February 13, 2008

Tree Walk: Broadleaf tree leaf characteristics

UPDATE: Please visit our new blog site. Read our latest posts: Runnels in Spain and Weekend headlines. As always, we appreciate your readership and comments! ____________________________________________ As flowers bloom blossom and leaves leaf buds unfurl, I am reminded of leaf characters. Several broadleaf tree leaf character diagrams were printed in the Summer 2004 issue of the original local ecology newsletter. The diagrams are included below along with definitions from How to Identify Plants by H.D. Harrington. Simple and compound leaf parts
  • Blade is the "expanded usually flat portion of a leaf or petal."
  • Compound leaf is a leaf "completely separated into 2 or more leaflets." Example: California buckeye.
  • Leaflet is "one of the divisions of a compound leaf."
  • Petiole is the "stalk to a leaf blade or to a compound leaf."
  • Petiolule is the "stalk to a leaflet in a compound leaf."
  • Pinnate is a "compound leaf with the leaflets on 2 opposite sides of an elongated axis."
  • Rachis is the "central elongated axis to an inflorescence or a compound leaf."
  • Simple leaf is a leaf "of only 1 part, not completely divided into separate segments." Example: Pacific madrone.
  • Stipule is an "appendage at the base of the petiole or leaf at each side of its insertion; often more or less united."
Leaf shapes and margins
  • Lanceolate leaves are "lance-shaped; several times longer than wide, broadest toward the base and tapering to apex." Example: willow.
  • Oval leaves are "broadly elliptical, the width over 1/2 the length."
  • Cordate leaves have a "conventional heart shape; the point apical." Example: littleleaf linden.
  • Entire margins do not have teeths or lobes. Example: Eucalyptus.
  • Leaves with serrate margin have "sharp teeth directed forward." Example: coast live oak.
  • Undulate leaves have "gently wavy" margins.
  • Lobed leaves are "technically cut in not over half way to the base or midvein, the sinuses and apex of segments rounded." Example: California sycamore.
Source: Leaf parts: University of Arkansas Botany (original web page is defunct) Leaf shapes and margins: Allan Gardens, Canada (original web page is defunct)

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