Similarly in the sporophylls of some cycads the bundles are endarch near the base and mesarch near the distal end of the stamen or carpel.
And finally, we find flowers consisting of a single stamen with a bract.
The function of the stamen is the development and distribution of the pollen.
C, Calyx; p, petal; e, stamen; s, stigmas.
- Stamen of Lady's Mantle (Alchemilla), with the anther opening transversely.
It sometimes happens that a single stamen is longer than all the rest.
Suppression of the anterior stamen sometimes occurs (e.g.
The pollen-bearer or stamen and the ovule-bearer or car pel.
- Stamen, consisting of a filament (stalk) f and an anther a, containing the pollen p, which is discharged through slits in the two lobes of the anther.
The number of stamens is indicated by the Greek numerals prefixed to the term androus; thus a flower with one stamen is monandrous, with two, three, four, five, six or many stamens, di-, tri-, tetr-, pent-, hexor polyandrous, respectively.
Young stamen is abortive, flower in which the stigma (N) is receptive and cannot perform and the stamens (3) have not yet opened; its functions.
In Scrophularia the fifth stamen appears in the form of a scale; and in many Pentstemons it is reduced to a filament with hairs or a shrivelled membrane at the apex.
- The stamen of the Barberry (Berberis vulgaris), showing one of the valves of the anther (v) curved upwards, bearing the pollen on its inner surface.
- Stamen of Asclepias, showing filament f, anther a, and appendages p. Enlarged.
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 Scrophularia the fifth stamen appears as a scale-like body; in other Scrophulariaceae, as in Pentstemon, it assumes the form of a filament, with hairs at its apex in place of an anther.
- Stamen of a species of Nightshade (Solanum), showing the divergence of the anther-lobes at the base, and the dehiscence by pores at the apex.
For when the older morphologists spoke of a stamen as a metamorphosed leaf, it was implied that it originated as a foliage-leaf and subsequently became a stamen.
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.
The phylogeny of the various floral leaves, for instance, was generally traced as follows: foliage-leaf, bract, sepal, petal, stamen and carpel (sporophylls)in accordance with what Goethe termed ascending metamorphosis.
E, Spur of the label e, The fertile stamen, with lum.
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.
(For further details on the form and arrangement of the flower and its parts, see Flower.) Each stamen generally bears four pollen-sacs (microsporangia) which are associated to form the anther, and carried up on a stalk or filament.
As a matter of fact, a stamen is a stamen and nothing else, from the very beginning.