FOR 232 Exam 2

vegetative reproduction (asexual)

• reproduction w/o fertilization

• identical genetics

sexual reproduction

• monoecious and dioecious plants

• major fruit types:

  • fleshy/berry-like

  • dry/nut-like

    • dehiscent: opening along slits or valves

    • indehiscent: seeds remain in fruit after fruit has been shed from parent plant

seed dormancy and germination types:

• no dormancy

• hard seed coat

• immature embryo

• physiological dormancy

no dormancy

• small seeds, released in winter or spring (moist seedbed, great for germination + growth)

• some pioneer trees (aspen, red/silver maple, river birch)

• white oaks (subgenus) acorns germinate in fall, primary tap-root growth

hard seed coat

• requires scarification

• fabaceae (legume) family

• scarification methods:

  • animal digestive tracks

  • soil microorganisms

  • human (anything that scratches seed coat)

immature embryo

• delays germination

• “over-winter” rather than germinate in the fall

• ex: ginkgo, eastern redcedar

physiological dormancy

• requires stratification

• controlled by hormone abscisic acid (keeps things dormant)

• released by hormone gibberellic acid

• red oaks (subgenus), most conifers

seed dissemination

• wind

• mechanical/physical

• animal

root collar

new stem forms at the junction of the trunk and root

roots/root suckers

arise from roots

rhizome

underground stem that gives rise to new stems

runner

creeper stem that goes along soil surface and takes root

stolon

arching stem that takes root in soil

layering

lower branches take root

tipping

tree fall and branched become erect stems

fragmentation

stem pieces broken off tree root on stream bank

co-evolution benefits for pollination

• floral nectaries (glands on cherries)

• closed carpel and inferior ovary - protection from seed predators

• bisexual flowers - more efficient pollination

beetle pollinated flowers

Magnolia sp., Cornus sp., Rosa sp.

bee pollinated flowers

Malus sp., Robinia sp., Amelanchier sp., Tilia sp.

wind pollinated flowers

Ulmus sp., Acer sp., Betula sp., Populus sp.

Moth and butterfly pollinated flowers

yucca moths and joshua trees

fly pollinated flowers

witch hazel, jack-in-the-pulpit

challenge that plants face related to seed dispersal

attraction, timing, escape

specialization

highly nutritious fruits, specialized animals

generalization

less nutritious, opportunists

fruit/seed physical deterrents

thorns, spikey seeds

chemical deterrents

tannins in red oak acorns

plant defense against pests

• complete tolerance (damage leads to response)

• complete immunity (using energy to not get eaten - physical and chemical defense)

• “immune” plants susceptible under outbreaks or stress

• main defense types: structural, protein-based, chemical

• depends on:

  • types of tissue attacked

  • timing of attack

  • size of unit attacking

• least damaging: leaf feeders, twig gall-formers

• intermediate: root feeders, woodborers

• most damaging: bark beetles on roots and main stem

gall

abnormal growth on a plant (reaction to the damage)

• caused by:

  • insects

  • mites (maple bladder __, maple spindle __)

  • fungi (black knot)

  • bacteria (crown __ on roots)

conifer defenses against pests

create oleoresins

hardwood defenses against pests

juglone (most toxic), tannins, and rapid leaf flushing

tree relationships with mycirrhizal fungi

plants synthesize sugars and carbon → fungi take this and give micronutrients to trees

-allows for healthier trees (pests attack weakened trees)

plant defenses against mammals

armed stems (thorns, prickles, spines)

chemicals in stems and leaves

suckering/propagations

What is the relationship between plant health and insect herbivory?

insects benefit, plants negatively impacted under drought conditions

Dry (oak-pine)

• Northern pin oak (Q. ellipsoidalis)
• Black oak (Q. velutina)
• Jack pine (P. banksiana)

Dry-mesic to mesic (oak forests)

• Northern red oak (Q. rubra)
• White oak (Q. alba)
• Eastern white pine
• Red maple
• Shagbark hickory
• American basswood
• White ash

Dry-mesic oak woodland/savanna (oak forests)

• Bur oak
• White oak
• Northern red oak

River floodplain (oak forests)

• Swamp white oak
• Silver maple
• River birch
• Green ash
• American elm
• Bitternut hickory
• Shellbark hickory
• Butternut, black walnut
• Boxelder
• Honeylocust
• Willow
• Cottonwood

Native uses of Fabaceae and Juglandaceae (oak forests)

• Acorns/ nuts: food, oils, jewelry, music, dye
• Wood: tools, fuel
• Leaves: dye, medicines
• Bark: tanning, dye, medicines

threats to oak forests

• spongy moth

• butternut cranker

• phompsis cranker

sugar maple

• range: north-eastern midwest to northern east coast

• not fire tolerant or adapted

• very tolerant (10)

• good stump sprouter when young

• threats: sugar borer, Eutypella canker (cobrahead canker), deicing salts, thrips, moisture stress

american beech

• range: throughout east coast

• many medicinal uses

• very tolerant (10-8)

• vigorous root sprouter

• threats: beech bark disease

American basswood

• range: north-eastern midwest to northern east coast

• gap phase species

• vigorous sprouter

• very fast growth

• moderately tolerant

white ash

• grows poorly on wet, dry, and nutrient poor sites

• does best on fertile, well drained loams with some moisture

• nutrient and moisture demanding species

• moderately tolerant

• rarely dominant

• uses: wood bowls and instruments

• threats: emerald ash borer

Yellow birch

• Moderate tolerance
• Gap-phase regeneration
• Disturbance needed for germination
• Pit & mound topography

eastern hemlock

• Very tolerant (10)
• Once common tannin source for tanning industry (bark is very high
in tannin 7 to 12%)
• Moisture-dependent, esp. for seed germination
• Not fire tolerant
• Acidic soils
• Pit & mound topography
• Deer favorite

• Hemlock woolly adelgid

trembling aspen

▪ Vigorous root sprouter
▪ Extensive clones
▪ Some clones > 40 acres

• Intolerant (1), pioneer, short-lived
• Stands self-thin & self-prune

• vigorous root sprouter

• pulp base for paper industry

• Important for wildlife (over 500 documented relationships)
-Older trees important cavity trees
-Young aspen browsed by ruffed grouse, deer, moose, beaver

• threats: white rot, hypoxylon cranker

balsam poplar

• Intolerant (1)
• Vigorous sprouter
• Shiny leaves, resinous buds, round petiole, odoriferous

paper birch

• Strong stump sprouting
• Intolerant (1-2), short-lived, pioneer w/ disturbance
• Extremely fire sensitive
• Poor competitor
• Wind-disseminated seeds (>350 ft)

• Extremely important Native American tree
• Canoes, lodges, baskets, scrolls, more

• threats: bronze birch borer, birch dieback