Roots, Stems, and Leaves

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Roots, Stems, and Leaves

• Notes for Biology 2410 at Utah State University
• Plants and fungi ecosystem essentials

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Life before reproduction

• Reproduction is essential to a species success
• Plants have to grow to the point that they are
  mature enough, and healthy enough, to reproduce.
• Roots, stems, and leaves are the workhorse
  structures of plants.

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Roots

• Obtain water and dissolved nutrients from soil
  and mycorrhyzae
• Anchor plant
• Are point of contact for mycorrhizal fungi

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Types of roots

• Primary root - from embryo
• Secondary roots from primary root
• Adventitious roots from leaf nodes
• May be modified for support or defense or

Adventitous roots
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Root structures

• Tap roots from primary root
• Fibrous roots from adventitious or secondary
  roots
• Tuberous roots thickened ROOTS
• Tubers are thickened stems

Tuberous root
Stem, not root
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Rhizomes underground stems, not roots

• Rhizomes have nodes and reduced leaves
• Rhizomes often root at nodes
• Rhizomes enable a plant to spread and reproduce
• Rhizomes are most common in mesic and wet habitats

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Stems
Prickles

• Hold up above ground parts of plant transmit
  signals
• Have leaves and may have branches
• Woody or herbaceous
• Leaves and branches may be
• Opposite
• Alternate
• Whorled (Verticillate)
• May have hairs, prickles, thorns, spines

Alternate
Spines
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Caudex (pl. caudices)

• Woody stem that does not or only scarcely extends
  above ground

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Woody stems also have

• Lenticels
• Leaf scars
• Bark

http//www.virtualherbarium.org/treepuzzle/chars/L
ENTICELS_ABUNDANCE.html
http//www.science.siu.edu/plant-biology/PLB304/Tw
igPics/AcerSaccharinum.jpg
http//home.tiscali.nl/picturesandadicons/dtp/1024
x768dtp3/Bark.jpg
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Leaves absolutely vital

• Evaporation surface (essential to nutrient
  transport)
• Energy converters
• Absorb sunlight
• Take in CO2 from air
• Release O2 as by-product
• Food and shelter for others

http//www.huntington.org/BotanicalDiv/TitanPix/le
aves.jpg
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Leaf structure

• Simple
• Lobed, Divided, pinnatifid, palmatifid, pedate,
  cleft, parted

http//www.esb.utexas.edu/mbierner/bio406d/images/
pics/ast/Ambrosia20psilostachya20lf2.jpg
http//www.discoverlife.org/nh/tx/Plantae/Dicotyle
doneae/Aceraceae/Acer/saccharinum/images/JP80036_6
1.Simple_leaf_positionOpposite.320.jpg
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Compound

• Palmately
• Pinnately
• Odd pin
• Even pinnate

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Flat, revolute, involute
Revolute
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Leaf margins

• Entire, Crenate, Dentate, Serrate
• Crispate or undulate
• Spinose

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Leaf apices
http//www.eeob.iastate.edu/classes/botany306/term
inology/vegetative/images/leaves/apices.jpg
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Leaf bases and attachment
http//www.inhs.uiuc.edu/kenr/prairieplant.termin
ology/leaf_bases1.jpg
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Hair types

• Simple
• Stellate
• Dolabriform
• Scalelike
• Glochidiate
• Barbed
• Plumose
• Glandular

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Vestiture (surface)

• Where is it?
• Lots of words problem is COMMON understanding