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Various Contrivances Which Orchids Are Fertilised by Insects by Charles Darwin

Various Contrivances

Which Orchids Are Fertilised by Insects by Charles Darwin

Published September 12th 2013
ISBN : 9781230857602
Paperback
90 pages
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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1892 edition. Excerpt: ... to fly to anotherMoreThis historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1892 edition. Excerpt: ... to fly to another flower and occupy exactly the same position which it held whilst the attachment was effected, the pollen-masses would be in the right position for striking the stigma, especially if, from their weight, they were to become in the least degree depressed. This is all that takes place in Lyeaste skinnerii, Cymbidium giganteum, Zygopetalum maclcai, Angrsecum eburneum, Miltonia clowesii, in a Warrea, and, I believe, in Galeandra funhii. But if in our diagram we suppose, for instance, the stigma to be seated at the bottom of a deep cavity, low down in the column, or the anther to be seated higher up, or the pedicel of the rostellum to slope more upwards, &c.--all of which contingencies occur in various species, --in such cases, an insect with a pollinium attached to its head, if it flew to another flower, would not place the pollen-masses on the stigma, unless their position had become greatly changed after attachment. I may here remark that Del-dium, Epidendrum, Phaius, and pino ( Fecondazione nelle Piante, Dendrobium, and is able to con Firenze, 1867, p. 19) says he has firm in general my statements, examined flowers of Vanda, Onci This change is effected in many Vandeae in the same manner as is so general with the Ophreae, namely, by a movement of depression in the pollinium in the course of about half a minute after its removal from the rostellum. I have seen this movement conspicuously displayed, generally causing the pollinium to rotate through about a quarter of a circle, in several species of Oncidium, Odontoglossum, Brassia, Vanda, Aerides, Sarcanthus, Saccolabium, Acropera, and Maxillaria. In Rodriguezia suaveolens the movement of depression is remarkable from its extreme slowness- in Eulophia viridis from its...