Monday, 4 February 2019

Summer - Composites and Grasses

Summer - Composites and Grasses

By now a succession of blossoms has come and gone  first the early dandelions, then the docks, the plantains, the clovers, and many others. But some plants still keep us guessing. Though they have tall stalks of vigorous leaves, they are taking their time about blooming. When they do finally show their
colors, many of them will prove to be asters, goldenrods, beggar ticks  all members of one family, the Composites.

This is one of the largest and most highly developed of all plant families. It has members that are adapted to a great variety of places and a great variety of conditions. Manv of our loveliest wild flowers, like sunflower and chicory, are composites, and also some of our dullest, like ragweed and mugwort.

These flowers are varied and interesting. Thev are called composites because their heads are composed of dozens  sometimes hundreds — of: tiny florets. If we pull apart the big "flower," or head, of a sunflower, we will find that its dark central disk is made up of a tightly packed group o( very smalltubular florets, each with five petals surrounding stamens and pistil. Around the disk is a ring of yellow rays, each of which is also a true flower. The florets in the sunflower's disk seem small, but they are large compared to those of a plant like goldenrod.
Here the smallest sprig o^ the flower cluster holds several dozen heads, and each head is made up of a group of disk florets and ray florets. There are thousands on every blooming
plant. We can easily pull them apart and see them with the naked eye, but their delicate structure is really clear onlv when they are examined through a magnifying glass.

This general composite pattern has many variations: dande lions are formed entirely of ray florets; burdocks have only tubular disk florets. Some heads are large and bright so that they attract insects; some are tiny and dull and pollinated by the wind. But all o^ them profit from this arrangement of closed-packed masses of flowers. One insect in one visit can dis-
tribute pollen over dozens of them, or else the wind can pick up their pollen in clouds. Each head produces great numbers of encased seeds, and in most composites these seeds are equipped with excellent devices for distribution. Manv have a crown of hairs like the well-known parachutes of the dandelion; others have bristles or are contained in spiny burs. So it is no wonder that the majority or the bright flowers in our city lots belong to this large and thriving family.

However, if we pay attention to less colorful plants, we will find that another big family is just as well represented  the Grasses. Grasses are nearly all wind-pollinated, so they never
have showy flowers. But they do have flowers, usually grouped in dense clusters and always very small. In fact, grass flowers are so small that it is almost impossible to tell anything about them without a magnifying glass, which is a pity because some of them are very beautiful. But even unmagnified grass plants are worth looking at, with their graceful leaves and stems and feathery clusters of flowers.

It is very easy to overlook this beauty and to take the grass family for granted. We are likely to think of it as the back ground for other plants a green carpet in a lawn or a pasture or a prairie. In these places it serves the very important function of keeping the soil from drying up and blowing away or washing away in rain or flood. But it is also useful to man as the source of nearly all his cereals: wheat, rice, corn, and many other grains are the seeds of grasses.

These two enormous plant families, Grasses and Composites, so different in appearance and habit, account for more than half of all the species we will find in our city wild-flower gardens.

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