Internode Morphology in Common Blackberry

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Internode Morphology in Common Blackberry
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INTRODUCTION

• Observations
• Blackberry is common in the Jewel Moore Nature
  Reserve
• Blackberry can be an invasive species, just
  like Japanese Honeysuckle.
• It seemed to grow more prolifically in the
  sunlight.
• Question
• Having already studied inter-node length
  dependency on sunlight in invasive honeysuckle,
  we wanted to know if this morphological
  adaptation would be shown in another common
  invasive species.

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INVASIVE SPECIES

• Invasive species are especially problematic in
  areas that have been disturbed by human
  activities.
• Natural disturbances, such as fires, floods,
  tornadoes, landslides, and tree falls also
  provide avenues for invasive species to get
  started.
• Some native plants display invasive growth
  tendencies in their native ranges, often as a
  response to natural or human-caused disturbances.

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CHARACTERISTICS OF COMMON BLACKBERRY

•        Favors moist to slightly dry prairie edges
  along woodlands, open woodlands, areas along
  roadsides and railroads, abandoned pastures, and
  disturbed, burned-over areas in and around
  woodlands
• Arching or trailing stems, to 3.4 m in
  height stems red or green prickles or
  bristles usually present leaves compound, 3-7
  serrate leaflets red or black 'raspberry' fruit
  white flowers. (source http//www.hort.cornell.edu
  /department/faculty/weston/weedfacts/wdfct4a.html
  and http//www.shout.net/jhilty/plantx/cm_blackb
  erryx.htm)
• It prefers sunlight, and produces best in
  full sun, but can tolerate partial shade.
  However, plants don't grow or produce well in
  heavy shade.

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HYPOTHESES
Alternative Hypothesis The internode length of
Rubus allegheniensis will be shorter in the
direct sun and longer in the shade.   Null
Hypothesis There will be no significant
difference in internode length due to varying sun
light availability.
Sun
Shade
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METHODS

• Twenty shoots each were collected from both areas
  of shade and areas of more prolific sunlight
• Starting at the North edge of the reserve, we
  walked South (parallel to Ferris Road) three
  times, moving 20 meters East each time.
• Using hand clippers, we retrieved a sample size
  of 20 individuals from sunny areas and 20
  representing shady areas.
• The internode lengths of sun and shade shoots
  were measured and recorded in millimeters.
• The results were run on Systat to determine the
  mean, standard deviation, and variance between
  variables.

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RESULTS
Figure 1. Comparative average internode lengths
of blackberry plants in the sun and shade.
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RESULTS CONTINUED
Table 1. Statistical results for T-test run on
internode length data.
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DISCUSSION

• The data show a significant difference in the
  average internode lengths of plants from shade
  and from sun.
• The plants grown in shadier areas had
  significantly larger internode lengths.
• Therefore, the null hypothesis can be rejected
  the data supports our functional hypothesis.

Greater
Sun
Shade
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DISCUSSION CONTINUED

• The results are indicative of the Optimal
  Foraging Theorys presence in Rubus
  allegheniensiss growth patterns
•  (The optimal foraging theory states that plants
  and animals attempt to feed in ways that optimize
  acquisition of energy and nutrients.
  http//www.shout.net/jhilty/plantx/cm_blackberryx
  .htm)
• In the sun, more leaves were grown to make use
  of the excess sunlight, causing shorter
  internodes.  
• However, in the shade, instead of growing
  leaves, the plant extended its internode length
  in an attempt to reach the sunlight that it
  prefers.

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INTERNODE LENGTH AS A MORPHOLOGICAL ADAPTATION
Shade
Sun
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CONCLUSIONS

• The morphological variation within this
  species is similar to that of the invasive
  Lonicera japonica (Honey Suckle). Both species
  have the ability to be flexible in response to
  environmental changes.
• This also reflects optimal foraging theory,
  and thus flexible change in plants, by showing
  that plants utilize the resources that are
  available to them by changing growth form and
  resource allocation in response to environmental
  cues.
• (sources class notes, A Framework for Plant
  Behaviors Jonathan Silvertown Deborah M.
  Gordon. Annual Review of Ecology and
  Systematics, Vol. 20. (1989), pp. 349-366.
  Stable URL http//links.jstor.org/sici?sici00664
  16228198929203C3493AAFFPB3E2.0.CO3B2-5,
  and text book)

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ANY QUESTIONS?
A stream bed that has been cleared of an invasive
blackberry species.