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Note that the following is a rudimentary outline of the class lecture; it does not contain everything discussed in class. Plant Diversity Cont. Angiosperms Angiosperm Advantages Advance Vascular Tissue Xylem – support and water transport – more efficient at water transport – Support Phloem Sieve cells Sieve tube members Flowers Fruits Angiosperm Life Cycle Sterile Flower Parts – the outer most part of the flower, leaf-like and green – usually delicate in texture; often colored Lecture 3 - Plant Diversity – often larger than sepals; may be shed soon after the flower opens – the swollen tip of the stalk supporting the flower Female Flower Parts – the female reproductive part of the flower, occupies a central position. – The female parts may consist of a single carpel or several carpels. Each carpel consists of three parts: – the pollen receptive part at the summit, which may be single, lobed or branched – the stalk like portion below the stigma – the enlarged portion at the base which contains one or more ovules or immature seeds Male Flower Parts – the male reproductive part of the flower, occupies a position inward from the petals. Each stamen consists of two parts – the sac-like part that contains the pollen BIOL 1030 2 Lecture 3 - Plant Diversity – the stalk that connects the anther to the floral axis or some other part Development of Male Gametophyte Development of Female Gametophyte Pollen Tube Growth & Double Fertilization Angiosperm Pollination Flower characteristic feature of Angiosperms – functions in the facilitation of – often possible to tell how plant is pollinated by – method by which a is carried to of carpel Angiosperms - great diversity of pollination vectors Pollination Vectors - pollination by insects – flowers sweet scents; blue, dark pink, yellow-red, or purple aggregated in head of many small long tubed flowers flower may have recessed parts to preclude all but long-tongued pollinators and protect ovule from herbivory – Bee; Moth; Fly; Beetle flowers all have special features Other animals Wind; Angiosperm Pollination BIOL 1030 3 Lecture 3 - Plant Diversity – mutual evolutionary influence between two species (the evolution of two species totally dependent on each other) – Each of the species involved exerts selective pressure on the other, so they evolve together – extreme example of Pollen Tube Growth & Double Fertilization Eudicot Plant Embryo Development - primary meristem that gives rise to epidermis - differentiates into the pith and cortex - primary meristem that gives rise to vascular tissue. Relationship between Pea Flower and Fruit Fruit Type fruit – 1 carpel involved – simple or compound carpel fruit – more than one carpel per flower fruit – more than one flower (rare) Fruit Function Seed – " " hidden among foliage to discourage animal consumption – contains – seeds mature, fruit " BIOL 1030 and other organic acids - fruit unpalatable " tannins and other undesirables broken down 4 Lecture 3 - Plant Diversity – broken down to sugars (sweetens fruit); fruit Seed Seed and Fruit Dispersal Four main types Wind – Air borne – plants; wings; whole plant blown across ground or ice Animal – on outside of animal carried ; hooks or spines; seed sticky when wet carried ; fruit large and fleshy or seed large – carried by mammals or birds – eaten by animal - passing through Seed and Fruit Dispersal – Plants overhanging water bodies – floating fruit or seed – discharge of fruit or seed Typical Seeds – embryonic leaves BIOL 1030 5 Lecture 3 - Plant Diversity – stem of embryo located between the cotyledons and plumule – stem of embryo located between the cotyledons and radicle – embryonic root Endosperm – thin specialized cotyledon – sheath enclosing and protecting plumule – sheath covering radicle Seed Adaptations Mature seed - dehydrated – very metabolic rate; growth and development Conditions for Breaking Dormancy – Variable – Some only need suitable environment – Some need pretreatment - specific environmental cue causes break in dormancy E.g. – Desert plants, need substantial – Plants in areas with frequent natural fires, need BIOL 1030 6 Lecture 3 - Plant Diversity – Plants from cold climates; need – Some seeds have thick seed coats – need Seed Adaptations Length of seed – Few days to decades or more – Dependent on species and environment – Most seeds are viable – Seed bank in soil in case of – e.g. Seed Germination The – first organ to emerge from germinating seed Many eudicots – hook forms in – growth pushes hook above ground – cotyledons are pulled out of ground – turn green and become Seed Germination – Use a different method for breaking ground when they germinate Corn and other grasses – The – pushes upward through soil and into air – shoot grows straight up through tube of BIOL 1030 7 Lecture 3 - Plant Diversity Feature MONOCOT EUDICOT No. cotyledons Leaf venation 1 2 parallel Vascular bundles central bundles scattered