Part 2

The pistil (p. 11) is the seed-bearing organ. The pollen-grains which are deposited on its roughened summit throw out minute tubes which reach the little ovules in the ovary below and quicken them into life.

These two kinds of organs can easily be distinguished in any large, simple, complete flower (p. 10). The pollen of the stamens, and the ovules which line the base of the pistil, can also be detected with the aid of an ordinary magnifying glass.

Now, we have been shown that nature apparently prefers that the pistil of a flower should not receive its pollen from the stamens in the same flower-cup with itself. Experience teaches that, sometimes, when this happens no seeds result. At other times the seeds appear, but they are less healthy and vigorous than those which are the outcome of _cross-fertilization_—the term used by botanists to describe the quickening of the ovules in one blossom by the pollen from another.

But perhaps we hardly realize the importance of abundant health and vigor in a plant’s offspring.

Let us suppose that our eyes are so keen as to enable us to note the different seeds which, during one summer, seek to secure a foothold in some few square inches of the sheltered roadside. The neighboring herb Roberts and jewel-weeds discharge—catapult fashion—several small invaders into the very heart of the little territory. A battalion of silky-tufted seeds from the cracked pods of the milkweed float downward and take lazy possession of the soil, while the heavy rains wash into their immediate vicinity those of the violet from the overhanging bank. The hooked fruit of the stick-tight is finally brushed from the hair of some exasperated animal by the jagged branches of the neighboring thicket and is deposited on the disputed ground, while a bird passing just overhead drops earthward the seed of the partridge berry. The ammunition of the witch-hazel, too, is shot into the midst of this growing colony; to say nothing of a myriad more little squatters that are wafted or washed or dropped or flung upon this one bit of earth, which is thus transformed into a bloodless battle-ground, and which is incapable of yielding nourishment to one-half or one-tenth or even one hundredth of these tiny strugglers for life!

So, to avoid diminishing the vigor of their progeny by _self-fertilization_ (the reverse of cross-fertilization), various species take various precautions. In one species the pistil is so placed that the pollen of the neighboring stamens cannot reach it. In others one of these two organs ripens before the other, with the result that the contact of the pollen with the stigma of the pistil would be ineffectual. Often the stamens and pistils are in different flowers, sometimes on different plants. But these pistils must, if possible, receive the necessary pollen in some way and fulfil their destiny by setting seed. And we have been shown that frequently it is brought to them by insects, occasionally by birds, and that sometimes it is blown to them by the winds.

Ingenious devices are resorted to in order to secure these desirable results. Many flowers make themselves useful to the insect world by secreting somewhere within their dainty cups little glands of honey, or, more properly speaking, nectar, for honey is the result of the bees’ work. This nectar is highly prized by the insects and is, in many cases, the only object which attracts them to the flowers, although sometimes the pollen, which Darwin believes to have been the only inducement offered formerly, is sought as well.

But of course this nectar fails to induce visits unless the bee’s attention is first attracted to the blossom, and it is tempted to explore the premises; and we now observe the interesting fact that those flowers which depend upon insect-agency for their pollen, usually advertise their whereabouts by wearing bright colors or by exhaling fragrance. It will also be noticed that a flower sufficiently conspicuous to arrest attention by its appearance alone is rarely fragrant.

When, attracted by either of these significant characteristics,—color or fragrance,—the bee alights upon the blossom, it is sometimes guided to the very spot where the nectar lies hidden by markings of some vivid color. Thrusting its head into the heart of the flower for the purpose of extracting the secreted treasure, it unconsciously strikes the stamens with sufficient force to cause them to powder its body with pollen. Soon it flies away to another plant _of the same kind_, where, in repeating the process just described, it unwittingly brushes some of the pollen from the first blossom upon the pistil of the second, where it helps to make new seeds. Thus these busy bees which hum so restlessly through the long summer days are working better than they know and are accomplishing more important feats than the mere honey-making which we usually associate with their ceaseless activity.

