Roots, Stems, and Leaves
Notes for Biology 2410* at Utah State University
*Plants and fungi: ecosystem essentials
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
http://www.museums.org.za/bio/images/enb7/enb07429x_beetroot.jpg
http://trc.ucdavis.edu/egsutter/plb171/VisualMaterial/largePhotoSStruc/TubersPic/tuber-potato99lable.jpg
Tuberous
root
Stem, not root
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
Prickles
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
Alternate
Spines
Caudex (pl.: caudices)
• Woody stem that does
not or only scarcely
extends above ground
Woody stems also have …
• Lenticels
• Leaf scars
• Bark
http://www.virtualherbarium.org/treepuzzle/chars/LENTICELS_ABUNDANCE.html
http://www.science.siu.edu/plant-biology/PLB304/TwigPics/AcerSaccharinum.jpg
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 byproduct
• 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.esb.utexas.edu/mbierner/bio406d/images/pics/ast/Ambrosia%20psilostachya%20lf2.jpg
http://www.discoverlife.org/nh/tx/Plantae/Dicotyledoneae/Aceraceae/Acer/saccharinum/images/JP80036_61.Simple_leaf_position:Opposite.320.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
Spinose leaf
Crisped leaf
Undulate leaves
Serrate margins
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
Hair types
•
•
•
•
•
•
•
•
Simple
Stellate
Dolabriform
Scalelike
Glochidiate
Barbed
Plumose
Glandular
Vestiture (surface)
• Where is it?
• Lots of words –
problem is COMMON
understanding