roots, stems, and leaves
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Roots, Stems, and Leaves. 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. Roots. - PowerPoint PPT PresentationTRANSCRIPT
Roots, Stems, and Leaves
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.
Roots
• Obtain water and dissolved nutrients from soil and mycorrhyzae
• Anchor plant• Are point of contact
for mycorrhizal fungi
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 …
Aerial root
Adventitous roots
Root structures
• Tap roots – from primary root
• Fibrous roots – from adventitious or secondary roots
• Tuberous roots – thickened ROOTS– Tubers are thickened
stems Stem, not root
Tuberous root
http://www.museums.org.za/bio/images/enb7/enb07429x_beetroot.jpghttp://trc.ucdavis.edu/egsutter/plb171/VisualMaterial/largePhotoSStruc/TubersPic/tuber-potato99lable.jpg
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
Stems
• 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
Prickles
AlternateSpines
Caudex (pl.: caudices)
• Woody stem that does not or only scarcely extends above ground
Woody stems also have …
• Lenticels • Leaf scars• Bark
http://www.science.siu.edu/plant-biology/PLB304/TwigPics/AcerSaccharinum.jpg
http://www.virtualherbarium.org/treepuzzle/chars/LENTICELS_ABUNDANCE.html
http://home.tiscali.nl/picturesandadicons/dtp/1024x768dtp3/Bark.jpg
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/leaves.jpg
Leaf structure
• Simple– Lobed, Divided,
pinnatifid, palmatifid, pedate, cleft, parted
http://www.discoverlife.org/nh/tx/Plantae/Dicotyledoneae/Aceraceae/Acer/saccharinum/images/JP80036_61.Simple_leaf_position:Opposite.320.jpg
http://www.esb.utexas.edu/mbierner/bio406d/images/pics/ast/Ambrosia%20psilostachya%20lf2.jpg
Compound
• Palmately• Pinnately
– Odd pin
– Even pinnate
Flat, revolute, involute
Revolute
Leaf margins
• Entire, Crenate, Dentate, Serrate
• Crispate or undulate• Spinose
Crenate margins
Dentate margins
Serrate margins
Crisped leaf
Undulate leaves
Spinose leaf
Leaf apices
http://www.eeob.iastate.edu/classes/botany306/terminology/vegetative/images/leaves/apices.jpg
Leaf bases and attachment
http://www.inhs.uiuc.edu/~kenr/prairieplant.terminology/leaf_bases1.jpg