1. • Plants: 99 % of all living matters
a. Submerged on lake bottoms
b. Exposed to wind-swept mountain tops
c. Hidden within polar rocks
d. Perched on branches in rainforests
Can be:
a. Microscopic
b. Sequoias (upto 300 meters)
4. Hydrophytes/Macrophytes/Aquatic Plants
• ”Plants adapted to living in aquatic environments
(saltwater or freshwater)”
• Monocots or dicots; vascular or non vascular
Morphological classes
• Amphiphytes: plants that are adapted to live either
submerged or on land.
• Elodeids: stem plants that complete their entire life cycle
submerged, or with only their flowers above the waterline.
• Isoetids: rosette plants that complete their entire life cycle
submerged.
• Helophytes: plants rooted in the bottom, but with leaves
above the waterline.
• Nymphaeids: plants rooted in the bottom, but with leaves
floating on the water surface.
• Pleuston: vascular plants that float freely in the water.
5. • Adaptations
• 1. Thin cuticle.
• 2. Stomata open most of time (as water is abundant).
• 3. Increased # of stomata.
• 4. Plants in water have less structure (water pressure supports
them).
• 5. Large flat leaves on surface plants for flotation.
• 6. Air sacs (aerenchyma) for flotation/gaseous exchange.
• 7. Reduction in roots (H2O can diffuse directly into leaves).
• 8. Roots of water plants are feathery to hold up plant.
• 9. Roots modified to pick up oxygen.
6. Cactus
• “Cactus – a member of family cactaceae within order
caryophyllales” and “a plant is a succulent if it stores water
in juicy leaves or stems in order to survive dry spells” or “a
plant possessing at least one succulent tissue”
• About 90 % mass is water
• Derived from Greek word “kaktos”, a spiny plant with
uncertain identity
• Cactaceae – largest family, comprising about 2000 plants
including endangered
• Of great ecological, medicinal and economic importance
• Most of them exist in the areas facing drought. The main
centres of diversity occur within Americas, Africa and
Srilanka
• Almost all cacti are succulents from tree to small plants
• They are of different sizes and shapes
7.
8.
9. Adaptations
• Spines in the form of leaves
• Spines help trapping air and making plant surface moist,
protection against herbivores, provide some shade and lower
temperature, reduce water loss, moisture captured inside is
condensed into drops which finally drop into soil.
• Water storage for drought season in stem, stem shapes vary
which helps in reducing surface area to volume ratio,
photosynthesize, contains dense cuticle and waxy layer thus
reducing transpiration
• They form immediate root after the rain falls
• CAM photosynthesis
• Stomata open at night
Editor's Notes
Living stones/cacti
Spherical in shape – maximizing volume with min surface area
Cacti show a wide variety of growth habits, which are difficult to divide into clear, simple categories. They can be tree-like (arborescent), meaning they typically have a single more-or-less woody trunk topped by several to many branches.
They may be shrubby, columnar, globular, forest climber, epiphytes etc.
Areoles are highly specialized and very condensed shoots or branches. They typically appear as woolly or hairy areas on the stems from which spines emerge. They are of different shapes, color and sizes.
Spines are different in number, size, color, shape and used for identification. E.g. hooked (mammilaria genus)
Fibrous root system.
