Plant Morphology Case Study

Simple Leaf

Blade is undivided

Compound Leaves

Blade is completely divided into leaflets, axillary bud is at the base of the petiole

Palmately Compound

Leaflets radiate from a single point (resembles the palm of the hand)

Pinnately Compound

Leaves originate from the midrib

Doubly Compound

Rachis (stem like structure) originates from the midrib, and then divide into leaflets

Parallel venation

Veins run parallel to each other

Pinnate venation

Main vein extends to from the base to the top of the leaf and secondary veins branching off along the main vein.

Palmate venation

Veins arise from a single point at the base of the leaf

Reticulate venation

Arrangement of veins on a leaf where they form a weblike/netlike structure

Percurrent venation

Ladderlike pattern of venation

Entire margin / Smooth Margin

Entire margin is smooth around the entire leaf edge

Undulate Margin

Wavy Margin

Palmately Lobate

Lobes outlining palmate venation, lobes spreading radially from a point, like fingers on a hand

Pinnately Lobated

Lobes outlining pinnate venation, lobes are arranged on either side of a central axis, like a feather

Serrate Margin

Toothed leaves, margins with sharp teeth oriented toward the apex

Dentate margin

Leaf margin with sharp symmetrical teeth oriented at right angles

Crenate Margins

Teeth are rounded

Lobbed Margins

Indented but not to the midline

Glabrous Leaf

Smooth and possibly glossy leaf

Pubescent/Pilose leaf

Soft or fine short hairs on the leaves and stems of plants

Hypogenous Germination

Hypocotyl remains short and the cotyledons do not emerge from the seed but rather force the radicle and epicotyl axis to elongate out of the seed coat

Epigeous Germination

The radicle emerges from the seed and the hypocotyl elongates, raising the cotyledons, epicotyl, and remains of the seed coat aboveground.

Ovate (Leaf Shape)

Egg shaped leaf, wider at the base of the leaf

Obovate (Leaf shape)

Teardrop shaped leaf, wider at the apex than at the base

Linear (Leaf shape)

Long and thin leaves

Elliptic

Single wide middle portion

Oblong (Leaf shape)

Longer wide middle portion

Lanceolate

Spear shaped leaf

Alternate Phyllotaxy

Leaves arranged with one leaf per node

Opposite (decussate) Phyllotaxy

Leaves arranged as a pair of opposite leaves per node, all pairs are in the same plane

Whorled Phyllotaxy

Leaves are arranged with three or more leaves per node

Distichous arrangement

Leaves arranged in two vertical rows on opposite sides of the stem