Those flowers which are dependent upon night-flying insects for their pollen, contrive to make themselves noticeable by wearing white or pale yellow,—red, blue, and pink being with difficulty detected in the darkness. They, too, frequently indicate their presence by exhaling perfume, which in many cases increases in intensity as the night falls, and a clue to their whereabouts becomes momentarily more necessary. This fact partially accounts for the large proportion of fragrant white flowers. Darwin found that the proportion of sweet-scented white flowers to sweet-scented red ones was 14.6 per cent. of white to 8.2 of red.

We notice also that some of these night-fertilized flowers close during the day, thus insuring themselves against the visits of insects which might rob them of their nectar or pollen, and yet be unfitted by the shape of their bodies to accomplish their fertilization. On the other hand, many blossoms which are dependent upon the sun-loving bees close at night, securing the same advantage.

Then there are flowers which close in the shade, others at the approach of a storm, thus protecting their pollen and nectar from the dissolving rain; others at the same time every day. Linnæus invented a famous “flower-clock,” which indicated the hours of the day by the closing of different flowers. This habit of closing has been called the “sleep of flowers.”

There is one far from pleasing class of flowers which entices insect-visitors,—not by attractive colors and alluring fragrance—but “by deceiving flies through their resemblance to putrid meat—imitating the lurid appearance as well as the noisome smell of carrion.”[2] Our common carrion-flower, which covers the thickets so profusely in early summer that Thoreau complained that every bush and copse near the river emitted an odor which led one to imagine that all the dead dogs in the neighborhood had drifted to its shore, is probably an example of this class, without lurid color, but certainly with a sufficiently noisome smell! Yet this foul odor seems to answer the plant’s purpose as well as their delicious aroma does that of more refined blossoms, if the numberless small flies which it manages to attract are fitted to successfully transmit its pollen.

Certain flowers are obviously adapted to the visits of insects by their irregular forms. The fringed or otherwise conspicuous lip and long nectar-bearing spur of many orchids point to their probable dependence upon insect-agency for perpetuation; while the papilionaceous blossoms of the Pulse family also betray interesting adaptations for cross-fertilization by the same means. Indeed it is believed that irregularity of form is rarely conspicuous in a blossom that is not visited by insects.

The position of a nodding flower, like the harebell, protects its pollen and nectar from the rain and dew; while the hairs in the throat of many blossoms answer the same purpose and exclude useless insects as well.

Another class of flowers which calls for special mention is that which is dependent upon the wind for its pollen. It is interesting to observe that this group expends little effort in useless adornment. “The wind bloweth where it listeth” and takes no note of form or color. So here we find those

Wan flowers without a name,

which, unheeded, line the wayside. The common plantain of the country dooryard, from whose long tremulous stamens the light, dry pollen is easily blown, is a familiar example of this usually ignored class. Darwin first observed, that “when a flower is fertilized by the wind it never has a gayly colored corolla.” Fragrance and nectar as well are usually denied these sombre blossoms. Such is the occasional economy of that at times most reckless of all spendthrifts—nature!

Some plants—certain violets and the jewel-weeds among others—bear small inconspicuous blossoms which depend upon no outside agency for fertilization. These never open, thus effectually guarding their pollen from the possibility of being blown away by the wind, dissolved by the rain, or stolen by insects. They are called _cleistogamous_ flowers.

Nature’s clever devices for securing a wide dispersion of seeds have been already hinted at. One is tempted to dwell at length upon the ingenious mechanism of the elastically bursting capsules of one species, and the deft adjustment of the silky sails which waft the seeds of others; on the barbed fruits which have pressed the most unwilling into their prickly service, and the bright berries which so temptingly invite the hungry winter birds to peck at them till their precious contents are released, or to devour them, digesting only the pulpy covering and allowing the seeds to escape uninjured into the earth at some conveniently remote spot.

