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SUPPORT IN AQUATIC PLANTS
SUBMERGED PLANTSHydrilla sp.
Curly-Leafed Pondweed
American Pondweed
• Thin, narrow and flexible leaves
• There are air sacs within the leaves and stems which keep the plants afloat close to the surface to obtain maximum sunlight• Water provides buoyancy (water buoyancy) which
support these plants
Provide little resistance to water flow
This means submerged plants can be tugged at and pulled by water currents with little damage
If these plants are removed from water, they become limp and floppy
FLOATING PLANTSWater Hyacinth
Bladderwort
Duckweed
Water Lettuce
• Broad leaves that are firm but flexible enough to resist being torn by wave action• Aerenchyma tissues in the stems and leaves
Spongy tissues with large air spaces between the cells
Provide buoyancy so that plants can float on the surface of the water
TERRESTRIAL PLANTSNON WOODY PLANTS WOODY PLANTS
NON-WOODY PLANTS• Herbaceous plantsi. Support is provided by turgidity of the parenchyma and
collenchyma cellsii. The thickening of the cell walls with cellulose and pectin in the
parenchyma cells provide additional mechanical strength.iii. Example:
Balsam Spinach Maize
• Climbersi. Have tendrils which grow from the base of leaf stalks. Ex: Morning glory
ii. Have thorns to hook on to a nearby support.Ex: Rose
2.3 SUPPORT SYSTEMS IN PLANTS
• COLLENCHYMA • SCHLERENCHYMA
SUPPORT IN WOODY PLANTS
• XYLEM
2.3 SUPPORT SYSTEMS IN PLANTS• Woody plants
– Support provided through tissue modification– Xylem tissue
• Consists of xylem vessel and tracheids• Strenghtened by lignin during development (primary
growth)• Lignin – tough, inelastic and not permeable to water• Store starch, sugars and water• It become turgid – give support• Lignin allows the formation of different types of
vessels (primary xylem, primary growth)• As plants grow, they undergo secondary growth and
form secondary xylem (wood)
2.3 SUPPORT SYSTEMS IN PLANTS• Woody plants
– Collenchyma tissues• Thickened with cellulose and pectin
– Schlerenchyma tissues• Thickened with lignin• Support non-growing parts of plants