Plant Taxonomy: Vegetative Morphology

Dicots

Two cotyledons

Pollen grains have three pores or furrows

Seeds have two seed leaves (cotyledons)

Flower parts in four or five or multiples thereof

Leaves are oval or palmate with net-like veins

Vascular bundles arranged in a ring around the stem

Tap root system

Monocots

One cotyledon

Pollen grains have one pore or furrow

Seeds have one seed leaf (cotyledon)

Flower parts in three or multiples thereof

Leaves are narrow with parallel veins

Vascular bundles are small and spread throughout the stem

Fibrous root system

Roots

The primary one develops from the embryo’s radicle

Secondary/Branch roots

Roots that branch off from the primary root

Adventitious roots

Roots derived from stems or leaves

Primary root types

Tap roots and storage roots

Adventitious root types

Fibrous roots, prop roots, and haustoria roots

Stems

Supports the other structures of the plant

Nodes

The areas where buds, leaves, and stipules are attached

Bulb

Underground stem modification

Small vertical tissue with adventitious roots, surrounded by thick, fleshy storage leaves

Corm

Underground stem modification

Underground storage tissue surrounded with scale-like leaves

Rhizome

Underground stem modification

Underground horizontal stem, covered with scale-like leaves

Tuber

Underground stem modification

Underground storage stem lacking any surrounding leaves

Stolons/Runners

Underground stem modification

Vegetative propagation; not for storage

Thorns

Aboveground stem modification

Tendril

Aboveground stem modification

Long, slender coiling stem

Caudex

Aboveground stem modification

Swollen stem underground or at/near ground level for storage of food reserves or water

Cladode

Aboveground stem modification

A flattened, photosynthetic stem functioning as a leaf

Simple leaf division

Undivided

Ex. Maple leaf

Compound leaf division

Multiple leaflets attached to a rachis

Ex. Ash leaf

Peltate

Leaf attachment where the petiole attaches to the underside of the blade, not at the edge

Petiolate

Leaf attachment where the leaf is attached to the stem byh a stalk called a petiole

Decurrent

Leaf attachment where a leaf whose base extends downward along the stem, creates a wing like appearance

Sessile

Leaf attachment where a leaf is attached directly to the stem without a petiole

Connate

Leaf attachment where a pair of opposite leaves that are fused togtehr at their bases around the stem

Perfoliate

Leaf attachment where the stem appears to pass through the middle of the leaf blade

Sheathing

Leaf attachment where a leaf base wraps around or clasps the stem like a sheath

Phyllotaxy

The ways in which leaves are arranged

Basal phyllotaxy

leaves clustered on short internodes at the base of the stem

Alternate phyllotaxy

Only one leaf attached at each node

Opposite phyllotaxy

Two leaves attached at each node

Whorled phyllotaxy

More than two leaves attached at each node

Glabrous

Smooth, sometimes waxy leaf surface

Pubescent

Leaf surface covered in short, fine hairs

Tomentose

Leaf surface covered in long, wooly hairs

Thorns

Modified stems or shoots contain vascular tissue, are often thick and hard

Spines

Modified leaves or stipules, contain vascular tissue, often thin

Prickles

Outgrowth of the skin, do not contain vascular tissue, often have wide bases

Grasses

Round stem with nodules at leaf base

Hollow all the way to the ground and have joints

Rushes

Round stem that’s not hollow

Sedges

Triangular stem with “edges”