Then one would like to pause long enough to note the slow movements of the climbing plants and the uncanny ways of the insect-devourers. At our very feet lie wonders for whose elucidation a lifetime would be far too short. Yet if we study for ourselves the mysteries of the flowers, and, when daunted, seek their interpretation in those devoted students who have made this task part of their life-work, we may hope finally to attain at least a partial insight into those charmed lives which find

—tongues in trees, books in the running brooks, Sermons in stones, and good in everything.

EXPLANATION OF TERMS

The comprehension of the flower descriptions and of the opening chapters will be facilitated by the reading of the following explanation of terms. For words or expressions other than those which are included in this section, the Index of Technical Terms at the end of the book should be consulted.

The =Root= of a plant is the part which grows downward into the ground and absorbs nourishment from the soil. True roots bear nothing besides root-branches or =rootlets=.

“The =Stem= is the axis of the plant, the part which bears all the other organs.” (Gray.)

A =Rootstock= is a creeping stem which grows beneath the surface of the earth. (See Blood-root and Solomon’s Seal. Pls. I. and X.)

A =Tuber= is a thickened end of a rootstock, bearing buds,—“eyes,”—on its sides. The common Potato is a familiar example of a tuber, being a portion of the stem of the potato plant.

A =Corm= is a short, thick, fleshy underground stem which sends off roots from its lower face. (See Jack-in-the-Pulpit, Pl. CIV.)

A =Bulb= is an underground stem, the main body of which consists of thickened scales, which are in reality leaves or leaf bases, as in the onion.

A =Simple Stem= is one which does not branch.

A =Stemless= plant is one which bears no obvious stem, but only leaves and flower-stalks, as in the Common Blue Violet and Liver-leaf (Pl. LXXXIV.).

A =Scape= is the leafless flower-stalk of a stemless plant. (See Liver-leaf (Pl. LXXXIV.).)

An =Entire Leaf= is one the edge of which is not cut or lobed in any way. (See Rhododendron, Pl. XVI., and Closed Gentian, Pl. C.)

A =Simple Leaf= is one which is not divided into leaflets; its edges may be either lobed or entire. (See Rhododendron, Pl. XVI.; also Fig. 1.)

A =Compound Leaf= is one which is divided into leaflets, as in the Wild Rose, Pink Clover, and Travellers’ Joy (Pl. XXXI., also Fig. 2).

A =Much-divided Leaf= is one which is several times divided into leaflets (Fig. 3).

The =Axil= of a leaf is the upper angle formed by a leaf or leaf-stalk and the stem.

Flowers which grow from the axils of the leaves are said to be =Axillary=.

A cluster in which the flowers are arranged—each on its own stalk—along the sides of a common stem or stalk is called a =Raceme=. (See Cardinal-flower, Pl. LXXXIII.; Shin-leaf, Pl. XVIII.)

A cluster in which the flower-stalks all spring from apparently the same point, as in the Milkweeds, somewhat suggesting the spreading ribs of an umbrella, is called an =Umbel= (Pl. LXXXI.).

A cluster which is formed of a number of small umbels, all of the stalks of which start from apparently the same point, is called a =Compound Umbel=. (See Wild Carrot, Pl. XXVIII.)

A close, circular flower-cluster, like that of Pink Clover or Dandelion, is called a =Head=. (See Oswego Tea, Pl. LXXXII.; Sunflower, Pl. LVII.)

A flower-cluster along the lengthened axis of which the flowers are sessile or closely set is called a =Spike=. (See Vervain, Pl. XCII.; Mullein, Pl. LI.)

A =Spadix= is a fleshy spike or head, with small and often imperfect flowers, as in the Jack-in-the-Pulpit, and Skunk Cabbage (Pls. CII. and CIV., also Fig. 4).

A =Spathe= is the peculiar leaf-like bract which usually envelopes a spadix. (See Jack-in-the-Pulpit and Skunk Cabbage, Pls. CII. and CIV., also Fig. 5.)

A leaf or flower which is set so close in the stem as to show no sign of a separate leaf or flower-stalk, is said to be =Sessile=.

