3 1, 32, although in some plants there is no such distinction, the FIG. article 32, successive stages, flower delivery 90045, in the transition from petals to stamens.

Normally, the parts of successive whorls alternate; but in some cases we find the parts of one whorl opposite or superposed to those of the next some cases, as in the vine-family Ampelidaceae, this seems to be the ordinary mode of development, but the flower delivery 90045 of the stamens on the sepals in many plants, as in the pink family, Caryophyllaceae, is due to the suppression or abortion of the whorl of petals, and this idea is borne out by the development, in some plants of the order, of the suppressed a rule, whenever we find the parts of one whorl superposed flower delivery 90045 those of another we may suspect some abnormality.

A flower is said to be symmetrical when each of its whorls consists of an equal number of parts, or when the parts of any one whorl are multiples of that preceding it. Thus, a symmetrical flower may have five sepals, five petals, five stamens and five carpels, or the number of any of these parts may be ten, twenty or some multiple of five. 23 is a diagram of a symmetrical flower, with five parts in each whorl, alternating with each other. 33 is a diagram of a symmetrical flower of stone-crop, with five sepals, five alternating petals, ten stamens and five the number of parts in the staminal whorl is double that in the others, and in such a case the additional five parts form a second row alternating with the the staminal whorl especially it is common to find additional rows.

34 shows a symmetrical flower, with five parts in the three outer rows, and ten divisions in the this case it is the gynoecium flower delivery 90045 has an additional number of parts. 35 shows a flower of heath, with four divisions of the calyx and corolla, eight stamens in two rows, and four divisions of the fig. flower delivery 90045 36 there are three parts in each whorl; and in fig. 37 there are three divisions of the calyx, corolla and pistil, and six stamens in two all these cases the flower is Monocotyledons it is usual for the staminal whorl to be double, it rarely having more than two rows, whilst amongst dicotyledons there are often very numerous rows of floral envelopes are rarely in which the number of parts in each whorl is the same, are isomerous of equal number; when the number in some of the whorls is different, the flower delivery 90045 is anisomerous of unequal number.

The pistillate whorl is very liable to frequently happens that when it is fully formed, the number of flower delivery 90045 parts is not in conformity with that of the other such circumstances, however, a flower has been called symmetrical, provided the parts of the other whorls are normal, - the permanent state of the pistil not being taken into account in determining fig. 38 shows a pentamerous symmetrical flower, with dimerous pistil.

Symmetry, then, in botanical language, has reference to a certain definite numerical relation of parts. A flower in which the parts are arranged in twos is called dimerous; when the parts of the whorls are flower delivery 90045, four or five, the flower flower delivery 90045 trimerous, tetramerous or pentamerous, symmetry which is flower delivery 90045 commonly met with is trimerous and pentamerous - the former occurring generally among monocotyledons, the latter among and tetramerous symmetry occur also among dicotyledons.

article The various parts flower delivery 90045 the flower have a certain definite relation to the axis. 35, one sepal is next the axis, flower delivery 90045 is called superior or posterior; another is next the bract, and is inferior or anterior, and the other two are lateral; and certain terms are used to indicate that position. A plane passing through the anterior and posterior sepal and through the floral axis is termed the median plane of the flower; a plane cutting it at right angles, and passing through the lateral sepals, is the lateral plane; whilst the planes which bisect the ?.

11 4lll!0 FIG. - Flower delivery 90045 section of a symmetrical pentamerous flower of Stone-crop Sedum, consisting of five sepals s, five petals p alternating with the sepals, ten stamens a in two rows, and five carpels c containing dark lines d on the outside of the carpels are glands. - Diagram of the flower of Flax Linum, consisting of five sepals s, five petals p, five stamens a, and five carpels c, flower delivery 90045 of which is partially divided into dots represent a whorl of stamens which has is pentamerous, complete, symmetrical and regular.

article - Diagram of the symmetrical trimerous flower of Fritillary Fritillaria. - Diagram of the flower of Saxifrage Saxifraga tridactylites. The calyx and corolla consist of five parts, the stamens are ten in two rows, while the pistil has only two parts developed. angles formed by the lateral and median planes are the diagonal planes and in these flowers the petals which alternate with the sepals are cut by the diagonal planes.

while the odd sepal is the order Scrophulariaceae one of the two carpels is posterior and the other anterior, whilst in Convolvulaceae the carpels are arranged the twisting of a part makes a change in the position of other parts, as in Orchids, where the twisting of the ovary changes the position of the labellum.

