Under the head of malformations we place cases of atrophy of parts or general dwarfing, due to starvation, the attacks of Fungi or minute insects, the presence of unsuitable food-materials and so on, as well as cases of transformation of stamens into petals, carpels into leaves, and so forth.
Axillary or terminal spikes; they have four stamens, which bear at the back four small herbaceous petal-like structures, and four free carpels, which ripen to form four small green fleshy fruits, each containing one seed within a hard inner coat;.
The parts of the flower are most frequently arranged in fives, or multiples of fives; for instance, a common arrangement is as follows, - five sepals, succeeded by five petals, ten stamens in two sets of five, and five or fewer carpels; an arrangement in fours is less frequent, while the arrangement in threes, so common in monocotyledons, is rare in dicotyledons.
In some orders the parts are numerous, chiefly in the case of the stamens and the carpels, as in the buttercup and other members of the order Ranunculaceae.
Within the perianth, and springing from its sides, or apparently from the top of the ovary, are six stamens whose anthers contain pulverulent pollen-grains.
These stamens encircle a style which is the upward continuation of the ovary, and which shows at its free end traces of the three originally separate but now blended carpels of which the ovary consists.
Described, but with the ovules on the walls of the cavity (not in its axis or centre), a six-parted perianth, a stamen or stamens and stigmas.
In place of the six stamens we commonly find but one (two in Cypripedium), and that one is raised together with the stigmatic surfaces on an elongation of the floral axis known as the "column."
It would appear, then, that the orchid flower differs from the more general monocotyledonous type in the irregularity of the perianth, in the suppression of five out of six stamens, and in the union of the one stamen and the stigmas.
Floral diagram of typical orchid flower; 1, labellum; a, anther; s, rudiments of barren stamens (staminodes).
The order is divided into two main groups based on the number of the stamens and stigmas.
The first Diandreae, has two or rarely three fertile stamens and three functional stigmas.
In Cypripedium two stamens are present, one on each side of the column instead of one only at the top, as in the group Monandreae, to which belong the remaining genera in which also only two stigmas are fertile.
What may be considered the normal number of stamens is, as has been said, six, arranged in two rows.
In Cypripedium two of the outer stamens are wanting; the third - the one, that is, which corresponds to the single fertile stamen in the Monandreae - forms a large sterile structure or staminode; the two lateral ones of the inner series are present, the third being undeveloped.
This arrangement may be understood by reference to the following diagram, representing the relative position of the stamens in orchids generally and in Cypripedium.
Many Thomisidae lurk amongst the stamens and petals of flowers, which they closely match in colour, waiting to seize the insects which visit the blossoms for nectar.
The flowers, which are borne in the leaf-axils at the ends of the stem, are very handsome, the six, generally narrow, petals are bent back and stand erect, and are a rich orange yellow or red in colour; the six stamens project more or less horizontally from the place of insertion of the petals.
The five stamens alternate in position with the lobes of the corolla.
And Sambucus, more rarely two-lipped as in Lonicera; the sepals and petals are usually five in number and placed above the ovary, the five stamens are attached to the corolla-tube, there are three to five carpels, and the fruit is a berry as in honeysuckle or snowberry (Symphoricarpus), or a stone fruit, with several, usually three, stones, as in Sambucus.
The flowers are regular, with four free sepals arranged in two pairs at right angles, four petals arranged crosswise in one series, and two sets of stamens, an outer with two members and an inner with four, in two pairs placed in the middle line of the flower and at right angles to the outer series.
The four inner stamens are longer than the two outer; and the stamens are hence collectively described as tetradynamous.
The petals are generally white or yellow, more rarely lilac or some other colour, and between the bases of the stamens are honey-glands.
Owing, however, to the close proximity of stigma and anthers, very slight irregularity in the movements of the visiting insect will cause self-pollination, which may also occur by the dropping of pollen from the anthers of the larger stamens on to the stigma.
- Two Stamens of Viola tricolor (Pansy), with their two anther lobes and the processp extending beyond them.
One of the stamens has been deprived of its spur; the other shows its spur, c. a row down the centre, are shot out to some little distance from she parent plant.
B, pair of bracteoles below the flower; s, sepals; p, petals; st, stamens; o, ovary.
Evergreen shrub with flattened leaf-like cladodes, native in the southerly portion of England and Wales; the small flowers are unisexual and borne on the face of the cladode; the male contains three stamens, the filaments of which are united to form a short stout column on which are seated the diverging cells of the anthers; in the female the ovary is enveloped by a fleshy staminal tube on which are borne three barren anthers.
Terminating the short annual shoot which bears a whorl of four or more leaves below the flower; in this and in some species of the nearly allied genus Trillium (chiefly temperate North America) the flowers have a fetid smell, which together with the dark purple of the ovary and stigmas and frequently also of the stamens and petals, attracts carrion-loving flies, which alight on the stigma and then climb the anthers and become dusted with pollen; the pollen is then carried to the stigmas of another flower.
The parts of the flower are in fives in calyx, corolla and stamens, followed by two carpels which unite to form a superior ovary.
The slender filaments of the stamens vary widely, often in the same flower; the anthers are linear to ovate in shape, attached at the back to the filament, and open lengthwise.
The method of pollination is to some extent governed by the distribution of the stamens and pistil.
In bisexual or hermaphrodite flowers, that is, those in which both stamens and pistil are present, though self-pollination might seem the obvious course, this is often prevented or hindered by various arrangements which favour cross-pollination.
The cup-shaped flowers have six regular segments in two rows, as many free stamens, and a three-celled ovary with a sessile stigma, which ripens into a leathery many-seeded capsule.
The system of Linnaeus was founded on characters derived from the stamens and pistils, the so-called sexual organs of the flower, and hence it is often called the sexual system.
Nehemiah Grew seems to have been the first to describe, in a paper on the Anatomy of Plants, read before the Royal Society in November 1676, the functions of the stamens and pistils.
Grew speaks of the attire, or the stamens, as being the male parts, and refers to conversations with Sir Thomas Millington, Sedleian professor at Oxford, to whom the credit of the sexual theory seems really to belong.
Camerarius, professor of botany and medicine at Tubingen, published a letter on the sexes of plants, in which he refers to the stamens and pistils as the organs of reproduction, and states the difficulties he had encountered in determining the organs of Cryptogamic plants.
In the latter division of plants he could not detect stamens and pistils, and he did not investigate the mode in which their germs were produced.
The structure of the flower represents the simple type of monocotyledons, consisting of two whorls of petals, of three free parts each, six free stamens, and a consolidated pistil of three carpels, ripening into a three-valved capsule containing many winged seeds.
The sepals and petals are free or more or less united, the stamens as many or twice as many as the petals; the carpels, usually free, are equal to the petals in number, and form in the fruit follicles with two or more seeds.
Increase in size upwards, and at length become crowded, numerous and petaloid, forming a funnel-shaped blossom, the beauty of which is much enhanced by the multitude of conspicuous stamens which with the pistil occupy the centre.