Trees of the Northern United States. A. C. Apgar
toward the light, as though full of holes; membranous, thin, soft, and rather translucent; thick, thin, etc.
Duration.—Evergreen, hanging on the tree from year to year. By noticing the color of the different leaves and their position on the twigs, all evergreen foliage can readily be determined at any time during the year. Deciduous, falling off at the end of the season. Fugacious, falling early, as the stipules of many leaves.
Chapter IV.
Flowers and Fruit.
The author hopes that those who use this work in studying trees will become so much interested in the subject of Botany as to desire more information concerning the growth and reproduction of plants than can here be given. In Professor Asa Gray's numerous works the additional information desired may be obtained: "How Plants Grow" contains an outline for the use of beginners; "The Elements of Botany" is a more advanced work; while the "Botanical Text Book", in several volumes, will enable the student to pursue the subject as far as he may wish. In this small book the barest outline of the parts of flowers and fruit and of their uses can be given.
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 monœcious, 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 diœcious; 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