Understanding
Vegetative
Morphology

Buds
 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
 Lenticels are breathing pores in the young bark of a woody stem. Scattered lenticels dot the stem between leaf scars.
 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
 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
 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
 Unifacial leaves lack any differentation between adaxial (upper) and abaxial (lower) leaf surfaces.
 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
 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
 As viewed from the side

Venation Types
 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
 Percurrent or scalariform
 Ladderlike
 Reticulate
 Netlike

Pinnate Venation
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Pinnate means ‘feather-like’

Palmate Venation
 Arise from one point at the tip of the petiole, like fingers of an outstretched hand.

Leaf Apex Shapes

Leaf Base Shapes

Leaf Texture
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 Membranous
– very thin
Chartaceous
– papery in texture
 Coriaceous
– very thick

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.

Selected Features of Hairs

Liriodendron tulipifera L.
 Simple leaf
 Pinnate venation
 Truncate apex
 Cordate base
 Long-petioled
 Lobed

Lonicera sempervirens L.
 Perfoliate upper leaves
 Ovate to oblong
 Glaucous beneath on abaxial surface
 Simple leaves

Coleus x hybridus Voss.
 Simple leaf
 Margins serrate
 Acute apex
 Obtuse base
 Pinnate venation

Ricinus communis L.
 Simple leaf
 Palmately veined
 Peltate
 Long-petioled
 5-11 lobed

Gymnocladus dioica
 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.
 Leaves odd-pinnate
 Many leaflets
 Leaflets entire
 Compound leaves

Populus alba L.
 Simple leaf
 Long petioled
 Palmate venation
 Lobed
 Rounded or slightly cordate
 Truncate base

Taraxacum officinale
 Leaves simple
 Leaves oblong, spatulate, or oblanceolate.
 Nearly entire to sinuatepinnatifid.
 Terminal segment largest.

Pinus ponderosa
 Leaves linear
 Leaves needle shaped
 Leaves usually in fascicles of 3.
 5 to 11 inches long.

Cercis canadensis L.
 Leaves simple
 Leaves entire
 Palmately veined.
 Leaves broadly ovate to nearly orbicular.
 Cordate at base.
 Attenuate at apex

Quercus macrocarpa Michx.
 Leaves obovate
 Leaves simple
 Leaves pinnatifid with large terminal lobe.
 Grayish-pubescent abaxial surface.
 Deciduous