Morphology of Plants

Objectives Define plant morphology Describe characteristics of the leaves, stems, roots, and flowers of range plants Describe the anatomy of grasses

Plant Morphology Describes the physical form and external structures of a plant

Roots

Stems Stems—the axes of plants—consist of nodes (where leaves and axillary buds are produced) separated by internodes.

Stems Hollow or PithySolid Not JointedSolidWoody Solid GrassesGrass-likesForbsShrubs (Sedges)(Rushes)

Sharp things  Thorn - sharp-pointed stem/shoot (fr. axillary bud)  Spine - sharp-pointed leaf or leaf part leaf spine (also leaflet spine) stipular spine petiolar spine  Prickle - sharp pointed epidermal appendage

Fig

Fig a

Fig b

Fig c

Stem (Shoot) Types & Modifications

Onion Bulb

Compare ……???

Leaves Important characteristics – Type – Arrangement – Shape – Margin – Veination – Apex

External Parts of the Leaf

Leaf parts Blade Petiole Pair of stipules

The major parts of the leaf are shown in Figure 4.3. In monocots the leaf is almost always broadly sheathing at the base. In taxa such as grasses and gingers there is an adaxial flap or ligule at the junction of the sheath and blade. A leaf that lacks a petiole is said to be sessile.

Leaf Types Simple Compound Compound - PalmateCompound - Pinnate

Leaf Arrangements (Compound)

Leaf Morphology

Leaf Forms

Leaf characteristics

Leaf Shapes Ovate Palmate Linear EllipticLanceolateOblanceolate Wedge-shapedArrow-shapedObovate

Finally, the leaf may have many parallel veins, a pattern termed parallel venation.

Leaf Bases

Leaf Margins

Leaf margins

Leaf Margin - The leaf blade may have lobed or unlobed margins. These and other types of margins are: unlobed, lobed, entire, dentate, serrate, and crenate.

Leaf Margins Serrated Lobed-pinnateLobed-palmate ToothedScallopedEntire

Leaf Tips

Leaf Apex and Base - Various terms relating to the shape of the leaf apex or leaf base include: acute, obtuse, acuminate, emarginate, truncate, and rounded (apex); acute, obtuse, rounded, decurrent, truncate, cordate, lobate, and sagittate (bases).

Leaf Veinations ParallelPinnate PalmateNetted

Leaf Arrangements (Simple)

Leaf Arrangements Alternate OppositeWhorled

Leaf Arrangement

Fig