Those Amazing Flowers

It is remarkable how flowers that so appeal to the human senses really have nothing to do with us. They are simply structures that evolved to allow plants to reproduce in an efficient manner, often via attracting insects, birds or bats for pollination. But the wide variety in shape, color and arrangement is quite incredible. So as we revel in the wonder of flowers during the spring season (especially in northern climates where this represents the renewal of life after a hard winter), let’s pay some attention to the amazing differences in flower structure.

The simplest and most primitive flower type can be represented by a picture of the Fraser magnolia which is blooming now on our Virginia farm. It is a huge single flower which when fertilized results in multiple red seeds which are eaten by birds. The magnolia family is generally considered to be among the earliest types of flowering plants. There are many such single flowers around us such as hibiscus, roses, morning glories, etc.

However we are also surrounded by flowers which are not like these simple single flowers. For example the Walter’s viburnum common in early spring along Florida streams has a small group of relatively tiny flowers which all look the same. Some other viburnums (blackhaw) and dogwoods (red twig) also have this arrangement. Perhaps this grouping of many smaller flowers has advantages in increasing the frequency of fertilization, and in producing more seeds, especially when the pollinators are small.

Yet we see a tendency among those plants with groups of small flowers to develop larger showy structures around the edge of the group. The flowering dogwood is a famous and very obvious example which has white bracts actually derived from leaves around the periphery of a group of very tiny flowers. There are some excellent examples of flowers performing this function among the viburnums. I have shown an example of Mariesii viburnum in which the outer circle of flowers has enlarged petals , except for the innermost petal which is tiny . These much more showy flowers are also sterile and are thus specialized to benefit the group rather than themselves by attracting pollinators.

The ultimate example of a group of flowers with two specialized functions are the composites or asters (the example shown is a daisy) where the outer showy ray flowers totally resemble petals in a simple flower. The central fertile disc flowers are packed in very tightly and bloom in a concentric manner from the outer to the inner areas (see enlarged photo). Thu s what seems to be a single “flower” is actually a collection of many smaller flowers. The aster family has been extremely successful with this high degree of development of their reproductive structure.

So are you convinced that flowers are even more amazing when you understand their incredible strategies to reproduce? Or would you rather just admire them for their singular beauty and not think about their intimate evolutionary adaptations? To my mind more knowledge of the mechanisms involved in plant reproduction just enhances appreciation of the beautiful flowers we enjoy so much.

Bill Dunson, Englewood, FL & Galax, VA
wdunson@comcast.net

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