586 PLANT mination of the flower stalk, already de- scribed as the receptacle, and also called torus, is ordinarily slightly enlarged to make room for the parts of the flower which are attached to it ; in some cases it is prolonged within the flower, as in the geranium and magnolia ; in the passion flower it elongates and lifts the pistil far above the floral envelopes, and this occurs in other flowers ; in the strawberry it is short and conical to accommodate the numer- ous pistils, and after flowering becomes large and juicy, and is the edible portion, while the proper fruits are the little seed-like bodies upon its surface. The receptacle in the rose, instead of bearing the pistils on its outer surface, is hollowed out, and they are attached to the in- terior of this cavity, the rose fruit or hip, be- ing in structure like an inverted strawberry. In the great water lily (nelumbium), the pistils are immersed in pits in the surface of a broad re- ceptacle, which in fruit is several inches across. In these examples the receptacle has been that of the single flower ; the same name is also given to the end of the stem when enlarged to receive several flowers, as in the composites. Sometimes, as in Dorstenia, the receptacle bears the flowers sunken in cavities in its substance, or, as in the fig, the common receptacle is hol- lowed and has its inner surface studded with minute flowers ; but these forms of the recep- tacle belong to the inflorescence rather than to the flower. The disk or torus, so conspic- uous in the mignonette, sumach, and other flowers, sometimes adherent to the ovary and calyx, is a development of the receptacle. Floral Envelopes. In the flower taken as an example the parts of the calyx and those of the corolla are all alike, and the flower is regular; both series of floral envelopes being present, it is complete; and the parts in each series being five in number, or in the stamens twice five, the flower is symmetrical ; in descriptive botany the opposite of these conditions is ex- pressed by the usual prefix, as irregular, incom- plete, &c. The floral envelopes collectively, whether of two series or only one, are termed the perianth. If one of the sepals or one of the petals is unlike the rest in size or form, the flower becomes irregular ; the violet has three of its petals larger than the other two, and the irregularity is increased by the prolongation of one petal into a spur. In the larkspur the calyx is petal-like and much larger than the co- rolla ; one sepal bears a long spur, which gives the plant its name, while the petals, much small- er and of irregular shapes, are only four. In this case the symmetry of the flower is broken up, one petal being lacking, and this absence or suppression of petals may include more than one, even the whole series, when the flower is apetalous. If but one series of floral envelopes is present, it is always regarded as the calyx, even if, as is often the case, it is petal-like. Many families of plants are constantly apet- alous, and it is not unusual to find apetalous genera in families where the majority of the plants have petals. Other variations are pro- duced by the cohesion of the members of the same series ; the sepals unite by their edges to form a monosepalous or gamosepalous calyx, and the petals to form a monopetalous or ga- mopetalous corolla ; this cohesion varies great- ly in degree, from being confined to the base of the parts up to their union into a complete tube, with every intermediate gradation. "Where the union is more complete with some of the sepals or petals than the others, as in a five- parted flower, where two are united in one body and three in another, a two-lipped calyx or corolla is the result. The united portion of a calyx or corolla of this kind is its tube, and the free portion its limb. The terms used in describing the forms of these are usually derived from common objects, such as bell- shaped, funnel-shaped, wheel-shaped, and oth- ers; while special names are given to other forms, as labiate to the ordinary two-lipped corolla, which is itself capable of a great num- ber of forms, in some of which one of the lips is nearly obsolete ; a two-lipped corolla with its throat closed by a projection, the palate, is called personate. In the composite ligulate or strap-shaped flowers are common, such as the rays of the sunflower ; in this the union of the petals is complete except at one side, which allows the whole to lie flat, though the union is generally manifest at the base. A handful of wild flowers or of single ones from the gar- den will afford numerous illustrations of these modifications of the floral envelopes, and many others. The office of the floral envelopes, the calyx and corolla, being to protect the essen- tial organs, the stamens and pistils, we in most cases find one or both present ; there are naked or achlamydeous flowers in which both are wanting, but here their place is generally sup- plied by a bract, which serves to protect the essential organs ; the graceful and fragrant liz- ard's-tail of our streams (saururus) affords an interesting example of naked flowers. Floral Organs. The stamens (collectively the andrce- cium) are next within the corolla, and present a great variety in form and number; their fila- ment or stalk may be very long, or so short as to be imperceptible ; the anther usually consists of two cells, and these are frequently placed one at each side of the filament at its apex ; the portion of filament between the cells is the connective, and this may be prolonged more or less beyond the anther, and assume various shapes; in the oleander it appears as a long hairy tail ; in some instances it is widened in such a manner as to separate the two cells far apart ; the filament is often broad and flat, and sometimes bears appendages at its base. ID the common pansy and other violets it is on two of the stamens prolonged into a process at the back of the anther much longer than the filament itself. In methods of attach- ment to the filament the anther presents some variety; it may be at the very apex (innate), or with one cell at each side of the filament
