xerophytic & hydrophytic plants

• What are adaptations of xerophytes that allow them to live in dry conditions?

  small/rolled leaves -

  densely packed mesophyll -

  thick waxy cuticle -

  stomata often closed -

  hairs to trap moist air -
• What are adaptations of hydrophytes that allow them to live in wet conditions?

  thin / absent waxy cuticle

  stomata often open

  wide, flat leaves

  air spaces for buoyancy
• What are xerophytes?

  plants that are adapted to dry and arid conditions

  xerophytes have physiological and structural (xeromorphic) adaptations to maximise water conservation
• How are the walls of the xylem vessels in the stems of a hydrophyte different to the xylem vessels stems of a xerophyte?

  hydrophyte has no/less lignin than xerophytes

  xerophyte has more lignified walls

  hydrophyte has thinner walls than xerophytes, xerophyte has thicker walls
• what is the advantage of plant that grow underwater having no waxy cuticle?

  water loss is not a problem

  wax production wastes energy
• what is the advantage of plants that grow underwater having stem tissue that contains air spaces?

  buoyancy: allows it to float

  increases gas exchange
• what is the advantage of plants that grow underwater having a thin, flexible stem?

  less support is needed

  can move more in the water without breaking
• what are halophytes?


  plants that have the ability to live in soils with a very low water potential

  in the UK these plants form part of salt marsh communities
• how do the roots of halophytes absorb water by osmosis from the soil of the salt marsh?

  there is a lower water potential inside root hair cells, thus sets up a steep water potential gradient

  ions are actively transported into the root hair cells