sugary solution that is formed in the flower by little collections of cells called the nectar glands. The nectar glands are usually so placed that to get to them the insect must first brush the stamens and pistil of the flower. Frequently the location of the nectaries (nectar glands) is made conspicuous by brightly colored markings on the corolla of the flower. The row of dots seen in the tiger lily is an example. You may easily find other instances of nectar guides, as they are called. Look for them in any of the common fall flowers.

Mouth Parts of the Bee.-The mouth of the bee is adapted to take in the foods we have mentioned, and is used for many other purposes for which a more highly developed animal, man, would use the hands and fingers. The honeybee laps or sucks nectar from flowers, it chews the pollen, and it uses part of the mouth as a trowel in making the honeycomb. A glance at the figure shows us that the mouth parts of the bee are complex. The parts consist of a pair of very small jaws or mandibles, certain other structures, maxillæ, part of the lower lip called the labial palps, and a long tonguelike structure called the ligula. Watch a bee on a flower. Try to make out what parts of the mouth are used in taking nectar and in gathering pollen. Make a drawing of the bumblebee, twice natural size, showing as many of the structures we have just described as possible. Label the parts care

clover.

Photograph by Davison.

fully and put it in your notebook. It will be interesting to compare this drawing with the drawings you make later in the year when you study other insects. You will be surprised to find how much you improve in drawing.

Other Insect Visitors. Other insects besides the bee are pollen carriers for flowers. Among the most useful are moths and butterflies. Both of these

insects feed only on nectar, which they suck through a long tubelike proboscis. The heads and bodies of these insects are more

or less thickly covered with hairs, and the wings are thatched with hairlike, tiny scales. All these structures are of use to the flower because they collect and carry pollen. On each side of the head of a butterfly is a long, fluffy structure, the palp. This collects and carries a large amount of pollen, which is deposited upon the stigmas of other flowers when the butterfly pushes its head down into the flower tube after nectar.

Flies and some other insects are agents in cross-pollination, as we shall see during some of our later studies. Humming birds.

are also active agents in some flowers. Snails are said in rare instances to carry pollen. Man and the domesticated animals undoubtedly frequently pollinate flowers by brushing past them through the fields.

Field Flowers. - Let us now take up some common wild flowers easily found in the fall of the year, and work out the relation of the parts of the flower to its insect visitors. Remember that the important part of these exercises is to find how and by what means the flower is adapted or fitted to receive the visits of insects. This work can be done best on field trips, but it can readily be modified so as to be useful as a schoolroom exercise.

A humming bird just about to cross-pollinate a flower.

The Evening Primrose (Onagra biennis). - The habitat preferred by this flower is dry fields, roadsides, or waste places. The yellow flowers are found in long, upright, densely crowded clusters. A flower cluster in which the individual flowers have no flower stalks or pedicles, with one main axis to the cluster, is called a spike. Notice that young and old flowers and fruits are all on the same cluster. Where are the youngest flowers located in the cluster? Is there any flower at the end of the main stalk? Could you determine in advance the length of the flower cluster? Such a cluster is said to be indeterminate. Why? Study a single open flower. Note the calyx and corolla; are the parts distinct? How many petals do you find? Notice that there are eight stamens and that the stigma is four-parted. Cut the ovary in cross section and see how many locules there are.

When a flower has each circle of parts, as the sepals, petals, stamens, and pistils made up of a certain number of divisions, or when they appear in multiples of that number, the flower is said to be symmetrical. Here we see a very striking example of symmetry in a flower.

The chief attraction to insects is the nectar which is formed in nectar glands at the base inside the slender tubular corolla. Information is given to the insects of the contents by a faint, sweet odor. This flower is not visited by many day-flying insects. Can you determine the names of any that do come by day? At night the flower opens more widely and the scent becomes much more noticeable. Moths are its chief night visitors. The long proboscis is thrust into the flower and quickly withdrawn, but usually a little pollen is carried off on the palps, to be left on the next flower visited.

Try to determine what other insects, if any, visit the evening primrose at night.

Draw a single flower split open lengthwise to show the position of the parts, and especially any adaptations to insect pollination. Look for any special means for the prevention of self-pollination. Label all the parts.

Butter and Eggs (Linaria linaria). — From July to October this very abundant weed may be found especially along roadsides and in sunny fields. The flower cluster forms a tall and conspicuous spike. Can you see any advantages to a plant in bearing its flowers in clusters?

Describe the general shape of the flowers. The corolla projects into a spur on the lower side; an upper two-parted lip shuts down upon a lower three-parted lip. The four stamens are in pairs. What is peculiar in their position and structure? Notice the position of the pistil. Could selfpollination easily occur? (The stamens of two lengths may allow selfpollination in stormy weather, when insects fail to reach the flower.)

Notice that certain parts of the corolla are more brightly colored than the rest of the flower. This color is a guide to insects. How might it help

them in this flower?

Push a pencil between the two lips of the flower. Does the pencil touch the stamens? If a bee pushes aside the lips, would it be likely to take any pollen from the stamens? Do you think other insects than bees would be likely to aid the flower in pollination?