A =Complete Flower= (Fig. 6) is “that part of a plant which subserves the purpose of producing seed, consisting of stamens and pistils, which are the essential organs, and the calyx and corolla, which are the protecting organs.” (Gray.)

The green outer flower-cup, or outer set of green leaves, which we notice at the base of many flowers, is the =Calyx= (Fig. 6 Ca). At times this part is brightly colored and may be the most conspicuous feature of the flower.

When the calyx is divided into separate leaves, these leaves are called =Sepals=.

The inner flower-cup or the inner set of leaves is the =Corolla= (Fig. 6, C).

When the corolla is divided into separate leaves, these leaves are called =Petals=.

We can look upon calyx and corolla as the natural tapestry which protects the delicate organs of the flower, and serves as well, in many cases, to attract the attention of passing insects. In some flowers only one of these two parts is present; in such a case the single cup or set of floral leaves is generally considered to be the calyx.

The floral leaves may be spoken of collectively as the =Perianth=. This word is used especially in describing members of families where there might be difficulty in deciding as to whether the single set of floral leaves present should be considered calyx or corolla (see Lilies, Pls. XLV. and LXXX.); or where the petals and sepals can only be distinguished with difficulty, as with the Orchids.

The =Stamens= (Fig. 7) are the fertilizing organs of the flower. A stamen usually consists of two parts, its =Filament= (F), or stalk, and its =Anther= (A), the little sac at the tip of the filament which produces the dust-like, fertilizing substance called =Pollen= (p.).

The =Pistil= (Fig. 8) is the seed-bearing organ of the flower. When complete it consists of =Ovary= (O), =Style= (Sty.), and =Stigma= (Stg.).

The =Ovary= is the hollow portion at the base of the pistil. It contains the ovules or rudimentary seeds which are quickened into life by the pollen.

The =Style= is the slender tapering stalk above the ovary.

The =Stigma= is usually the tip of the style. The pollen-grains which are deposited upon its moist roughened surface throw out minute tubes which penetrate to the little ovules of the ovary and cause them to ripen into seeds.

A flower which has neither stamens nor pistils is described as =Neutral=.

A flower with only one kind of these organs is termed =Unisexual=.

A =Male= or =Staminate= flower is one with stamens but without pistils.

A =Female= or =Pistillate= flower is one with pistils but without stamens.

The =Fruit= of a plant is the ripened seed-vessel or seed-vessels, including the parts which are intimately connected with it or them.

NOTABLE PLANT FAMILIES

Although the great majority of plant families can only be distinguished by a combination of characteristics which are too obscure to obtain any general recognition, there are some few instances where these family traits are sufficiently conspicuous to be of great assistance in the ready identification of flowers.

If, for instance, we recognize at sight a papilionaceous blossom and know that such an one only occurs in the Pulse family, we save the time and energy which might otherwise have been expended on the comparison of a newly found blossom of this character with the descriptions of flowers of a different lineage. Consequently it has seemed wise briefly to describe the marked features of such important families as generally admit of easy identification.

=Composite Family.=—It is fortunate for the amateur botanist that the plant family which usually secures the quickest recognition should also be the largest in the world. The members of the Composite family attract attention in every quarter of the globe, and make themselves evident from early spring till late autumn, but more especially with us during the latter season.

The most noticeable characteristic of the Composites is the crowding of a number of small flowers into a close cluster or _head_, which head is surrounded by an involucre, and has the effect of a single blossom. Although this grouping of small flowers in a head is not peculiar to this tribe, the same thing being found in the clovers, the milkworts, and in various other plants—still a little experience will enable one to distinguish a Composite without any analysis of the separate blossoms which form the head.

These heads vary greatly in size and appearance. At times they are large and solitary, as in the dandelion. Again they are small and clustered, as in the yarrow (Pl. XXVIII.).

In some genera they are composed of flowers which are all similar in form and color, as in the dandelion, where all the corollas are _strap-shaped_ and yellow; or, as in the common thistle, where they are all _tubular-shaped_ and pinkish-purple.

