Plant StructuresPlant Structures

AP BiologyUnit 5

Extreme Plants!

• Deepest Root: – fig tree in South Africa – roots that extend 120 m (393.7 ft)

into the ground

• Tallest Tree: – Sequoia tree in the Humboldt

Redlands State Park (CA)– 370 ft (in 2004)

Images taken without permission from http://www.gagfactory.com/photos/usa1999/part06/moreton_bay_fig_tree.jpg and http://www.nps.gov/archive/seki/shrm_pic.htm

Extreme Plants!

• Largest leaf: – raffia palm and Amazonian

bamboo – can have leaves up to 65 ft in

length.– Alocasia Macrorrhiza has the

longest undivided leaf– 9 feet long, 6 feet wide

Images taken without permission from http://images.google.com/imgres?imgurl=http://thelongestlistofthelongeststuffatthelongestdomainnameatlonglast.com/images3/leaf.JPG&imgrefurl=http://thelongestlistofthelongeststuffatthelongestdomainnameatlonglast.com/long330.html&h=259&w=195&sz=12&hl=en&start=1&tbnid=1oWtKUiri7q7nM:&tbnh=112&tbnw=84&prev=/images%3Fq%3D%2522Amazonian%2Bbamboo%2522%26svnum%3D10%26hl%3Den%26lr%3D and http://www.raffiaonline.com/imgs/about-page/raffia-palm.jpg

Extreme Plants!

• Slowest growing tree: – A white cedar in Canada – has only grown to a height

of 4 inches and 0.6 oz over the course of 155 years.

• Fastest Growing Plant: – Some species of bamboo – grow up to 3 ft in a day

Images taken without permission from http://www.ponnitai.com/database/thuja/occidentalis/europe_gold2.jpg andhttp://www.landoftheanxiousdog.com/images/bamboo.jpg

Roots

• The function of roots in a plant is to – Anchor plant – Absorb water and minerals – Store organic nutrients (starch)

Types of Roots

• Types of roots include: – Taproot – Fibrous Root – Adventitious Root

Taproot

• One main root

• Lateral roots (smaller side roots) come off of main root

• Good for storage of organic nutrients (starch)

• Ex. carrots, turnips

Img Src: http://collections.ic.gc.ca/gardens/New%20Bio%20Web%20Pix/OPTIMIZED%20BIO%20PLANT%20PARTS/3%20root%20systems.jpg

Fibrous Roots

• Lots of smaller roots (no main root)

• Large surface area (good for absorbing water and nutrients)

• Clings to soil well– prevents erosion

• Ex. grass

Img Src: http://collections.ic.gc.ca/gardens/New%20Bio%20Web%20Pix/OPTIMIZED%20BIO%20PLANT%20PARTS/3%20root%20systems.jpg

Adventitious Root

• Roots that grow out of plant parts above ground (like the stem or the leaves)

• Allows plants to re-establish selves even after stem has been cut off, lends support

• Ex. Corn, banyan trees, some palms use them for additional support

Img Src: http://collections.ic.gc.ca/gardens/New%20Bio%20Web%20Pix/OPTIMIZED%20BIO%20PLANT%20PARTS/3%20root%20systems.jpg

Root hairs

• Located just after the root tips

• Tiny projections that increase the surface area on the root for water and mineral absorption

Question…

• What kind of roots would a landscape architect want to have in plants (s)he puts on a steep hillside to prevent a landslide from occurring

• Fibrous roots– holds the soil better, so there won’t be erosion.

Parts of a Leaf

• A leaf consists of – Blade– Petiole

This whole thing is a leaf!

Img Src: http://www.yourdictionary.com/images/ahd/jpg/A4leaf.jpg

Parts of a Leaf

• The leaf is also where most photosynthesis takes place

• Leaves can also be modified for support, reproduction, protection and storage. – Ex. Spines on a cactus, flower petals

Parts of a leaf

Palisade Mesophyll Cells

Bundle Sheath CellsXylem

Phloem

Epidermis

EpidermisSpongy Mesophyll Cells

Guard CellsStoma

Cuticle

Cuticle

Vein

Question…

• In which cells would the most photosynthesis take place– palisade or spongy mesophyll?

• Palisade mesophyll– because they are at the top, they have the most access to sunlight.

Plant Tissues• 3 types• Dermal Tissue

– Outer covering of the plant– Includes epidermis, cuticle,

guard cells

• Vascular Tissue– All transport systems (xylem and

phloem)

• Ground Tissue– Everything else in the plant– Storage, support, photosynthesis

Plant Cell Organelles

• Chloroplast– Site of photosynthesis

• Mitochondria– Site of cellular respiration

• Tonoplast– For water storage

• Leucoplast– For starch storage

Plant Cells- Parenchyma

• Thin walls• Most abundant cells in

young plants• Usually photosynthetic

cells• Other

nonphotosynthetic cells are for starch or lipid storage

Plant Cells- Collenchyma• Supporting cells– when

living• Thicker walls than

parenchyma• Flexible and elongated• Ex. Collenchyma cells in the

petioles allow them to sway in the wind without breaking

• Ex. “Strings” in celery are also made up of collenchyma

Plant Cells- Sclerenchyma

• Supporting cells– when dead

• Have thickened walls

• Ex. Cells in bark of trees, cells that make up the xylem

Plant Cells- Transport

• Water-conducting cells (Make up the xylem)

• Sugar-conducting cells (Make up the Phloem)