As the insect retreats from the flower, one or both of the pollinia are withdrawn, as at B.
In either case the change of position in the pollinia would insure the same result.
We begin with the fact, proved experimentally by Mr. Darwin, that moths do visit Orchids, do thrust their spiral trunks into the nectaries, and do fertilize them by carrying the pollinia of one flower to the stigma of another.
In Asclepiadaceae thepollinia are usually united in pairs (fig.
The number of pollinia varies; thus, in Orchis there are usually two, in Cattleya four, and in Laelia eight.
The pollinia are also provided with an appendicular staminal covering (fig.
The two pollinia in Orchis Morio contain each about 200 secondary smaller masses.
The pollinia are by this means transported by insects from one flower to the stigma of another.
Lord Farrer's observations on the movement of the pollinia in Ophrys muscifera are given.
Mr. More's observations on the percentage of flowers in which the pollinia were absent are quoted in "Fertilisation of Orchids," Edition I.
Does it not strike you as very difficult to understand how insects remove the pollinia and carry them to the stigmas?
This reminds me that I carefully described to Huxley the shooting out of the pollinia in Catasetum, and received for an answer, "Do you really think that I can believe all that!
I find that the pollinia do not move if kept in a very damp atmosphere under a glass; so that it is just possible, though very improbable, that I may have observed them during a very damp day.
He has seen lots of great humble-bees buzzing about the flowers with the pollinia sticking to their backs!
Since publishing, my son and myself have watched the plant and seen the pollinia removed, and where do you think they invariably adhere in dozens of specimens?
Will you have the kindness to look occasionally at your bee-Ophrys near Torquay, and see whether pollinia are ever removed?
When I first examined them I remember telling Hooker that moths would, I felt sure, fertilise them in a different manner; and I have just had proof of this in a moth sent me with the pollinia (which can be easily recognised) of H.
But if the bee went into the next flower with these pollinia sticking upright, she would simply put them into the same slits in the next flower, she would not touch them against the stigma.
Pollinia (at least sometimes) only 1 in each cell.
Pollinia granular or powdery, more or less cohering in 2 or 4 delicate masses, and attached at the apex to the beak of the stigma.
Pollinia 2, of coarse grains united by an elastic web, each attached at base by a stalk to a viscid gland.
Anthers with short if any scarious tip, borne on the margin of or close under the disk of the stigma; pollinia horizontal.
Anthers tipped with an inflexed or sometimes erect scarious membrane, the cells lower than the top of the stigma; pollinia suspended.
The firmness with which the pollinia keep their hold on the insect is one of the best adaptations for cross-fertilization.
So many orchids fasten their pollinia upon the faces and tongues of insects that it is interesting to find one which applies them regularly to the first abdominal segment.
If you are rarely skilful, you may induce your fly to withdraw the pollinia from all five slots on as many of his feet.
An Halictus repeatedly pulled down the labella (lips) of flowers from which pollinia had not been removed; and the only reason I can assign for its failure to extract pollinia is that it is more hairy than the Augochlora.
You may now invite the fly to take a walk on another flower in which he will probably leave one or more pollinia in its stigmatic cavities.
The hawk-moth removes on its tongue one, but not often both, of the pollinia attached to disks on either side of the entrance to the spur.
As a rule, Diptera (flies) either do not transfer pollinia at all, or become hopelessly entangled when they do.
The anthers have only rudimentary pollinia and do not open; there are no antennae, but on the other hand numerous seeds are produced.
The pollen, or more correctly, the pollen-tetrads, remain fastened together as club-shaped pollinia usually borne on a slender pedicel.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "pollinia" in a variety of sentences. We hope that you will now be able to make sentences using this word.
