_Catkin_, [Illustration] 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_, [Illustration] 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. [Illustration: 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_. [Illustration] 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). [Illustration: 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. [Illustration: Fig. 13.]