Simple and Compound Leaves

To discriminate between simple and compound leaves, one may locate the axillary bud at the base of a leaf petiole in the node region of the stem. This area signifies the basal end of the entire leaf in both simple and compound leaves.

A simple leaf has only one blade, or lamina, associated with it. There are no leaflets. In singly compound leaves, the leaf is sudivided into leaflets, which attach to a central rachis (axis). The rachis is continuous with the petiole, which attaches to the node region of the stem, where the axillary bud will be found. In doubly, or bipinnately, compound leaves, the primary leaflet lamina is subdivided into smaller secondary leaflets, which attach to a secondary rachis, or rachilla. The secondary rachis attaches to the primary or central rachis. The primary rachis is continuous with the petiole, which attaches to the node region of the stem where the axillary bud will be found.

The number of leaflets in a compound leaf is often constant in many plant species. In even pinnately compound leaves, all of the leaflets are paired. There is no terminal leaflet; thus, the total number of leaf-

Types of Leaves

Simple Leaf And Compound Leaf

Common Patterns of Leaf Lobing and Division

Angiosperm Compound Leaves

Palmately lobed

Pinnate (deeply cut lobes at midribs)

Palmately lobed

Trifoliolate
Palmate Leaves Plants
5-Palmate (digitate)
Digitate Leaf With Leaflets

9-Palmate

Pinnate (deeply cut lobes at midribs)

Ternate Leaf
2-Pinnate (each division divided on 2 axes)

3-Pinnate (each division divided on 3 axes)

9-Palmate

3-Pinnate (each division divided on 3 axes)

lets per leaf is an even number. In odd pinnately compound leaves, there is one terminal, unpaired leaflet at the end of the leaf, making the total number of leaflets an odd number. Trifoliolate leaves have three leaflets, which may have petiolules or be sessile. The term ternate denotes groups of threes.

Leaf blade length is measured from where the blade joins the petiole straight to the tip of the leaf and perpendicular to the width. Width is measured at the widest part of the leaf perpendicular to the length. The petiole is the more or less round stalk that connects the leaf blade to the node region of the stem. Petiole length is measured from the point of attachment of the leaf blade to the node region of the stem. Some species lack petioles or have very short petioles.

The singly compound leaf blade is subdivided into leaflets which attach to a central rachis. The leaflet blade, or lamina, is the flat part of the leaflet. The petiolule is the stalk extending from the base of the leaflet lamina to the rachis. The rachis is continuous with the petiole, which attaches to the node region of the stem, where the axillary bud will be found. Leaflet length is measured from where the leaflet blade joins the petiolule straight to the tip of the leaflet perpendicular to the width. Width is measured at the widest part of the leaflet perpendicular to the length.

In the doubly or bipinnately compound leaf, the primary leaflets are themselves subdivided into still smaller secondary leaflets. The leaflet lamina is attached to a secondary rachis, or ra-chilla. The petiolule extends from the base of the leaflet lamina to the rachilla. The rachilla attaches to the primary or central rachis.

Roger D. Meicenheimer

See also: Leaf anatomy; Leaf arrangements; Leaf margins, tips, and bases; Leaf shapes; Shoots.

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Responses

  • cari
    How to measure length and width of compound leaves?
    8 years ago
  • Murron
    What types of trees have palmately compound leaves?
    7 years ago
  • cotman
    How to classify leaves?
    7 years ago
  • luis
    Is a leaf on a mustard plant compound or simple?
    7 years ago
  • Harding
    Where is the axillary bud on a simple leaf?
    6 years ago
  • LINDA
    What makes a leaf simple or compound?
    4 years ago
  • Kristiina
    Do compound leaves have axillary buds?
    3 years ago
  • sadoc
    What is leaflets lamila and simple and compound leaf?
    3 years ago
  • tanja
    What is the simple and compound leaf and axillary bud structure of this leaf?
    3 years ago
  • elisa
    Is the axil bud is present in the compound leaf?
    3 years ago
  • sabra
    What are the differences between a simple and a compound leaf?
    2 years ago
  • NUGUSE IGGI
    Do compound leaves have axillary or terminal bud?
    2 years ago
  • august autio
    What is a simple laef?
    2 years ago
  • Savanna
    Which plant has pinnately compound leaf at node?
    2 years ago
  • caramella mugwort
    Where do bud prensent in plant compound and smpil leave?
    2 years ago
  • kade
    What is difference between rachilla and petiolule?
    12 months ago

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