the uniqueness of bromeliads and cacti

NURUL FARIHIN BT MOHD RADZI(D20091034866)

FHATIN AMIRA BT MUSA (D20091034856)

MUNIRAH BT APANDI(D20091034850)

EZZA LIYANA BT BADRUL HISHAM(D20091034875)

NUR FARHANA BT MOHAMAD MOKHTAR (D20091034852)

WHY CACTUS SUITABLE TO GROW IN TEMPERATE REGION ?

Bromeliads And Cacti

• Both are able to survive prolonged drought and

dryness.•Easy to grow, no need to

water frequently.•Some of the species are beautiful and widely used

for landscaping

Adaptations for Cacti

• succulent plant• Size of leaves are reduced

•Developed spines, from areoles• Enlarged stems to carry out

photosynthesis and store water•Waxy coating on stems to prevent

water loss•Short growing season but long

dormancy•Able to absorb moisture through

epidermis and thorns•Shallow roots

•Undergoes Crassulacean Acid Metabolism (CAM) pathway

Cactus have some adaptations that help them grow in hot and dry climate.

That are:Spines

let out less water during transpirations than leaves.

Spines grow from specialized structures called areoles, and defend the cactus from water-

seeking animals.

StemThere are cactus plants that have

adaptations such as enlarged stems which carry out photosynthesis and store water.

These species of cacti (known as succulents) are coated with a waxy

substance coated that prevents water evaporation.

• It helps prevent water from spreading on the surface, instead forcing water down the

stem and into the roots.

Cacti have hard-walled, thick succulent stem which stores water when it rains and keeps water from evaporating. The stem is basically fleshy, green and photosynthetic, and the inside of the stem is either hollow or spongy tissue to hold water

Roots Cactus roots help to gather and preserve water in several ways.

In some cacti, shallow, extensive root systems spread laterally away from the

plant (e.g. some prickly pear roots spread 10 to 15 feet away).

In brief showers which only wet a few inches of soil, the shallow roots help the

plant maximize water intake from a large area. Cactus roots also change characteristics as the water supply

fluctuates.

After a rainfall, existing dehydrated roots become more water conductive and new

rain roots are formed to help soak up water.

In times of drought, the rain roots shrivel and fall off and the existing roots

dehydrate. The shrinkage of the existing roots creates an air gap that helps to prevent water in the roots from escaping back to the soil. A corky layer on the roots also helps to

prevent water loss.

What is the special characteristic of Bromeliads which make the farmer grow

them?

Adaptation for Bromeliads

• Trichomes in the form of scales or hairs•Tank habit : forming a tightly bound

structure with their leaves that helps to capture water and nutrients in the

absence of well-developed root system. •Crassulacean Acid Metabolism (CAM)

plant.•xerophytes

•water-conserving adaptations : a thick epidermis covered with wax, water-

storage cells that cause the leaves to appear succulent (that is thick and

fleshy)

Nidularium sp.

Nidularium sp.

Billbergia sp.

Ananas sp.

Xerophytes

The epidermis of the leaf is especially thick and tough to resist damage and desiccation.

The roots are able to resist wilting, prepared for the moment soil moisture becomes available.

thick epidermis covered with wax, water-storage cells –reserve in times of water stress

water-absorbing scales (Their thinness and large surface area make the scales ideal for rapidly absorbing water)

Undergoing Crassulacean Acid Metabolism (CAM)

C4 PLANT

What are the characteristics of

C4 plants?

Recall…

•What is phorespiration???

Crassulacean acid metabolism, also known as CAM photosynthesis, is

a Carbon Fixation pathway present in some plants. These plants fix carbon

dioxide (CO2) during the night, storing it as the four-carbon acid malate. The

CO2 is released during the day, where it is concentrated around the enzyme

RuBisCO, increasing the efficiency of photosynthesis. The CAM pathway

allows stomata to remain shut during the day, reducing evapotranspiration ;

therefore, it is especially common in plants adapted to arid conditions.

The CAM cycle is shown below...

Notice how all the reactions occur in the same cell but

at different times of the day.

The fixation step occurs at night with the guard cells open to

receive carbon dioxide during the cool night. This process is driven by use of starch to make the PEP

required for PEPcarboxylase activity. The malic acid is

transported to the vacuole and accumulates there at night. There

is a strong pH change in the vacuole at night!

The malic acid is transported back to the cytosol for the

decarboxylation reaction. This floods the Calvin cycle with

carbon dioxide while the guard cells are closed. The energy of course comes from the light reactions and accumulated

starch is used the next night for another round of carbon fixation.

These adaptations enable the plant to thrive in conditions of :

•High daytime temperatures•Intense sunlight

•Low soil moisture“This is because they close off their pores to conserve water and work on producing energy by using the C3 process and the C4 compound

they created during the night.So they can survive when the

drought season come. But plant that undergo this pathway have

slower growing rate“

THANK YOU…The End