Focus Question: Plant Structure and Growth IB Topic: 9.1 Text:  Chapters Web Site: 35A/B

Monocots vs. Dicots Monocots-  One cotyledon (seed leaf), when sprouting.  Floral organs in multiples of 3’s  Vascular bundles are scattered  Long tapering leaves with parallel venation  Roots- unbranched  Ex. Grasses, rice, corn, lily Dicots-  two cotyledons (seed leaves) when sprouting.  Floral organs in multiples of 4 or 5  Vascular bundles are arranged in a circle  Broad to narrow leaves with net-like venation  Roots- branched  ex: aspen tree, daisy, rose

Evolution of Plants… Algae- not a plant, but a protist Algae  monocots  dicots

IB focuses on Dicots…  Bryophytes  Filicinophytes  Coniferophytes  Angiospermophytes

Draw and locate the following on a local plant: Roots, stem, leaves, axillary buds, terminal buds

Vacular Tissues of a Plant: Xylem: water conducting vessels  moves water and dissolved minerals upward from the roots  Vessels are large and dead Originally live cell columns. As cells died left the vessels behind. Phloem: food conducting cells  transports the products of photosynthesis (sugars) from leaves or storage tissue to other parts of the plant.  Living tissues  Made up of companion cells that are involved with the production of ATP in plants

Dicot Stem Structure Xylem Phloem

Dicot Root Structure “X” in the middle (xylem) Phloem surrounding it

Dicot Leaf Structure

Structure and Function of a Leaf Functions should include  absorption of light  gas exchange  support water conservation  transport of water and product of photosynthesis

Structure and Function of a Leaf TissueStructureFunction Upper cuticleNOT tissue- Waxy outer layer Reduces water loss Upper epidermisSingle layer, no chloroplasts, transparent Reduce water loss, pervents gas exchange, light passes, barrier against infection Palisade layerLong cells, lots of chloroplasts, near top of leaf- receives most light Photosynthesis Spongy layerIrregular shaped cells with air space, has some chloroplasts Rapid gas exchange, photosynthesis Lower epidermisStomataGas exchange, barrier against infection Lower cuticleNOT tissue- waxy layerReduced water loss

Modified roots, stems, and leaves Bulb- grows underground, plants can re-grow after being dormant- monocots only- ex- onion Stem Tubers- stems modified for food storage, ex- potatoes Storage roots- roots that store water or food, ex- carrots Tendril- specialized stem or leaf which attaches the plant to something, ex- sweet pea

Apical vs. lateral meristems Apical  Primary growth  Primary concern is making plant longer  Both woody and non- woody plants have this primary growth (annuals) Lateral  Secondary growth  Primary concern is getting wider  Mainly occurs in trees, shrubs, and herbaceous dicotyledons  Thickening of roots and stems (2 lateral meristems) Vascular cambium Within vascular bundles Cork cambium External to the vascular bundles- bark

Auxin (plant hormones) in phototropism (plant growth in response to direction of light) Mainly synthesized in the apical meristem Promotes primary growth Other plant responses:  Apical dominance High concentrations result in lack of lateral branches near apex  Growth responses to light and gravity  Root development  Fruit growth development