peripheral rings or arranged in circle Growth form mostly herbaceous herbaceous or __________ Mature root system FIBROUS, several one central __________ wholly adventitious primary and/or adventitious Vascular cambium Leaf petioles No. floral parts Examples: yes usually absent present multiples of _ 4's or 5's grasses (incl. cereals), palms, lilies, pineapple, cacti, sunflowers, most Angiosperm trees NOTE: no vascular cambium means limited SECONDARY GROWTH Tissue Systems Each plant organ – has all three Tissue Types Dermal Tissues protect the soft tissues of plants and control interactions with the plants' surroundings BIOL 1030 8 Lecture 3 - Plant Diversity – primary growth – secondary growth Epidermis A single layer of closely packed cells covering the younger parts of a plant Secretes a waxy layer ( ) that inhibits water loss Most epidermal cells lack chloroplasts hair-like projections – lower water loss by decreasing the flow of air over the plant surface – prevent herbivory by storing substances that are harmful to animals – increase water uptake by increasing surface area of cell – contain chloroplasts and regulate gas exchange between the inside of leaf and surrounding air Periderm Replaces epidermis in older stems and roots that undergo secondary growth Provides protection while permitting gas exchange – outer layer of periderm – produced from cork cambium – cell walls are impregnated with (a waxy material) – cells dead at maturity – lateral meristem BIOL 1030 9 Lecture 3 - Plant Diversity – blister-like breaks in the surface of the cork layer Tissue Types Ground Tissues occupy the space between dermal tissues and vascular tissues responsible for most of plant’s metabolic functions In roots, ground tissue ( ) may store sugars or starches to fuel the spring sap flow In leaves, ground tissue is the (photosythetic layer) – – – Parenchyma Structure – the cells are – each cell contains a nucleus, cytoplasm and a large central vacuole – cell surrounded by a relatively cellulose wall, very weak and flexible; no walls – at maturity Location – occur in many places in plants – stem and root cortex; stem pith (centre of stem); leaf mesophyll; flesh of fruits (e.g., ) – usually a continuous mass or in vertical or horizontal BIOL 1030 10 Lecture 3 - Plant Diversity Function – in photosynthesis, storage, secretion of materials, water movement and food transport Collenchyma Structure – typically elongate cells – primary cell wall unevenly thickened cellulosic walls – i.e. strong & thick but flexible ( ) walls – plastic nature necessary because it occurs in organs that constantly with growth – at maturity Location – occurs in bands of cells beneath the epidermis in stems and petioles – found only in young organs as organ matures becomes Function – mechanical tissue; structural support of young, actively growing plants – easily stretched during growth, can elongate Sclerenchyma Structure – various shapes – secondary wall thick, often heavily – Water and dissolved substances do not pass through (or very slowly) the wall – BIOL 1030 at maturity 11 Lecture 3 - Plant Diversity Location – found in mature organs that have Function – structural support and to plant body Types of Sclerenchyma - short cells – brittle and inflexible – groups of layers of sclereids form protective layers – e.g. – long, slender cells; pointed tip, unbranched, narrow , extremely thick secondary wall – found in places where – and is important cells continue to lengthen after rest of organs ceased to elongate great length – e.g. Tissue Types Vascular Tissues : phloem & xylem surrounded by +/- – water-conducting & supporting functions – food-conducting BIOL 1030 12 Lecture 3 - Plant Diversity Xylem Structure – complex tissue – - principal conducting cells; hollow elongated cells with thickened secondary walls - dead at maturity – Other cell types: and Function – principle water conducting tissue – produced during both primary and secondary growth Types of Tracheary elements – generally long and thin with tapered ends – contain pits in their walls through which water and nutrients can move – have imperforate (closed) end walls – found in vascular plants such as – elongated shape but not as long or thin as – have perforate (open) end walls; joined together end-to-end in long tubes called _____________________ – (wider than ) permit faster flow through the xylem Phloem Structure – complex tissue BIOL 1030 13 Lecture 3 - Plant Diversity – ; elongated cells join end-to-end to form tubes – narrower than vessel elements – are living at maturity; but lack nuclei or other organelles – Other cell types: and Function – principle – produced during both conducting tissue and growth Types of Sieve Elements – tapered; have narrow pores – accompanied by which perform sieve cells’ metabolic activities – found in – flat-ended, line up in tubes; joined at tends by sieve plates – associated with (specialized cells) perform metabolic activities – found in BIOL 1030 14