Lecture 8 Cornales, Ericales, and peatland ecosystems Flashcards
What are leaf/stem characteristics of Cornaceae?
- Woody plants
- Simple opposite or whorled leaves
(except Cornus alternifolia) - arcuate venation
What order are Violaceae, Salicaea, Euphorbiaceae, Passifloraceae, Hypericaceae, Rhizophoraceae part of?
Malpighiales
What are some floral characteristics of Cornaceae (dogwood) family?
- Flowers perfect
- 4-merous (4 sepals, petals, stamens)
- inferior ovaries
- 2 fused carpels
- single stigma
- epigynous nectar disk
- inflorescence a compound cyme, sometimes subtended by petaloid bracts
What kind of fruit does the Cornaceae family produce?
Drupes (red, white or blue)
Where is the Cornus canadensis found?
Common in boreal forests understories across Canada
Occasionally in temperature forests
Can also grow in open habitats with low disturbance, such as peatlands
Where is the Ericaceae (heath) family found?
Common in tropical mountain habitats, eastern North America, southern Africa, eastern Asia and Australia
Usually shrubs found in full sun and on acid soils
Because they form associations with ericoid mycorrhizae, they are more efficient at acquiring mineral nutrients in acidic environments than other mycorrhizal fungi groups
What are characteristics of Ericaceae family?
- shrubs/subshrubs or small trees
- alternate, opposite, or whorled leaves
OR - herbaceous, mycoparasitic, and lacking chlorophyll
- leaves often with xeromoprhic features
- anthers (8-10 in number) opening by two pores
- bisexual
- radial or slightly bilateral symmetry
- calyx 4-5 sepals
- corolla 4-5 fused or free petals
- usually bell-shaped petals
- axile placentation
- fruit capsule, berries, or drupes
What is a peatland?
Wetland underlain by partially decomposed or undecomposed OM, usually derived, at least in part, from Sphagnum mosses to a depth of at least 12 inches
- defined by accumulation of peat
Generally found in cool, wet climates, with relatively short growing seasons–but can also occur in the tropics
Water-saturated anaerobic conditions
What is a bog?
Ombrotrophic: receives its water only from rain or snow (fed from the clouds)
What is a fen?
Minerotrophic: receives water from precipitation and from ground water and elsewhere (fed from minerals in the earth)
What is the role of sphagnum in peatlands?
Reduces the pH of the bog water and generally limits decay of organic matter from the action of microbes (creates the habitat of peatlands)
What are the mechanisms behind sphagnum’s role in peatlands?
Sphagnum holds large quantities of water, which leads to anoxic environments–low O2 limits plants in low areas and more
Produces sites of cation exchange on surface, will give off H+ ions but absorb Ca 2+ and other base cations
Produce phenolic compounds, which bind nitrogen in the dead bodies of vascular plants, animals, etc.
Produce anti-microbial compounds
–> result: peat accumulation–some species form mounds, some are in flat, wet depressions and other plant growth very limited leading to open, moist habitats ideal for sphagnum
What are some plant adaptations in peatlands?
Deep roots that can access the mineral soil to acquire some of its nutrients
Thick, waxy evergreen leaves
Carnivory as another way to get limited nutrients
Why do leaves in peatlands look similar to those adapted to dry conditions?
Nutrients are difficult to get, so plants retain them longer. To maintain leaves over winter requires increased mechanical strength and ways to protect them from herbivores
Why is carnivory common in peatlands? How does it work?
To access nutrients
Carnivorous plants have glandular hairs that trap and digest small insects to gain nitrogen and phosphorous
What are examples of trees found in peatlands?
Picea mariana
Larix laricina
Thuja occidentalis
Alnus incana
Acer rubrum
Betula populifolia
What other types of plants are found peatlands?
Ericaceous shrubs
Orchids
Nymphaeaceae plants (in the shallow, open water habitats of peatlands)
What two families have we seen in the Malphigales family?
Violaceae and Salicaceae
What are stem/leaf characteristics of Viola genus?
- herbaceous plants
- alternate or basal leaves
- small plants
What are floral characteristics of Viola genus?
- zygomorphic, usually with a spurred petal
- 5 stamens with very short filaments
- nectaries on two project into back of flower (so that pollinators would have to get past other flower parts to get to the pollen)
- superior ovary of 3 fused carpels
- many ovules
- parietal placentation
What type of fruit does Viola genus produce?
Capsule
How are Viola flowers pollinated?
May have both flowers that open and are insect pollinated (chasmogamous) or that remain closed and are self-pollinated
What does chasmogamous mean?
Opens up for cross-pollination (by insects)
What does cleistogamous mean?
Self-pollinated
Not opening at maturity and selfing
