In late September in these latitudes a lovely white and yellow aster or daisy with stiff white ray petals surrounding a yellow center is often found blooming along roadsides, empty lots and those areas plant people call “waste places”. I think of these waste places as remnant patches of “green” where nature survives—but—only temporarily.
Though Daisy Fleabane (Erigeron annuus) begins flowering late in summer, its blooms persist well into fall. When most plants have long ago lost their flowers, this native member of the daisy family E. annuus continues to produce lovely eye catching masses of white and yellow flowers.
The plant may grow to a meter to 1.5 meters tall. Its stems and some of the leaves are hairy. The latter are alternate, long, narrow, and smooth (lanceolate shape) and they have no stem or petiole (i.e. are sessile). The base of the leaves clasp the main upright stem of the plant. The flowers are are small, or about 2-3 cm in diameter (about an inch across), have pure white petals and a yellow center. The flower bracts arise from the point at which the leaves arise (the axil) on the stem. Flowering stems are more common on the upright parts of the plant, so that a mature plant may present a bushy appearance of many white and yellow flowers.
The “daisy” designation is a term used in the Middle Ages for this family of plants. Its naming may have been related to the fact that they displayed what appeared to be a yellow sun surrounded by white solar rays. Like the sun itself, the flower was envisioned as the “day’s eye”. That name was corrupted or mis-pronounced over time into our present usage: “daisy”. The scientific name “Erigeron” may have its origin in the stiff white “solar rays” which surround the yellow center. They remind me of the stiff white whiskers of an old man. The genus name “Erigeron” is of Greek origin.The root “eri” = “early” and “geron”= “old man”. Or the “early old man”. Perhaps this is related to the fact that some specie of this genus appear early in the spring and that the ray flowers (at least to me) appear as noted above, like stiff white whiskers of an oldster.
Daisy Fleabane, is classed within the family of Asteracea, (formerly Compositae), or simply the “daisy family of flowers”. The appellation is valid it looks very much like a miniature standard daisy such as the English Daisy (Bellis perennis) or even a Montauk Daisy. But being a “fleabane” is questionable. There is no evidence to suggest it may act to help alleviate an infestation of fleas. The collection with flea-riddence may been a case of simple transfer of reputation. There is a British species, Blue Fleabane (Erigeron acris), which has a bitter taste, hairy texture and distinctive scent. These characteristics suggested to early British herbalists that the plant may have chemical properties that may repel the common flea. The crushed leaves of the dried Daisy Fleabane does emit a faint scent of camphor which may have encouraged homemakers in colonial times to dry the leaves and sew them into sachets for use in closets and clothes closets.
What is interesting about the entire clan of Asters or Compositae family of plants is the “flower” itself. All the ‘flowers” of species in this family a not actual flowers—though they look like ones. They are a compacted mass of tiny, highly modified flowers crammed together to look just like a typical flower—-to fool a bee or a butterfly…and you and I. The name Compositae is perfectly coined to describe this group.
Daisy Fleabane’s attractive white and yellow “flower” is in fact a composite of hundreds of small flowers (or florets) all packed together in a flat receptacle to better attract the attention of pollinators such as bees, certain flies, moths and butterflies.
Compositae have evolved two types of florets: the outer (in E. annuus) white ray flowers or “ray florets”, and in the center of the composite flower yellow “disk florets”. In the Daisy Fleabane the disk florets are brightly colored (yellow) and are “perfect:, i.e. having both stamens and pistil (or male and female parts). (The numbers of these and the dense packing of the disk florets often occur in the Fibonacci squence. This in most often noted and beautifully apparent in the packing of sunflower florets and seeds in the center of the Sunflower (Heilianthus annuus) which is also a member of the Compositae family).
The ray florets are pistilate (or have only the female part). It is the ray florets which produce the long prominent rays or floret petals which forms the outer ring of “petals” of the composite flower. There are about twenty or thirty disk florets with stiff white petals in our local Fleabane flowers. They are often sterile. The disk florets attract bees and butterflies and have special structures which help to facilitate fertilization. It is the disk florets which eventually produce the seeds. These can be seen clearly in a sun flower where the large sunflower seeds are produced within the disk position of the receptacle. While a sunflower “flower” may have hundreds to thousands of ray florets and as many appetizing striped or black seeds. A typical sunflower head may have between 500 to 2000 seeds. Think of that field of Sunflowers in bloom!
