The insects are attracted by various means. In addition to nectar, they are offered other types of nutrient tissue. In addition, the often overpowering fragrance and, of course, the mostly very striking colors of the flowers or individual parts of them serve this purpose. One of these mentioned lures is definitely represented and effective. Fragrance excretions from the flowers are coordinated with the flight time of the pollinating insect. In some Oncidium species, for example, they are oversized compared to the rest of the flower parts, mostly deep yellow lip is designed as a shining signal for insect eyes unmistakably clear. Many other examples could be given, to document the often sophisticated appearance of the plant, through which the pollination and subsequent fertilization, which are absolutely necessary for the conservation of the species, are to be ensured. The question arises, whether a lower expenditure of resources could not lead to the same result, as is the case with flowers of the usual type. Whether the complicated flower structure prevents self-pollination or the offspring is to be limited to a certain extent, may be an open question.
In the open flower, the ovary is initially not visible, as is the case with the tulip as an example already mentioned. In the case of the orchid blossom, it is preformed in the stem, initially, however, without ovules, which only develop after pollination has taken place. Then the pollen tubes grow slowly through the column into the ovary. The fertilization occurs weeks or months later, although the flower often wilts hours or a few days after pollination has taken place. However, the pericarp is only shed from the ovary after a long time or remains on the fruit until it is ripe. As a result of the long-term fertilization process, orchid fruits alone take a relatively long time to ripen. Apart from the climate-related short ripening time of native orchids, Dendrobium and Phalaenopsis need the shortest time of around 4 Months, Cattleya and Paphiopedilum, for example 10-12 Months and Vanda 15 Months.