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Foster and Kreitzman - Seasons of Life - The complex inter dependency between systems of different types

Identifier

020350

Type of Spiritual Experience

Background

All these are not inter dependency between internal systems, but between systems of different forms

A description of the experience

Seasons of Life – Russell G Foster and Leon Kreitzman

In temperate climes, responding to a variable environmental cue such as moisture or temperature alone as a means of coordinating with seasonal change has its dangers.  A warm January or February can be followed by a cold snap in March.  It is easy for a plant to be 'fooled' by a short run of high temperatures.  Although for some species there may be selective advantages in being the first to flower, because there is less competition around, the risk can be high.

The timing of the change in seasonal conditions has been predictably consistent up to now and many plants use what is effectively a calendar to know the time of year and so when to do what.  For these plants there is a species specific critical day length.  This may be as short  as 6.5 hours in some marigolds (Calendula officinalis) or as much as 16 hours for Japanese morning glory (Ipomoea nil).  The marigolds will only flower when the days are longer than 6.5 hours, whereas the Japanese morning glory will only flower when the day length is shorter than 16 hours.

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There is considerable selective advantage if different plant species reproduce at different times.  This complementarity allows many species to coexist because it reduces overlap in the time period when species compete for limited resources such as space, light and soil nutrients.  So grasses tend to flower early in the growing season and wild flowers later.  Plants of a particular species in the same location tend to flower at the same time every year even though they may have started growing at different times.  This synchronised  flowering helps promote cross-pollination

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The temperature in spring is the main driver for flower bud development and flowering in the common purple lilac (Syringa vulgaris).  The triggering factors for dormancy and reaction to spring temperature are located in the branch tips (buds).  Watch a lilac branch grow close to a warm, south facing wall; spring flowering on this branch will be much earlier than on the branches of the same plant further away from the wall

The source of the experience

Foster and Kreitzmann

Concepts, symbols and science items

Symbols

Science Items

Activities and commonsteps

Activities

Commonsteps

References