Attachment and Arrangement of Leaves on Stem

Arrangement of Leaves on Stem

Alternate

In this type of leaf arrangement, one leaf exists in every node. Example: Hibiscus rosasinensis, Citrus sps.

Opposite

Two leaves are seen at every node in this type of leaf arrangement. Example: Vinca major, Ixora coccinea.

Whorled

This arrangement has more than one leaf at every node around the stem. Example: Nerium oleander

Attachment types of Leaves

Petiolate

Leaf stalk or petiole is present at the leaf angle with stem. Example: Hibiscus rosaninensis, Quercus sps.

Sessile

Leaf is attached to the stem without any petiole. Example: Podocarpus macrophyllus

Peltate

Petiole is present at the bottom surface of the leaf and not at the base or leaf margin. Example: Tropaeolum majus.

Clasping

Partial encircling of the leaf around the stem is clasping. Example: Calendula officinalis.

Sheathing

Leaf base is wrapped around the stem like a grass leaf. Example: Zea mays

Decurrent

Leaf base extends down to create a wing or ridge along the stem. Example: Psidium guajava

Winged petiole

Petiole has leaf-like or membrane-like extension all through the length. Example: Citrus paradise

Winged rachis

A compound leaf stem with a membrane-like extension on either side of the rachis. Example: Rhus copallinum.

 

 Types of Stipules

Simple

These are located on both the sides of the petiole. Ex: Hibiscus rasasinensis

Adnate

These appendages attach to the sides of the petiole. Ex: Trifolium sps., Rosa sps.

Leafy

Leaf-like stipules that are green and serve like foliage on the stem. Ex: Pisum sativum, Delonix regia

 Other Unique Leaf Types

Needle-shaped leaves

Present in Pinus sps.

Needle-like leaves

Leaf margins are rolled back so strongly that the leaf appears tubular just like in Ceratiola ericoides

Awl-shaped and scale-like leaves

Reduced leaf size Ex: Taxodium distichum, Juniperus viginiana