Part 123. The Beech Family - Various Plant Groups

Part 123. The beech family (Fagaceae). Examples: chestnut (Figs. 24-26), oaks (Figs. 242, 243, 267), and beech (Fig. 257).

See pages 414, 415 for the formulas of Fagus, Castanea, Quercus, and Fagaceae.

The inflorescences of this family resemble those of the preceding family in being monoecious and in part amentaceous. It is in the bracts and the way they are borne that we find the most significant differences-differences which become more striking as the fruit matures. Indeed, botanists have here met with a morphological problem of more than ordinary difficulty in the preliminary question: What are the homologues of bracts which ripen with a beechnut, a chestnut-bur, or an acorn?

In the staminate inflorescences of beech (Fagus) and chestnut (Castanea) the bracts are obvious enough and are sufficiently like those of the birch family to require no special comment; while the staminate flowers of Quercus are ebracteate. The pistillate flowers of beech are two in a head (Fig. 257) which is enclosed in a little cup or cupule ¹ as it is called, bearing scales or spines on its outer surface. This cup eventually encloses completely the ripening nuts, and when mature splits into four partial valves to set them free. The cupule of chestnuts encloses three flowers, ripens into the spiny bur, and splits sometimes into four valves, and sometimes irregularly. Only one flower is in the scaly cupule of oaks (Quercus), and the single nut which constitutes the acorn is so little covered by the cupule as to make splitting of the cupule unnecessary.

¹ Cu'pule - L. cupula, diminutive of cupa, cup.

Evidently the projections of the beech cup, the spines of the chestnut-bur and scales of an acorn-saucer are homologous, as is also the main part of the cupule of each. But where are the bracts? Do the four divisions of the ripened beech cup and chestnut-bur correspond to so many bracts which in the acorn-saucer remain coalesced? In that case the various outgrowths from the cupule would be regarded as mere projections like the spines on a leaf. This view is held by many botanists. Others maintain that the projections, spines, and scales are the free tips of bracts which have coalesced by their bases to form the body of the cupule. On this view the cupule would be an involucre of many instead of but four bracts. A third view regards the main body of the cupule as stem, that is to say, as a cup-like development of the secondary peduncle, bearing numerous bracts. Thus regarded, the acorn scales, the beech-nut projections, and the branched spines of the chestnut-bur, are homologized with bracts which are entirely distinct and free from the concave inflorescence-stalk. This last theory seems to be the one most easily reconciled with the facts as they appear in other members of the family as well as in those we have studied.²

² This is the view adopted in our formulas, i does duty for the axial part of the ultimate inflorescences; //~ following shows that it becomes woody and cancave like a perigynous torus; while - 4 shows that it dehisces into four valves; or - that it is indehiscent; and Bi °° that it bears numerous dry bracts. The other parts of the formulas should be readily understood from what has preceded.

The family consists of woody plants without oil reservoirs or resinous excretions; but with simple, stipulate leaves; and monoecious inflorescences, the staminate mostly amentaceous, the pistillate more or less enclosed in a cupule, which bears distinct, scaly, or spiny bracts; and the pistils of three or more carpels with axile placentoe.

Part 124. The Beech Order

124. The beech order (Fagales) comprises only the birch and the beech families. These agree in having monoecious inflorescences with the staminate flowers mostly in aments, and the pistillate in spikes or heads; the flowers hypogynous or epigynous; the perianth leaves and stamens distinct and alternate; and the ovary with axile placentce, and more or less completely divided into two or more cavities, all but one of which becomes obliterated in the fruit.

See pages 414, 415 for the formula of Fagales.