Fertilization Of A Dendrobium Orchid Flower – Part One
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In the case of Dendrobium, such as Dendrobium nobile, the task, for an insect, is much simpler and less hazardous.
It will perhaps be interesting to see what happens after the dendrobium flower has been fertilized, either by an insect or by man in a greenhouse. After fertilization, and after a period of two days, the perianth (sepals and petals) fades and the upper part of the column starts to thicken and to become hemispherical in shape. Then after a further period of about three weeks, the pollen tubes begin to penetrate the ovary (which is just beneath the flower and appears to be part of the flower stem) in six strong bundles and to place themselves one on each side of the three placentas.
After a further three weeks, during which time the ovary together with the placentas have thickened and lengthened, these divide into two ridges each of which produces numerous minute papillae (small, fleshy projections) but there are, as yet, no ovules. After tow more months, however, the placentas are covered with numerous ovules with the pollen tubes still lying on each side of each placenta. After a further month or so, the ovules are fully developed and the ovary has reached its full size.
After roughly four months from pollination, the pollen tubes have entered the micropyle (a minute orifice in the ovule through which the pollen tube passes to fertilize the nucleus) and the process is nearing its end. A further fortnight sees the remaining pollen tubes complete their function and the ovary or, by now, the capsule will need only a further tow or three weeks to ripen.
Check out Fertilization Of A Dendrobium Orchid Flower – Part Two; the following facts refer to fertilization in a greenhouse after the pollen has been transferred by the agency of man (instead of a bee) and it must be considerably more rapid in nature.