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Plants: 99 % of all living mattersSubmerged on lake
bottomsExposed to wind-swept mountain topsHidden within polar
rocksPerched on branches in rainforests
Can be:MicroscopicSequoias (upto 300 meters)
Plant types and their relationship to water
depthsHydrophytes
Hydrophytes/Macrophytes/Aquatic PlantsPlants adapted to living
inaquatic environments (saltwaterorfreshwater)Monocots or dicots;
vascular or non vascularMorphological classesAmphiphytes: 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.
Adaptations1. 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.
Cactus
Cactus a member of family cactaceae within order caryophyllales
and a plantis asucculentif it stores water in juicy leaves or stems
in order to survive dry spells or a plant possessing at least one
succulent tissueAbout 90 % mass is waterDerived from Greek word
kaktos, a spiny plant with uncertain identityCactaceae largest
family, comprising about 2000 plants including endangeredOf great
ecological, medicinal and economic importanceMost of them exist in
the areas facing drought. The main centres of diversity occur
within Americas, Africa and SrilankaAlmost all cacti are succulents
from tree to small plantsThey are of different sizes and
shapesLiving stones/cactiSpherical in shape maximizing volume with
min surface area
Cacti show a wide variety of growthhabits, which are difficult
to divide into clear, simple categories. They can be tree-like
(arborescent), meaning they typically have a single more-or-less
woodytrunktopped by several to manybranches.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.6
AdaptationsSpines in the form of leavesSpines 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 transpirationThey form immediate root after the rain
fallsCAM photosynthesisStomata open at night
