Post on 06-May-2015
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WETLAND PLANTS 24th Annual Environmental Permitting Summer School at Marco Island
Presented by Edward Murawski
• Wetland Plant Definition
• Growth Forms
• Representative Plant Groups
• Wetland Plant Morphology and Physiology
• Functions
WETLAND PLANTS DISCUSSION OVERVIEW
Wetland plants are those species that normally grow within areas of standing water or where the soils are saturated within the root zone long enough for anaerobic soil conditions to develop. Wetland plants have morphological and physiological characteristics that enable them to grow in these areas.
Wetland Plant Definition
Wetland plants are often referred to as Hydrophytes
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4. Floating
Growth Forms
3. Submerged
2. Floating-leaved
1. Emergent
Four Main Growth Forms
Phelps, 1995
Growth Forms – Emergent
Emergent plants are those species rooted in saturated soils or below standing water but have their stems, leaves and reproductive parts above the water level.
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2. Floating-leaved
Growth Forms
Phelps, 1995
Growth Forms – Floating-leaved
Floating-leaved plants are species that root in the soil and have leaves that float on the surface of the water.
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Growth Forms
3. Submerged
Phelps, 1995
Growth Forms – Submerged
Submerged plants are rooted in the soils and have their stems and leaves under water. Flowers and other reproductive parts are found both above and below the water column.
Growth Forms - Floating
Floating plants are species that do not root in the soil. These species float on the water column.
Bryophytes – Mosses
Wetland plants are represented by all major plant groups.
Pteridophytes – Ferns and Allies
Gymnosperms – Cypress and Conifers
Angiosperms – Flowering plants
Representative Plant Groups
Bryophytes – Mosses
Herbaceous Species
Representative Plant Groups
sphagnum moss (Sphagnum spp.)
Pteridophytes – Ferns and Allies
Herbaceous species
netted chain fern (Woodwardia areolata)
Virginia chain fern (Woodwardia virginiana),
royal fern (Osmunda regalis) and
cinnamon fern (Osumunda cinnamomea)
Representative Plant Groups
Gymnosperms – Cypress and Conifers Woody Trees
bald cypress (Taxodium distichum)
pond pine (Pinus serotina)
Representative Plant Groups
Angiosperms – Flowering plants
Herbaceous and Woody Species (herbs, shrubs and trees)
duck potato (Sagitaria spp.)
loblolly bay tree (Gordonia lasianthus)
blue flag iris (Iris hexagona)
Representative Plant Groups
Wetland Plant Morphology and Physiology
The wetland environment subjects wetland plants to conditions that upland plants do not have the tools to cope with.
The most critical condition is anaerobic soil conditions
(low oxygen levels).
Anaerobic Soil Conditions
Problem – Oxygen deprivation
– When soils are saturated, the air in the void spaces is replaced with water.
– Any oxygen left is used by bacteria and other microorganisms at a rate that exceeds replenishment via diffusion.
– Therefore, saturation results in oxygen deprived soils, which is called anoxia.
Wetland Plant Morphology and Physiology
Anaerobic Soil Conditions
Problem – Oxygen deprivation
– Plants require carbon dioxide for photosynthesis, but plants need oxygen too!
– Just like animal cells, plant cells need oxygen for normal cell functions, including cell division and nutrient absorption.
– These cell functions require energy. Energy is released from biochemical reactions, which is referred to as cellular respiration. Oxygen is required for cellular respiration.
Wetland Plant Morphology and Physiology
Anaerobic Soil Conditions
Problem – Oxygen deprivation
– In the absence of oxygen, plant cells conduct anaerobic respiration.
– Anaerobic respiration is not as efficient as aerobic respiration, but will provide the energy needed until the plant roots are exposed to atmospheric oxygen, either by drainage of water or by development of morphological structures to aid in obtaining oxygen.
