Leaves have three main parts:  The petiole, a stalk-like structure that connects the blade of the leaf to the stem of the plant. Some leaves don’t have petioles,  and are known as sessile leaves. The blade or lamina, usually the largest part of the leaf.  The edge of the leaf or the leaf margin may be described as entire, toothed, or lobed. The oak leaf, for example, is clearly lobed. The blade has many veins, forming a network, carrying water and nutrients, The base, the base is the region of the blade that attaches to the petiole. A leaf is said to be simple if its blade / lamina is undivided, if the ‘teeth’ or lobes do not reach down to the main vein of the leaf.  A compound leaf has several leaflets, which join up with a single leaf stalk or petiole. When identifying tree leaves, it is always important to look for the petiole,   as a single leaflet of a compound leaf can look like a simple leaf.  More details of leaf and tree structure can be found on this link on our website. Now for a challenge.  Can you or your children find a leaf (and name the tree it came from), that Has a serrated / toothed edge Has a lobed margin Has a smooth edge / margin Is a compound, palmate leaf Is a compound, pinnate leaf Is hairy Is not green, but red or a mixture of colours Is more or less circular Is fleshy / succulent Has spines on its edges Is needle shaped Has a thick (waxy?) cuticle or is very shiny Has net venation  is marcescent (might keep you hanging around) Go forage!

Aspens in the United States have been the subject of a number of research studies.  The quaking aspen (Populus  tremuloides) has been used to  study intra-specific variation in a tree species - previous studies have focused on quick growing (herbaceous plants), looking at differences in growth, leaf shape /size, and flowering. the chemistry of the trees’ defences (tannins)  The response to rising carbon dioxide levels - the aspens have grown faster. To add confusion, there is also a European aspen, Populus tremula,  which is known as the quaking aspen, like its American counterpart.  The ‘quaking’ or trembling of the leaves is due to the nature of the leaf stalk or petiole, which has a flattened shape and is very flexible near to the base of the leaf.  The leaves are round with blunt teeth distributed somewhat irregularly around the leaf margin. The leaves of the European Aspen are more coarsely toothed than the American Aspen.  Young leaves have a copper tint before becoming green and then in autumn they turn a vibrant yellow before falling.  Both American and European quaking Aspen species can spread by suckers that form underground away from the parent tree.  The plants so formed are clones, that is they are genetically identical to the parents (ramets). Read more...