Leaves Leaf Homologies Identification Tree shape

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  • LeavesLeaf HomologiesIdentificationTree shape

  • Leaf HomologiesEach leaf has a very different shape and function, yet all are homologous structures, derived from a common ancestral form.

  • What are Homologies?

    Shared similarities between organisms that are derived from common ancestors

  • Broadleaf or Conifer?BROADLEAF (tree with leaves that are thin, flat & usually shed annually)CONIFER (tree that bears cones and has needle-like or scale-like leaves)

  • ConifersNeedle-likeSINGLYFLATlengthSQUARE or 4-SIDEDColorBUNDLES OR CLUSTERSDECIDUOUSEVERGREEN# of needles held in BUNDLESScale-like &Awl like

  • Broadleaf Trees

  • What external features can help identify leaves / trees?Leaf shapeLeaf arrangementLeaf divisionVenationTree shape

  • Leaf shape

  • Leaf arrangementsAlternate

    Each node has one leaf Whorled

    One node producing three or more leaves Basal

    Leaves originating in a cluster at the stems base Opposite

    Two nodes opposite each other on the stem, one leaf arising from each node

  • Leaf ArrangementOpposite vs. Alternate

  • Leaf marginsWhat is a leaf margin???

    The MARGIN of a leaf is the leaf edge.

  • Some broadleaf trees have leaves with smooth edges or ENTIRE MARGINS.

  • Some broadleaf trees have LOBED LEAVES, leaves with projections that shape the edge of the leaf.

  • Some broadleaf trees have TOOTHED MARGINS orSerratedcharacterized by a saw-like edge on the leaf.

  • Leaf DivisionSimple vs. Compound Leaves. What is a leaflet?

  • Leaf divisionSimple LeavesSingle blade

    Compound LeavesBlade divided into leaflets

  • Venation1) Net2)Parallel

  • Tree shape