Fig. 9.
Flowers.-Parts. The flowers of the Cherry or Apple will show the four kinds of organs that belong to a complete flower. Fig. 9 represents an Apple-blossom. The calyx is the outer row of leaves, more or less united into one piece. The corolla is the row of leaves within the calyx; it is usually the brightest and most conspicuous part of the flower. The stamens are the next organs; they are usually, as in this case, small two-lobed bodies on slender, thread-like stalks. The enlarged parts contain a dust-like material called pollen. The last of the four kinds of parts is found in the center of the flower, and is called the pistil. It is this part which forms the fruit and incloses the seed.
The stamens and the pistil are the essential organs of a flower, because they, and they only, are needed in the formation of seeds. The pollen from the stamen, acting on the pistil, causes the ovules which are in the pistil to grow into seeds.
The calyx and corolla are called enveloping organs, since they surround and protect the essential parts.
The pieces of which the calyx is composed are called sepals. The Apple-blossom has five sepals.
The pieces that compose the corolla are called petals.
Fig. 10.
Kinds of Flowers.-When the petals are entirely separate from each other, as in the Apple-blossom, the flower is said to be polypetalous; when they grow together more or less, as in the Catalpa (Fig. 10), monopetalous; and when the corolla is wanting, as in the flowers of the Oak, apetalous.
When all sides of a flower are alike, as in the Apple-blossom, the flower is regular; when one side of the corolla differs from the other in color, form, or size, as in the Common Locust, or Catalpa, the flower is irregular.
In trees the stamens and pistils are often found in separate flowers; in that case the blossoms containing stamens are called staminate, and those containing pistils pistillate; those that contain both are called perfect. Staminate and pistillate flowers are usually found on the same tree, as in the Oaks, Birches, Chestnut, etc.; in that case the plant is said to be monocious, and all trees of this kind produce fruit. Sometimes, however, the staminate and pistillate flowers are on separate trees, as in the Willows, which are diocious; and then only a portion of the trees-those with pistillate flowers-produce fruit.
Arrangement of Flowers.-Flowers, either solitary or clustered, grow in one of two ways; either at the end of the branches, being then called terminal, or in the axils of the leaves, then called axillary. The stem of a solitary flower or the main stem of a cluster is called a peduncle; the stems of the separate blossoms of a cluster are called pedicels. When either the flowers or the clusters are without stems, they are said to be sessile.
Clusters with Pedicellate Flowers.
Raceme, flowers on pedicels of about equal length, scattered along the entire stem. Locust-tree.
Corymb, like a raceme except that the lower flowers have longer stems, making the cluster somewhat flat-topped; the outer flowers bloom first. Hawthorn.
Cyme, in appearance much like a corymb, but it differs in the fact that the central flower blooms first. Alternate-leaved Cornel.
Umbel, stems of the separate flowers about equal in length, and starting from the same point. Garden-cherry.
Panicle, a compound raceme. Catalpa.
Thyrsus, a compact panicle. Horse-chestnut.
Clusters with Sessile or Nearly Sessile Flowers.
Catkin, bracted flowers situated along a slender and usually drooping stem. This variety of cluster is very common on trees. The Willows, Birches, Chestnuts, Oaks, Pines, and many others have their flowers in catkins.
Head, the flowers in a close, usually rounded cluster. Flowering Dogwood.
Fruit.-In this book a single fruit will include all the parts that grow together and contain seeds, whether from a single blossom or a cluster; there will be no rigorous adherence to an exact classification; no attempt made to distinguish between fruits formed from a simple pistil and those from a compound one; nor generally between those formed from a single and those formed from a cluster of flowers. The fruit and its general classification, determined by the parts easily seen, is all that will be attempted.
As stated before, it is hoped that this volume will not end the student's work in the investigation of natural objects, but that the amount of information here given will lead to the desire for much more.
Berry will be the term applied to all fleshy fruits with more than one seed buried in the mass. Persimmon, Mulberry, Holly. The pome or Apple-pome differs from the berry in the fact that the seeds are situated in cells formed of hardened material. Apple, Mountain-ash. The Plum or Cherry drupe includes all fleshy fruits with a single stony-coated part, even if it contains more than one seed. Peach, Viburnum, China-tree. In some cases, when there is but one seed in the flesh and that not stony-coated, it will be called a drupe-like berry.
The dry drupe is like the Cherry drupe except that the flesh is much harder. The fruit of the Walnut, Hickory, and Sumac.
Fig. 11.
The inner hard-coated parts of these and some others will be called nuts. If the nut has a partial scaly covering, as in the Oaks, the whole forms an acorn. If the coating has spiny hairs, as in the Chestnut and Beechnut, the whole is a bur. The coating in these cases is an involucre. If the coating or any part of the fruit has a regular place for splitting open, it is dehiscent (Chestnut, Hickory-nut); if not, indehiscent (Black Walnut).
Fig. 12.
Dry fruits with spreading, wing-like appendages, as in the Ash (Fig. 11), Maple (Fig. 12), Elm (Fig. 13), and Ailanthus, are called samaras or keys.
Dry fruits, usually elongated, containing generally several seeds, are called pods. If there is but one cell and the seeds are fastened along one side, Pea-like pods, or legumes. Locust. The term capsule indicates that there is more than one cell. Catalpa, Hibiscus.
Fig. 13.
All the dry, scaly fruits, usually formed by the ripening of some sort of catkin of flowers, will be included under the term cone. Pine, Alder, Magnolia. If the appearance of the fruit is not much different from that of the cluster of flowers, as in the Hornbeams, Willows, and Birches, the term catkin will be retained for the fruit also. The scales of a cone may lap over each other; they are then said to be imbricated or overlapping, (Pine); or they may merely touch at their edges, when they are valvate (Cypress). When cones or catkins hang downward, they are pendent. If the scales have projecting points, these points are spines if strong, and prickles if weak. The parts back of the scales are bracts; these often project beyond the scales, when they are said to be exserted. Sometimes the exserted bracts are bent backward; they are then said to be recurved or reflexed.
Chapter V.
Winter Study of Trees.
Table of Contents Many of the peculiarities of trees can be studied much better during the winter and early spring than at any other time of the year. The plan of branching, the position, number, size, form, color, and surface of buds, as well as the arrangement of the leaves within the bud and the peculiarities of the scales that cover them, are points for winter investigation.
General Plan of Branching.-There are two distinct and readily recognized systems of branching. 1. The main stem is excurrent (Fig. 3) when the trunk extends as an undivided stem throughout the tree to the tip; this causes the spire-like or conical trees so common among narrow-leaved evergreens. 2. The main stem is deliquescent (Fig. 4) when the trunk divides into many, more or less equal divisions, forming the broad-topped, spreading trees. This plan is the usual one among deciduous trees. A few species, however, such as the Sweet Gum and the Sugar-maple, show the excurrent stem while young, yet even these have a deliquescent stem later in life. The English Maple and the Apple both have a deliquescent stem very early.
All the narrow-leaved evergreens, and many of the broad-leaved trees as well, show what is called definite annual growths; that is, a certain amount of leaf and stem, packed up in the winter bud, spreads out and hardens with woody tissue early in the year, and then, no matter how long the season remains warm, no additional leaves or stem will grow. The buds for the next year's growth then form and often become quite large before autumn.
There are many examples among the smaller plants, but rarely one among the trees, of indefinite annual growth; that is, the plant puts forth leaves and forms stems throughout the whole growing-season. The common Locust, the Honey-locust, and the Sumacs are illustrations.
Buds.-Buds are either undeveloped...
