Orchids are unique in having the most highly developed of all blossoms, in which the usual male and female reproductive organs are fused in a single structure called the column. The column is designed so that a single pollination will fertilize hundreds of thousands, and in some cases millions, of seeds, so microscopic and light they are easily carried by the breeze. Surrounding the column are three sepals and three petals, sometimes easily recognizable as such, often distorted into gorgeous, weird, but always functional shapes. The most noticeable of the petals is called the labellum, or lip. It is often dramatically marked as an unmistakable landing strip to attract the specific insect the orchid has chosen as its pollinator. To lure their pollinators from afar, orchids use appropriately intriguing shapes, colors, and scents. At least 50 different aromatic compounds have been analyzed in the orchid family, each blended to attract one, or at most a few, species of insects or birds. Some orchids even change their scents to interest different insects at different times.

   Once the right insect has been attracted, some orchids present all sorts of one-way obstacle courses to make sure it does not leave until pollen has been accurately placed or removed. By such ingenious adaptations to specific pollinators, orchids have avoided the hazards of rampant crossbreeding in the wild, assuring the survival of species as discrete identities. At the same time they have made themselves irresistible to collectors.

The orchid is unique because of ........

Câu hỏi liên quan

• In the last paragraph, what does the author imply is a major function of hypotheses?

• The word “interfere” in paragraph 2 most nearly means ..........

• What does the writer mean by saying ''education quite often produces surprises"?

ZUNIA12

• The word “alarmingly” in paragraph 2 is closest in meaning to ____.

• The word "rough"in the passage  is closest in meaning to ...........

• The word "essential" in paragraph 1 is closest in meaning to .......

• Nowadays, there are ............

• According to the passage, the Eric Canal connected the .............

• The word “arrangement” in line 5 could best be replaced by which of the following?

• Which of the following would be the best title for this passage?

• The word “microbes” in paragraph 3 could best be replaced by which of the following?

• The word “benign” in paragraph 3 is closest in meaning to ________.

• According to the passage, biological agents mainly consist of ____________.

• According to the passage the first fire used by people was probably obtained .............

• Students who are not well – prepared to be young “adults” with all the responsibilities of life will need ______.

• The author believes that rote rotation is ........

• The word “they” in the last paragraph refers to ............

• The word “proliferated” is closest in meaning to ......

• The word "somewhat" in the last paragraph could best be replaced by ...........

• The Social Security program has become possible thanks to ______.