In others they are made up of both kinds of flowers, as in the daisy, where only the yellow central or _disk-flowers_ are tubular-shaped, while the white outer or _ray-flowers_ are strap-shaped. The flower-heads of the well-known asters and golden-rods are composed of both ray and disk-flowers also; but while the ray-flowers of the aster, like those of the daisy, wear a different color from the yellow disk-flowers, both kinds are yellow in the golden-rod.

If the dandelion or the chicory (Pl. XCVIII.) is studied as an example of a head which is composed entirely of strap-shaped blossoms; the common thistle or the stick-tight (Pl. LVIII.) as an example of one which is made up of tubular-shaped blossoms; and the daisy or the sunflower (Pl. LVII.) as an example of one which combines ray and disk-flowers—as the strap-shaped and tubular blossoms are called when both are present—there need be little difficulty in the after recognition of a member of this family. The identification of a particular species or even genus will be a less simple matter; the former being a task which has been known to tax the patience of even advanced botanists.

Mr. Grant Allen believes that the Composites largely owe their universal sway to their “co-operative system.” He says: “If we look close into the Daisy we see that its centre comprises a whole mass of little yellow bells, each of which consists of corolla, stamens, and pistil. The insect which alights on the head can take his fill in a leisurely way, without moving from his standing-place; and meanwhile he is proving a good ally of the plant by fertilizing one after another of its numerous ovaries. Each tiny bell by itself would prove too inconspicuous to attract much attention from the passing bee; but union is strength for the Daisy as for the State, and the little composites have found their co-operative system answer so well, that late as was their appearance upon the earth they are generally considered at the present day to be the most numerous family both in species and individuals of all flowering plants.” While those of us who know the country lanes at that season when

—ranks of seeds their witness bear,

feel that much of their omnipresence is due to their unsurpassed facilities for globe-trotting. Our roadsides every autumn are lined with tall golden-rods, whose brown, velvety clusters are composed of masses of tiny seeds whose downy sails are set for their aerial voyage; with asters, whose myriad flower-heads are transformed into little puff-balls which are awaiting dissolution by the November winds, and with others of the tribe whose hooked seeds win a less ethereal but equally effective transportation.

=Parsley Family.=—The most familiar representative of the Parsley family is the wild carrot, which so profusely decks the highways throughout the summer with its white, lace-like clusters; while the meadow parsnip is perhaps the best known of its yellow members.

This family can usually be recognized by the arrangement of its minute flowers in umbels (p. 9), which umbels are again so clustered as to form a compound umbel (Wild Carrot, Pl. XXVIII.) whose radiating stalks suggest the ribs of an umbrella, and give this Order its Latin name of _Umbelliferæ_.

A close examination of the tiny flowers which compose these umbrella-like clusters discovers that each one has five white or yellow petals, five stamens, and a two-styled pistil. Sometimes the calyx shows five minute teeth. The leaves are usually divided into leaflets or segments which are often much toothed or incised.

The Parsleys are largely distinguished from one another by differences in their fruit, which can only be detected with the aid of a microscope. It is hoped, however, that the more common and noticeable species will be recognized by means of descriptions which give their general appearance, season of blooming, and favorite haunts.

=Pulse Family.=—The Pulse family includes many of our common wood- and field-flowers. The majority of its members are easily distinguished by those irregular, butterfly-shaped blossoms which are described as _papilionaceous_. The sweet pea is a familiar example of such a flower, and a study of its curious structure renders easy the after identification of a papilionaceous blossom, even if it be as small as one of the many which make up the head of the common pink clover.

The calyx of such a flower is of five more or less—and sometimes unequally—united sepals. The corolla consists of five irregular petals, the upper one of which is generally wrapped about the others in bud, while it spreads or turns backward in flower. This petal is called the _standard_. The two side petals are called _wings_. The two lower ones are usually somewhat united and form a sort of pouch which encloses the stamens and style; this is called the _keel_, from a fancied likeness to the prow of an ancient vessel. There are usually ten stamens and one pistil.