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Buds and Leaves
Understanding
Vegetative
Morphology
Buds
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Buds are short embryonic stems.
In angiosperms, buds are found at the nodes, in
the leaf axil, or at the end of a stem.
Buds are especially useful for identifying twigs
in winter condition.
Buds are protected by bud scales, a dense
covering of hairs, and/or a sticky secretion.
Axillary Buds
Terminal Bud
Bud Types
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Accessory Bud
Axillary Bud
Flower Bud
Leaf Bud
Mixed Bud
Naked Bud
Pseudoterminal Bud
Superposed Bud
Terminal Bud
Generalized Angiosperm Stem
Lenticels and Leaf Scars
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Lenticels are breathing pores in the young bark
of a woody stem. Scattered lenticels dot the
stem between leaf scars.
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Leaf scars remain on a stem after the leaves
have fallen. The circles within each scar are
the severed ends of food and water-conducting
bundles.
Lenticels
Leaf Duration
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Leaves may function from a few days to many
years, but most leaves function for only one or
two growing seasons.
Deciduous leaves fall at the end of the
growing season.
Evergreen plants are leafy throughout the
year.
Marcescent leaves wither but do not fall
during the winter or dry season.
Marcescent Leaves
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Many oaks, beeches,
and hornbeams are
marcescent. This may
be an adaptation to
protect winter buds
from browsing animals.
The dried leaves
remaining on the plant
are not very tasty!
Leaf Arrangements
Generalized Angiosperm Leaf
Upper and lower leaf surfaces
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Unifacial leaves lack any differentation
between adaxial (upper) and abaxial (lower)
leaf surfaces.
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Bifacial leaves have definite differences
between adaxial (upper) and abaxial (lower)
leaf surfaces.
Bifacial Leaf
Populus alba L.
Adaxial or upper surface
Abaxial or lower surface
Leaf Structure
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A leaf with a single blade is termed simple.
A leaf with two or more blades, or leaflets, is
said to be compound.
The distinction between simple and compound
leaves can be made by locating an axillary
bud: an axillary bud is subtended by the entire
leaf and never by individual leaflets.
Axillary Buds
Leaf Examples
Simple and Compound Leaves
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Simple Leaves
a. Pinnate Venation
b. Palmate Venation
c. Parallel Venation
Compound Leaves
d. Pinnately Compound
e. Bi-pinnately
Compound
f. Palmately compound
Compound Leaf Examples
Margin Patterns and Leaf Shapes
Leaf Shapes
Leaf Margins
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As viewed from the side
Venation Types
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Primary vein (midvein)
The one most prominent vein in the leaf.
Secondary veins
Veins that branch from the primary vein.
Tertiary veins
Veins that link the secondaries.
Venation Patterns
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Percurrent or
scalariform
Ladderlike
Reticulate
Netlike
Pinnate Venation
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Pinnate means ‘feather-like’
Palmate Venation
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Arise from one point at the tip of the petiole, like
fingers of an outstretched hand.
Leaf Apex Shapes
Leaf Base Shapes
Leaf Texture
Membranous – very thin
Chartaceous – papery in texture
 Coriaceous – very thick
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Surface Texture Terms
Glabrous – lacking hairs.
 Pubescent – with various hairs.
 Glaucous – with a waxy covering.
 Other Terms:
Arachnoid, canescent, hirsute, hispid, lanate,
pilose, puberulent, scabrous, sericeous,
strigose,tomentose,velutinous, villous.
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Selected Features of Hairs
Liriodendron tulipifera L.
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Simple leaf
Pinnate venation
Truncate apex
Cordate base
Long-petioled
Lobed
Lonicera sempervirens L.
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Perfoliate upper leaves
Ovate to oblong
Glaucous beneath on
abaxial surface
Simple leaves
Coleus x hybridus Voss.
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Simple leaf
Margins serrate
Acute apex
Obtuse base
Pinnate venation
Ricinus communis L.
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Simple leaf
Palmately veined
Peltate
Long-petioled
5-11 lobed
Gymnocladus dioica
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Bi-pinnately compound
leaf
Leaflets entire
Pinnae in 3-7 pairs
Larger terminal ones
with 3-7 pairs of ovate,
acute leaflets to 3 inches
long.
Amorpha L.
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Leaves odd-pinnate
Many leaflets
Leaflets entire
Compound leaves
Populus alba L.
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Simple leaf
Long petioled
Palmate venation
Lobed
Rounded or slightly
cordate
Truncate base
Taraxacum officinale
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Leaves simple
Leaves oblong,
spatulate, or
oblanceolate.
Nearly entire to sinuatepinnatifid.
Terminal segment
largest.
Pinus ponderosa
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Leaves linear
Leaves needle shaped
Leaves usually in
fascicles of 3.
5 to 11 inches long.
Cercis canadensis L.
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Leaves simple
Leaves entire
Palmately veined.
Leaves broadly ovate to
nearly orbicular.
Cordate at base.
Attenuate at apex
Quercus macrocarpa Michx.
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Leaves obovate
Leaves simple
Leaves pinnatifid with
large terminal lobe.
Grayish-pubescent
abaxial surface.
Deciduous