The interesting question of the Compositae is why and how did they evolve. It is apparent that being a composite flower offered a flowering plant a survival advantage..but what was it?
Seed bearing plants —gymnosperms—bearing naked seeds which are protected in cones (and are related to modern spruces and pines) arose in the late-middle Paleozoic Era in the Carboniferous Period (about 360 to 300 million years ago). These early plants had no flowers. To produce seeds they had to generate clouds of pollen which was dispersed into the air to pollinate near-by plants. The seeds of gymnosperms like pine and spruce when pollinated produced seeds which had evolved specialized parts like samaras (wings) which helped to disperse the seeds by wind.
About 150 million years later, in the Cretaceous Period (143- 66 MYA) of the Mesozoic Era, a period of warm seas and the continents mostly clumped together closer to the equator—-plants with specialized organs called “flowers”arose. These flowering plants, or angiosperms, had its -ovule enclosed by an egg bearing organ called an ovary which is the basal part of the pistil—or female organ. When pollinated the ovule matures into a hard-coated soeed and the pistil grows into fleshy fruit (or related organ). The fruit was often attractive as a food source to other organisms. These would consume the fruit and carry away the coated seed in its digestive system. The advantage was better, more efficient pollination and seed dispersal. Early flowering plants also used wind pollination to fertilize the flower. These flowers had to produce enormous quantities of pollen to insure pollination.
But this story involves both plants and animals co-evolving into a complimentary “symbiotic” relationship. Bees are insects which had earlier in time evolved to feed on the pollen of flowers. They evolved about 120 million years ago from a form of predatory wasps, in Early Cretaceous.
During the Early Cretaceous Period with the rise of flowering plants some of these wasps began exploiting flowers and began specializing in collecting pollen (and later nectar) from flowers to sustain themselves and their hives.
In the Cretaceous as a result of the explosion of this more efficient and effective means of reproduction competition among flowering plants plants to attract pollinators such as bees, flies, moths, and butterflies competition intensified. By the Late Cretaceous (@ 80MYA) as a result of this competition for pollinators a new family of flowing plants evolved—the Compositae or “daisy family”. Bee pollination became established sometime in Mid Cretaceous and flowering plants had to effectively attract pollinating insects…to produce more seeds..and to complete targeted pollination.
Thus the composite structure evolved which concentrated large numbers of small flowers (or florets) in a format that would more effectively attract pollinators and result in more successfull reproduction. These plants also evolved other structure and physiological adaptations to compete more effectively. One of these was the pappus or fine threads which adhere to their tiny seeds. The pappus which is a modified calyx or base of the true flower. These threads permit the tiny seeds of the Daisy and other Compositeae act as parachutes to help keep the tiny seed lofted in the air and thus permit it to take advantage of wind to disperse seeds more effectively.
Evidence of the rise of the Compositae consist of pollen recovered in Antarctica dated to 80 million years ago or Late Cretaceous. Thus, over a period of about 40 million years (120-80 mya) a new form of plant evolved to more effectively attract insects such as bees and butterflies.
These plants, instead of simply multiplying the number of flowers they produced on a plant…multiplied the reproductive part of the plant and packed it into a more efficient receptacle which would concentrate, color, nectar, and floral fragrances to attract pollinators to effectively pollinate and facilitate reproduction and seed dispersal asl well. As a result, the Asteracea is one of the most successful familes of flowring plants with 30,000 known species. Today it is found on every continent except Antarctica..though 80 million years ago —it was also living there. It is one of the two largest families of flowering plants. The Orchid family is the other one.
From the Cretaceous (80 million years ago) onward flowering plants and bees (as well as other insects) co-evolved with each other to specialize in pollination for plants and exploiting pollen and nectar for the bees and other insects.
Pollination by bees was more efficient. Wind pollinated flowers had to produce enormous quantities of pollen as great cost of energy to the plant. .Much of the pollen was wasted. While pollination by bees was more efficient, more effective and gave bee-pollinated plants and gave the Aster-like of Daisy family (Asteracea or Compositae) advantages in areas where wind was not effective, or over large distances where wind pollen was no likely to occur.
So when you see that lovely Daisy Fleabane or a field of Sunflowers…think of the marvel of the long process of evolution which produced such wonders on nature.
So perhaps we might think more positively of those so called “waste places” where these marvels of nature still persist.
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