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.
These flowers are peculiarly adapted to cross-fertilization through insect agency, although one might imagine the contrary to be the case from the relative positions of stamens and pistil. In the pea-blossom, for example, the hairy portion of the style receives the pollen from the early maturing stamens. The weight of a visiting bee projects the stigma and the pollen-laden style against the insect's body. But it must be observed that in this action the stigma first brushes against the bee, while the pollen-laden style touches him later, with the result that the bee soon flies to another flower on whose fresh stigma the detached pollen is left, while a new cargo of this valuable material is unconsciously secured, and the same process is indefinitely repeated.
Mint Family. - A member of the Mint family usually exhales an aromatic fragrance which aids us to place it correctly. If to this characteristic is added a square stem, opposite leaves, a two lipped corolla, four stamens in pairs - two being longer than the others - or two stamens only, and a pistil whose style (two-lobed at the apex) rises from a deeply four-lobed ovary which splits apart in fruit into four little seed-like nutlets, we may feel sure that one of the many Mints is before us.
Sometimes we think we have encountered one of the family because we find the opposite leaves, two-lipped corolla, four stamens, and an ovary that splits into four nutlets in fruit; but unless the ovary was also deeply four-lobed in the flower, the plant is probably a Vervain, a tribe which greatly resembles the Mints. The Figworts, too, might be confused with the Mints did we not always keep in mind the four-lobed ovary.
Mustard Family. - The Mustard family is one which is abundantly represented in waste places everywhere by the little shepherd's purse or pickpocket, and along the roadsides by the yellow mustard, wild radish, and winter-cress (PL XLII.).
Its members may be recognized by their alternate leaves, their biting harmless juice, and by their white, yellow, or purplish flowers, the structure of which at once betrays the family to which they belong.
The calyx of these flowers is divided into four sepals. The four petals are placed opposite each other in pairs, their spreading blades forming a cross which gives the Order its Latin name Cruciferce. There are usually six stamens, two of which are inserted lower down than the others. The single pistil becomes in fruit a pod. Many of the Mustards are difficult of identification without a careful examination of their pods and seeds.
Orchis Family. - To the minds of many the term orchid only suggests a tropical air-plant, which is rendered conspicuous either by its beauty or by its unusual and noticeable structure.
This impression is, perhaps, partly due to the rude print in some old text-book which endeared itself to our childish minds by those startling and extravagant illustrations which are responsible for so many shattered illusions in later life; and partly to the various exhibitions of flowers in which only the exotic members of this family are displayed.
Consequently, when the dull clusters of the ragged fringed orchis, or the muddy racemes of the coral-root, or even the slender, graceful spires of the ladies' tresses are brought from the woods or roadside and exhibited as one of so celebrated a tribe, they are usually viewed with scornful incredulity, or, if the authority of the exhibitor be sufficient to conquer disbelief, with unqualified disappointment. The marvellous mechanism which is exhibited by the humblest member of the Orchis family, and which suffices to secure the patient scrutiny and wondering admiration of the scientist, conveys to the uninitiated as little of interest or beauty as would a page of Homer in the original to one without scholarly attainments.
The uprooting of a popular theory must be the work of years, especially when it is impossible to offer as a substitute one which is equally capable of being tersely defined and readily apprehended; for many seem to hold it a righteous principle to cherish even a delusion till it be replaced by a belief which affords an equal amount of satisfaction. It is simpler to describe an orchid as a tropical air-plant which apes the appearance of an insect and never roots in the ground than it is to master by patient study and observation the various characteristics which so combine in such a plant as to make it finally recognizable and describable. Unfortunately, too, the enumeration of these un-sensational details does not appeal to the popular mind, and so fails to win by its accuracy the place already occupied by the incorrect but pleasing conception of an orchid.
For the benefit of those who wish to be able to correctly place these curious and interesting flowers, as brief a description as seems compatible with their recognition is appended.
Leaves. - Alternate, parallel-nerved.
Flowers. - Irregular in form, solitary or clustered, each one subtended by a bract.
Perianth. - Of six divisions in two sets. The three outer divisions are sepals, but they are usually petal-like in appearance. The three inner are petals. By a twist of the ovary what would otherwise be the upper petal is made the lower. This division is termed the tip; it is frequently brightly colored or grotesquely shaped, being at times deeply fringed or furrowed; it has often a spur-like appendage which secretes nectar; it is an important feature of the flower and is apparently designed to attract insects for the purpose of securing their aid in the cross-fertilization which is usually necessary for the perpetuation of the different species of this family, all of which give evidence of great modification by means of insect-selection.
In the heart of the flower is the column; this is usually composed of the stamen (of two in the Cypripediums), which is confluent with the style or thick, fleshy stigma. The two cells of the anther are placed on either side of and somewhat above the stigma; these cells hold the two pollen masses.
Darwin tells us that the flower of an orchid originally consisted of fifteen different parts, three petals, three sepals, six stamens, and three pistils. He shows traces of all these parts in the modern orchid.
"A fresh footpath, a fresh flower, a fresh delight"