the uniqueness of bromeliads and cacti
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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