Eastern Kentucky University General Botany Lab

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Eastern Kentucky University General Botany Lab
LEAVES
Original images for educational, non-commercial
use only. Please credit Ross C. Clark, Ph.D.,
Eastern Kentucky University.
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Leaf model
This shows the structures of a typical dicot
leaf. You should be able to identify epidermal
cells, guard cells, stomata, palisade
mesophyll, spongy mesophyll, collenchyma, bundle
sheath, xylem, phloem, chloroplasts, branch
vein, chloroplasts. (Disregard the
yellow tissue it is a mistake in the model,
since leaves do not have residual procambium.)
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Typical dicot leaf photomicrograph (privet)
Be able to identify and tell the functions of
cuticle, epidermis, guard cell, stoma,
palisade mesophyll, spongy mesophyll, air space,
collenchyma, bundle sheath, branch vein, xylem,
phloem.
midvein close-up
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Shade leaf cross section (dicot)
Compare with sun leaf (sorry, no picture
available yet). Note simple epidermis, larger
air spaces, thinner palisade mesophyll.
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Typical monocot leaf cross section (corn a C4
plant)
Note and tell the functions of cuticle,
epidermis, bulliform cells, guard cells,
trichome, stomata, air spaces, mesophyll, bundle
sheath, xylem, phloem.
close-up
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Xerophytic leaf(oleander a dicot)
Note thick cuticle, multilayered
epidermis, extremely compact palisade
mesophyll, branch veins, small air spaces,
stomatal crypts with trichomes, and very
small stomata (find them!).
Close-up of leaf midvein. Note xylem, phloem
and extensive parenchyma.
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Hydrophytic leaf(Nymphaea water lily)
Note stomata, substomatal air spaces,
palisade mesophyll, extensive aerenchyma,
sclereid. Which side of this leaf rests against
the water, and which side is exposed to the air?
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Leaf abscission layer
Be able to identify petiole, axillary bud
scales, stem, leaf vascular tissue, abscission
zone with cork layers
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Pine leaf cross sections
Cross-section of a bundle of pine needles. These
needles were from a white pine (how do we know?).
Pine needle close-up. Note epidermis, guard
cells and stomata, hypodermis, mesophyll, resin
duct, endodermis (!), xylem, phloem. Summarize
the adaptations that help pine needles conserve
water and maintain reasonable internal leaf
temperatures.
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Here are some other leaf modifications
tendrils
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Trichomes
Trichomes can modify light intensity and rate of
water loss, protect against frost, insects and
herbivores and even form appendages on
insectivorous leaves.
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Hydathodes
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Insectivorous leaves
SUNDEW, with glandular trichomes
VENUS FLYTRAP has trichome triggers
PITCHER PLANT -- and some of the organisms that
live in the pitchers!
BLADDERWORT
Leaf bladders trap small aquatic crustaceans
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Cladophylls Leaves that arent leaves
Cladophylls are stems that serve the
same function as leaves. Cladophylls
sometimes look very much like leaves. This
cactus stem is a cladophyll.