Bentham's Outlines of Botany: Chapter 1: Section 8

§ 8. The Flower in General

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84. A complete Flower (15) is one in which the calyx, corolla, stamens, and pistils are all present; a perfect flower, one in which all these organs, or such of them as are present, are capable of performing their several functions. Therefore, properly speaking, an incomplete flower is one in which any one or more of these organs is wanting; and an imperfect flower, one in which any one of more of these organs is so altered as to be incapable of properly performed its functions. These imperfect organs are said to be abortive is much reduced in size of efficiency, rudimentary if so much as to be scarcely perceptible. But in many works, the term incomplete is specially applied to those flowers in which the perianth is simple of wanting, and imperfect to those in which either the stamens or pistils are imperfect or wanting.

85. A Flower is

dichlamydeous, when the perianth is double, both calyx and corolla being present and distinct.

monochlamydeous, when the perianth is single, whether by the union of the calyx of the calyx or corolla, or the deficiency of either.

asepalous, when there is no calyx.

apetalous, when there is not corolla.

naked, or achlamydeous, when there is no perianth at all.

hermaphrodite or bisexual, when both stamens and pistil are present and perfect.

male or staminate, when there are one or more stamens, but either no pistil at all or an imperfect one.

female or pistillate, when their is a pistil, but either no stamens at all, or only imperfect ones.

neuter when both stamens and pistil are imperfect or wanting.

barren or sterile, when from any cause it produces no seed.

fertile, when it does produce seed. In some works the terms barren, fertile and perfect, are also used respectively as synonyms of male, female, and hermaphrodite.

86. The flowers of a plant or species are said collectively to be unisexual or diclinous when the flowers are either all male or female

monœceious, when male and female flowers are distinct, but on the same plant.

diœcious, when the male and female flowers are on distinct plants.

polygamous, when there are male, female, and hermaphrodite flowers on the same or on distinct plants.

87. A head of flowers is heterogamous when male, female, hermaphrodite and neuter flowers or any two or three of then are included in one head : homogamous, when all the flowers included in one head are alike in this respect. A spike or head of flowers is androgynous when male or female flowers are mixed in it. These terrms are only used in the case of very few Natural Orders.

88. As the scales of buds are leaves undeveloped or reduced in size and altered in shape and consistence, and bracts are leaves likewise reduced in size, and occasionally altered in colour; so the parts of the flower are considered as leaves still further altered in shape, colour and arrangement around the axis, and often more or less combined with each other. The details of this theory constitute the comparatively modern branch of botany called Vegetable Metamorphosis or Homology, sometimes improperly termed Morphology (8).

89. To understand the arrangement of the floral parts, let us take a complete flower, in which moreover all the parts are free from each other, definite in number, i.e. always the same in the same species, and symmetrical or isomerous, i.e. when each whorl consists of the same number of parts.

90. Such a complete symmetrical flower consists usually of either four or five whorls of altered leaves (88), placed immediately one within the other.

The Calyx forms the outer whorl. Its parts are called sepals.

The Corolla forms the next whorl. Its parts, called petals, usually alternate with the sepals; that is to say, the centre of each petal is immediately over or within the intervals between two sepals.

The Stamens form one or two whorls within the petals. If two, those of the outer whorl (the outer stamens) alternate with the petals, and are consequently opposite to, or over the centre of the sepals; those of the inner whorl (the inner stamens) alternate with the outer ones, and therefore opposite to the petals. If there is only one whorl of stamens, they most frequently alternate with the petals; but sometimes they are opposite the petals and alternate with the sepals.

The Pistils forms the inner whorl; its carpels usually alternate with the inner row of stamens.

91. In an axillary or lateral flower the upper parts of each whorl (sepals, petals, stamens, or carpels) are those which are next to the main axis of the stems or branch, the lower parts which are furthest form it; the intermediate ones are said to be lateral. The words anterior (front) and posterior (back) are often used for lower and upper respectively, but their meaning is sometimes reversed if the writer supposes himself in the centre of the flower instead of outside of it.

92. The number of parts in each whorl of a flower is expressed adjectively by the following numerals derived from the Greek :-

mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octo-, ennea-, deca-, etc., poly-,

1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, many-,

prefixed to a termination indicating the whorl referred to.

93. Thus, a Flower is

disepalous, trisepalous, tetrasepalous, polysepalous, etc., according as there are 2, 3, 4, or many (or an indefinite number of) sepals.

dipetalous, tripetalous, polypetalous, etc., according as there are 2, 3, or many petals.

diandrous, triandrous, polyandrous, etc., according as there are 2, 3, or many stamens.

digynous, trigynous, polygynous, etc., according as there are 2, 3, or many carpels.

And generally (if symmetrical) dimerous, trimerous, polymerous, etc., according as there are 2, 3, or many (of an indefinite number of) parts to each whorl.

94. Flowers are unsymmetrical or anisomerous, strictly speaking, when any one of the whorls has a different number of parts from any other; but when the carpels along are reduced in number, the flower is still frequently called symmetrical or isomerous, if the calyx, corolla, and staminal whorls have all the same number of parts.

95. Flowers are irregular when the parts of any one of the whorls are unequal in size, dissimilar in shape, or do not spread regularly round the axis at equal distances. It is however more especially irregularity of the corolla that is referred to in descriptions. A slight inequality in size or direction in the other whorls does not prevent the flower being classed as regular, if the corolla or perianth is conspicuous and regular.

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