There are eight lessons in this module as follows :
2. Maple (Acer)
3. Birch (Betula)
4. Ash (Fraxinus)
5. Oak (Quercus)
7. Other Deciduous Trees
8. Special Project
Review foundation knowledge in plant identification and culture as needed to properly build expertise specific to deciduous trees.
Develop knowledge in classification, identification and culture of plants, from the genus Acer.
Develop knowledge in classification, identification and culture of plants, from the genus Betula.
Develop knowledge in classification, identification and culture of plants, from the genus Fraxinus.
Develop knowledge in classification, identification and culture of plants, from the genus Quercus.
Develop knowledge in classification, identification and culture of plants, from the genus Prunus.
Review a range of other significant deciduous tree genera not covered previously in this course.
Plan the establishment of a collection of different cultivars of deciduous trees suited to growing in a specified locality.
Extract from the Course :
WHAT MAKES FOLIAGE CHANGE COLOUR IN AUTUMN ?
Deciduous plants shed their leaves in autumn or early winter, and are fully or partially devoid of foliage over the colder months of the year. This is an adaptation that allows the plant to better survive unfavourable conditions (such as extreme cold).
Prior to leaves dropping they undergo a period of senescence.
Senescence is the period during which leaf cells progressively die.
Over this senescence period, tissue at the leaf base progressively dies, until finally a complete section of tissue between the leaf and the stem is dead (At this point there is nothing left to hold the leaf to the stem; so it detaches and drops to the ground).
As senescence occurs, the amount of chlorophyll in the leaf (which gives it the normal green colour) reduces. Chlorophyll is actually only one of many pigments that generally occur in leaves; but it is usually strongest pigment, and for that reason alone, most leaves usually appear green if the plants is healthy.
Other types of pigment chemicals commonly found in leaves include :
- Anthocyanins – Reds, Blues and Purples
- Carotenoids – Yellows and Oranges
Generally Carotenoids also decompose rapidly in Autumn, but Anthrocyanins break down much more slowly.
Often Anthrocyanins can still be at close to 100% normal levels when only 40% of nor;al chlorophyll and carotenoids remain.
Anthrocyanins are produced through chemical processes, from excess sugars inthe leaves, particularly in the presence of bright light. In view of this fact; the level of anthrocyanins will be stronger if the plant has been actively photosynthesising (producing sugars) over summer, combined with lots of bright autumn days (if weather is frequently overcast and dull in late summer and autumn; the production of anthrocyanins is decreased).
Lower temperatures in autumn reduce the movement of sugar around the leaf, so if the weather changes from warm to cool fast, the leaf sugar remains high and anthrocyanins build up; otherwise the levels of these pigments might not be so high.
High levels of anthrocyanins will generally result in more vivid autumn foliage colours.
ENROL NOW AND BECOME A DECIDUOUS TREE EXPERT