT 101 Primary Growth of Shoots Bud = cluster of leaf primordia created by meristem. No internodes Lateral branches arise from axillary buds

BOT 101 Fig 35.15

Primary tissue arrangement of stems BOT 101 Primary tissue arrangement of stems Ground tissue = pith & cortex

Eudicot/Gymnosperm stem cross section pith BOT 101 Eudicot/Gymnosperm stem cross section pith phloem cortex xylem epidermis Fig 35.16 Schlerenchyma cells

Tissue arrangement of leaves BOT 101 Tissue arrangement of leaves 3 parts: Upper & lower epidermis – tightly interlocked cells, secrete waxy cuticle. Contains stomata flanked by guard cells Vascular tissue – Mesophyll – ground tissue between upper & lower epidermis

BOT 101 Fig 35.17

Secondary Growth Two lateral meristems: BOT 101 Secondary Growth Two lateral meristems: Vascular cambium – produces secondary xylem (= wood) & phloem Cork cambium – replaces the epidermis with cork: tough, thick cover for stems, roots.

Secondary growth of stems BOT 101 Secondary growth of stems Vascular cambium – layer of cells between primary xylem & primary phloem. Puts on successive layers of secondary phloem to outside & secondary xylem to inside =====> stem widens Wood = accumulation of secondary xylem. Dead at maturity, contains lignin

BOT 101 Cork cambium “bark” = Cork continually sloughs off

BOT 101 Fig 35.18

BOT 101

BOT 101 Fig 35.20

Three types of life cycles: BOT 101 Three types of life cycles: Annual – Biennial – complete life cycle in two years (first year = vegetative, second year = reproductive). Some need a cold winter period to initiate flowering from vegetative state. Ex. carrots Perennial – live year after year, do not die after reproduction. Examples: trees, shrubs, some grasses. Causes of death = fire, disease