When the different members of each whorl are like in size and shape, the flower is said to be regular; while differences in the size and shape of the parts of a whorl make the flower irregular, as in the papilionaceous flower, represented in fig. When a flower can be divided by a single plane into two exactly similar parts, then it is said flower delivery 90045 be flowers as Papilionaceae, Labiatae, are contrast with this are flower delivery 90045 or actinomorphic flowers, which have a radial symmetry and can be divided by several planes into several exactly flower delivery 90045 portions; such are all regular, symmetrical the parts flower delivery hk any whorl are not equal to or some multiple of the others, then the flower 15 want of symmetry may be brought about flower delivery 90045 various in the symmetrical arrangement as well as in the completeness and regularity of flowers has been traced to suppression or the non-development of parts, degeneration flower delivery 90045 imperfect formation, cohesion or union of parts of the same whorl, adhesion or union of the parts of different whorls, multiplication of parts, and deduplication sometimes called chorisis or splitting of parts.

article Cohesion, or the union of parts of the same whorl, and adhesion, or the growing together of parts of different whorls, are causes of change both as regards form and in Cucurbita the flower delivery 90045 are originally five in number, flower delivery 90045 subsequently some cohere, so that three stamens only are seen in the mature is well seen in the gynostemium of orchids, where the stamens and stigmas Capparidaceae the calyx and petals flower delivery 90045 their usual position, but the axis is prolonged in the form of a gynophore, to which the stamens are united.

Multiplication, or an increase of the number of parts, gives rise to have already alluded to the interposition of new members in a takes place chiefly in the staminal whorl, but usually the additional parts produced form a symmetrical whorl with the some instances, however, this is not the in the horse-chestnut there is an interposition of flower delivery 90045 stamens, and thus seven stamens are formed in the flower, which is asymmetrical.

Parts of the flower are often increased by a process of deduplication, or chorisis, i. the splitting of a part so that two or more parts are formed out of what was originally in Cruciferous plants the staminal whorl consists of four long stamens and two short ones tetradynamous. The symmetry in the flower is evidently dimerous, and the abnormality in the androecium, where the four long stamens are opposite the posterior sepals, takes place by a splitting, at a very early stage of development, of a single outgrowth into cases of what was considered chorisis are in reality due to the development of stipules from the staminal in Dicentra and Corydalis there are six stamens in two bundles; the central one of each bundle alone is perfect, the lateral ones have each only half an anther, and are really stipules formed from the staminal of stamens also produces apparent want of symmetry; thus, in the so-called polyadelphous stamens of Hypericaceae there are really only five stamens which give off numerous branches, flower delivery 90045 the basal portion remaining short, the branches have the appearance of separate flower delivery 90045, and the flower thus seems asymmetrical.

article Cultivation has a great effect in causing changes in the various parts of alterations in form, size, number and adhesion of parts are due to the art of the changes in the colour and forms of flower delivery 90045 thus produced are the dahlia the florets are rendered quilled, and are made to assume many glowing pelargonium the flowers have been rendered larger and more showy; and such is FIG. - Flower of Pea Pisum sativum, showing a papilionaceous corolla, with one petal superior st called the standard vexillum, two inferior car called the keel carina, and two lateral a called wings alae.

also the case with the Ranunculus, the auricula and the flowers, with spurred petals in their usual state, as columbine, are changed so that the spurs disappear; and others, as Linaria, in which one petal only is usually spurred, are altered so as to have all the petals spurred, and to present what are called pelorian varieties.