Draw the flower from the side, cut lengthwise to show the position of stamens and pistil. Make this drawing diagrammatic.

Moth Mullein (Verbascum blattaria). The moth mullein is one of the most beautiful weeds, despite the fact that few blossoms are found at any given time. The plant flourishes on dry waste land, roadsides, and open fields. It was introduced into this country and has since become common here and in Canada.

The flowers are found in a long, loose raceme. A raceme is like a spike, except that each flower has its own flower stalk developed. Has this cluster yellow or white flowers? Into how many parts is the calyx divided? The corolla? Is the corolla perfectly regular? Notice the five stamens; is there anything peculiar about the filaments? Are they all of the same length? In spite of the fact that the flower is called moth mullein, it is not pollinated to any extent by moths. Bees and flies are the chief pollen bearers. Bees which alight on this flower do so for the purpose of collecting pollen. This they usually gather from the short stamens while they cling to the longer ones. As the bee lights on another flower, the pollen on the under side of the body is transferred to the stigma of this flower.

Draw the flower from above, twice natural size.

Jewel Weed (Impatiens biflora). — One of the most prevalent of all our

brookside flowers is the jewel weed. It well deserves its name, a pendent flaming jewel of orange.

The flower is very irregular in shape. Are the flowers single or in clusters? The sepals as well as the petals are colored. The former are three in number, one of which is saclike in shape and contracted at one end into a spur. The petals are also three in number. Open the flower. Notice how short the filaments of the five stamens are. Make a note of their position with relation to the pistil. Would self-pollination be possible in this flower?

If it is possible to study jewel weed out of doors in its native habitat, it will be found that humming birds are the visitors which seem best adapted to cross-pollinate the flower. A careful series of observations by some girl or boy upon the cross-pollination of this flower might add much to our knowledge regarding it.

Jewel weed has the habit of producing (usually in the fall) inconspicuous flowers which never open but which produce seeds capable of germination and growth. Such flowers are said to be cleistogamous. In England, where the plant has been introduced, it is found to produce more cleistogamous flowers than showy ones, and the showy ones do not produce seed. There are no humming birds in England, and without this means of pollination the cleistogamous form prevails. Make a front view drawing of the flower of jewel weed twice natural size.

Many other examples of adaptations to secure cross-pollination by means of the visits of insects might be given. The moun

Pronuba pollinat

tain laurel, which makes our hillsides so beautiful in late spring, shows a remarkable adaptation in having the stamens caught in little pockets of the corolla. The weight of the visiting insect on the corolla releases the anther of the stamen from the pocket in which it rests, and the body of the visitor is dusted with pollen.1

The milkweed or butterfly weed (Asclepias cornuti) is another example of a flower adapted to insect pollination.2

Still another example of cross-pollination is found in the yucca, a plant somewhat like the Spanish ing pistil of bayonet. In this flower the stigmatic surface is above the anther, and the pollen is sticky and could not be transferred except by insect aid. This is accomplished in a remarkable manner. A little moth called the Pronuba

yucca.

1 See Hunter and Valentine, Manual, page 57.

2 For an excellent account of cross-pollination of this flower, the reader is referred to W. C. Stevens, Introduction to Botany. Orchids are well known to botanists as showing some very wonderful adaptations. For simple reference reading, see Coulter, Plant Relations. A classic easily read by children is Darwin, On the Fertilization of Orchids.

gathers pollen from an anther, flies away with this load to another flower, there deposits an egg in the ovary of the pistil, and then rubs its load of pollen over the stigma of the flower. The young hatch out and feed on the young seeds which have been fertilized by the pollen placed on the stigma by the mother. They eat some of the developing seeds and then bore out of the seed pod and escape to the ground, leaving the plant to develop the remaining seeds without molestation.

The fig insect (Blastophaga grossorum) is another member of the insect tribe that is of considerable economic importance. It is only in recent years that the fruit growers of California have discovered that the fertilization of the female flowers is brought about by a gall fly which bores into the young fruit.'

Pollination by the Wind. Not all flowers are dependent upon insects for cross-pollination. Many of the earliest of spring flowers appear almost before the insects do. These flowers, needing no conspicuous colors or showy corolla to attract insects, often lack this part altogether. In fact we are apt to entirely overlook the flowers which appear in the spring upon our common forest and shade trees. In many trees, as, for example, the willow, the flowers appear before the leaves come out. Such flowers are dependent upon the wind to carry pollen from the stamens of one flower to the pistik of another. Most of our common trees, oak, poplar, maple, and others, are cross-pollinated almost entirely by the wind.

Among the adaptations that a wind-pollinated flower shows are: (1) The development of very many pollen grains to each ovule. In one of the insect-pollinated flowers, that of the nightblooming cereus, the ratio of pollen grains to ovules is about eight to one. In flowers which are to be pollinated by the wind, a large number of the pollen grains never reach their destination and are

1 The teacher is referred to Year Book of the Department of Agriculture for 1900 for data on the insect which pollinates the Smyrna fig.