XylemAnd

Phloem

Vascular tissue evolved as an adaptation to life on land. It consists of a series of

elements that form tubes throughout the plant.

Both are vascular tissue (tubes) Both are found in roots, leaves and stems. Both transport materials needed by plants

• Composed of dead cells• Cells are made of thick

cell walls• Found in wood• Carries water and

nutrients• Transports materials up

the stem…capillary action(like a straw)

• Helps support the stem

Phloem• Composed of living cells• Cells don’t have

thick cell walls• Found in bark• Carries food

(sugar-sap)• Transports materials up

and down the stem(like an elevator)

• Does not support the stem

Xylem

LeavesA leaf is an above-ground plant organ

specialized for the process of photosynthesis and transpiration.

A leaf is typically flat and thin. As an evolutionary trait, the flatness of leaves works

to expose the chloroplast to more light and to increase the absorption of carbon dioxide at the expense of

water loss.

Stomata – pores where gas exchange takes place.

Guard cells – open and close the stomata to facilitate the exchange of gas and water vapor.

Veins – are the xylem and phloem tubes.

Cuticle – thin waxy covering of plants that prevents water loss.

is the evaporation of water in plants through the stomata.

• Transpiration takes place mainly in the underside of leaves but also occurs through roots and stems.

Water travels up through xylem

tubes

Water enters the roots

Water evaporate

s through stomata

in leaves

Water lost by transpiration.

Capillaryaction

Water absorbed by root hairs.

Turgor Pressure

Transpiration is necessary… • for distributing water,

nutrients, CO2 and O2 throughout the plant.

• the ingredients are essential for photosynthesis and respiration.

• to be able to take up carbon dioxide from the atmosphere

• to maintain plant temperature• to maintain the water cycle

(10 percent of the moisture found in the atmosphere is released by plants through transpiration)

The following parts of a leaf will help in identifying plants.

saw-toothed

smooth

double saw-toothed

lobed

parallel

palmate

pinnate

opposite alternate

simplepalmatelycompound pinnately

compound

v-shapedrounded

flat heartuneven

Dichotomous means “divided into two parts”.

Di = 2

In a dichotomous key two questions are offered; one will direct you to the answer and the other will direct you to a set of two more

questions. By following the key and making the correct choices, you should be able to identify

the name of an unknown organism.For example…we could construct a key using the

following stationary supplies taken from a student's pencil

case.

1. a. long, tubular objects------------go to #2

1. b. short, non-tubular objects-----go to #4

2. a. constructed from plastic--------go to #2

2. b. constructed from wood---------go to #4