Hydrophyte

• Water-logging is problem of all hydrophytes as air spaces need to be full of air, not water; as it will help the plants float on the surface so they can get more light for photosynthesis
• Thin to no waxy cuticle and those with floating leaves have their stomata on the upper surface so in contact with the air, many are always open
• No supporting structures; water supports leaves, some hydrophytes have air spaces to enables floating (very large and thin) leaves on the surface
• Smaller roots as less uptake needed, elongated petioles (leaf stalks), aerial flowers, poorly developed xylem, little to no lignin in vascular bundles and few sclereids or fibres
• Arenchyma: Spongy tissue in roots, leaves and stems, filled with O_2 from photosynthesis; it helps to keep plant buoyant and forms low-resistant oxygen pathway to diffuse to tissue below water
• Pneumatophores: Roots become water-logged, air is in short supply so they develop special aerial roots; these have lenticels (raised pores) which allow gases into the roots