Page 160 - Ultimate Visual Dictionary (DK)

PLANTS

Wetland plants

WETLAND PLANTS GROW SUBMERGED IN WATER, either partially (e.g., water hyacinth) or completely (e.g.,
pond weeds), and show various adaptations to this habitat. Typically, there are numerous air spaces inside the
stems, leaves, and roots; these aid gas exchange and buoyancy. Submerged parts generally have no cuticle
(waterproof covering), enabling the plants to absorb minerals and gases directly from the water; in addition,
being supported by the water, they need little of the supportive tissue found in land plants. Stomata, the gas
exchange pores, are absent from plants WATER HYACINTH
Abaxial (lower) Adaxial (upper) surface
that are completely submerged; in surface of of lamina (blade) (Eichhornia crassipes)
partially submerged plants with lamina (blade)
floating leaves (e.g., water lilies),
Inflated petiole
stomata are found on the upper (leaf stalk)
leaf surfaces, where they cannot provides buoyancy
be flooded. Isthmus (narrow
Leaf connecting
region)
WATER FERN Dorsal lobe
(Azolla sp.) of leaf Orbicular
lamina
(blade)

Leaf with tiny
Stem hairs to prevent Rhizome
waterlogging
Adventitious
root

Dense, fibrous
root system
Adventitious
root
Lateral branch of
adventitious root
Orbicular
lamina
(blade)
Vein
Endodermis
Isthmus (inner layer
(narrow of cortex) CANADIAN POND WEED
connecting (Elodea canadensis)
region) Lacuna Phloem Vascular Internode
(air space) Xylem tissue
Epidermis
(outer layer
of cells) Node
Inflated
petiole Node
Lacuna
(leaf stalk)
(air space)
Cortex Stem
(layer between
Epidermis
Leaf base (outer layer epidermis and
of cells) vascular tissue)
Adventitious
LAMINA AND SECTION THROUGH INFLATED MICROGRAPH OF CROSS-SECTION root
PETIOLE OF WATER HYACINTH THROUGH ROOT OF WATER HYACINTH
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