Wetland Plant Morphology and Physiology
Anaerobic Soil Conditions Problem – Oxygen deprivation
Solutions
• Aerenchyma• Specialized root structures• Hypertrophy• Underwater growth techniques• Timing
Plants have several morphological and physiological characteristics that enable the root cells to obtain oxygen for cellular respiration, the release of energy required for cell function. These include:
Wetland Plant Morphology and Physiology
Oxygen deprivation Solution
Aerenchyma• Aerenchyma are air spaces located
throughout the plant, including the roots. These spaces allow for gas exchange between the aerial parts of the plant and the roots. This provides a connection between the submerged roots and the aerial portion of the plant where oxygen is prevalent.
• Aerenchyma also act as a floatation device to stabilize some species in the water column.
Wetland Plant Morphology and Physiology
PicsDigger, 2010
Oxygen Deprivation Solution
Specialized Root Structures
Adventious Roots
– Adventious roots are roots that grow from the base of a plants stem above the soil or water surface. These roots grow into the surrounding soil or within the air.
– Adventious roots have the advantage of being exposed to atmospheric oxygen.
Wetland Plant Morphology and Physiology
Oxygen Deprivation Solution
Specialized Root Structures
Prop Roots • Prop roots provide stability from wind and tide and aid in oxygen uptake.
Wetland Plant Morphology and Physiology
Oxygen Deprivation Solution
Lenticels
Lenticels are small, corky pores or narrow lines on the surface of the stems of woody plants that allow the interchange of gases between the interior tissue and the surrounding air.
Wetland Plant Morphology and Physiology
Oxygen Deprivation Solution Specialized Root Structures
Pneumatophores• Pneumatophores are roots that grow upward above the soil surface. • Typical Species
- Mangrove species – Aid in uptake of oxygen through lenticels.
- Cypress species – Aid in gas exchange.
Often referred to as “Cypress knees”.
black mangrove (Avicennia germinans) bald cypress (Taxodium distichum)
Oxygen Deprivation Solution Specialized Root Structures Shallow Rooting
• Some species grow their roots close to the surface of the soil.• Shallow rooting enables the roots to maximize their proximity to oxygen
in the atmosphere or water column.
Hypertrophy• Hypertrophy is when the base of the stem of some plant species swell
when subjected to inundation of water. • Formation of aerenchyma is the cause of the swelling. • The swelling assists the plant roots in gaining oxygen as well as with
the stability of the plant in the wetland soils.
Wetland Plant Morphology and Physiology
OTHER SPECIALIZED STRUCTURES
– Some wetland plant species have large rhizomes.
– Rhizomes are thick fleshy underground stems.
– The rhizomes aid in anaerobic respiration.
– Anaerobic respiration requires larger quantities of glucose than aerobic respiration.
– The rhizomes provide large quantities of carbohydrates to fuel anaerobic respiration until these plants can emerge from the water.
Underwater Growth Techniques• Some species have an ability to grow shoots from below the water
surface very quickly, enabling them to reach the surface of the water.
• This very quick growth rate also aids some deep water species to reach sunlight and oxygen quickly.
• Submerged vegetation tends to be thin or dissected, which provides greater leaf surface to volume ratio, thus increasing the exposure to both light and oxygenated water.
Wetland Plant Morphology and Physiology
TimingSome wetland plants focus their growth and reproductive activities during periods of dry conditions.
Wetland Plant Morphology and Physiology
Water quality treatment
Nutrient assimilation
Functions
What do wetland plants do?
Erosion control
Functions
What do wetland plants do?
Support to wildlife
– Cover
– Food
– Nesting and denning sites
FunctionsWhat do wetland plants do?
Wetland plants are those species which normally grow within areas that have standing water or where the soils are saturated within the root zone long enough for anaerobic soils conditions to develop. Wetland plants have morphological and physiological characteristics which enable them to grow in these areas.
Multiple Growth Forms are represented in all the major plant groups.
Wetland Plants provide multiple functions including:
• Water quality treatment• Erosion Control • Wildlife Support
Summary
Presented by Edward Murawski
WETLAND PLANTS