How many carpels in a banana

This is the seedless banana of commerce. Note the developing fruit and the cluster of unopened terminal bracts that hide developing male flowers. In the photo at the top right, the terminal bracts have been peeled back to reveal the functionally male flowers. The lower photo is a male flower. Note 5 functional yellow stamens. There is no stamen opposite the free inner perianth segment which is facing the camera in this photo. However, the cream colored style of the non-functional pistil is in view in the center of the flower.

Musa x paradisiaca , popo'ulu. This Hawaiian cultivar was used primarily for cooking. Musa paradisiaca ssp. There are three sepals and three petals Figure 4D. Two of the sepals and all of the petals are fused together, whereas one petal is free Figures 3A , 4B. It looks like flour. The pollen functions in plant reproduction, but the male banana flowers never form banana fruits. Female flowers have an ovary that develops into a banana fruit Figures 1 , 3 , but the stamens of female flowers do not make pollen.

The stamens are in two circles, with three stamens in the outer circle and two stamens in the inner circle. These five stamens are present in both male and female flowers Figure 3A , though they have no function in the female flowers. The female part of the flower has three sections. If you cut a banana crosswise, then you can often see these sections. You can even separate a banana into three long sections.

If you try this, then use a banana that is still a bit green. In both male and female flowers, the parts of the flower form in this order: two sepals form first, followed by a petal, then three stamens, the other two petals and stamens, and then the third and final sepal Figure 5. The ovary forms last and is formed in three sections Figure 6. As the first two sepals form, they change the shape of the young flower, so that it becomes triangular Figure 5C. The other flower parts form inside the sepals.

The first petal then appears Figure 5E , followed by the three outer stamens Figures 5F,G white arrows , then the two other petals and their closest stamens Figures 5H,I. The ovary forms last Figures 6A—D. In flowers like the banana, with the ovary below the other flower parts Figure 3A , the sections of the ovary form from the sides of a cup-like hole at the center of the flower Figures 5K,L , 6A—C.

While there are important differences between female and male flowers, both types of flowers produce their parts in similar ways. The differences that do occur do not result in differences between the mature flowers.

For example, in male flowers, the side of the flower that is next to the modified leaves Figure 4 , white arrowhead develops slightly ahead of the side that is away from these leaves Figure 4 , black arrowhead , whereas in female flowers, the opposite is true. These differences disappear by the time the female parts of the flower form, and are not visible in the mature flowers.

We have created an exercise that will help you better understand how banana flowers develop. This exercise is very similar to the way scientists study flower development. We can almost never watch a single flower develop over time because we have to destroy parts of the plant to see the young flowers. Although we cannot watch the development of a single flower, we can re-create this development by taking pictures of different young flowers and arranging the pictures in order.

We have taken the pictures for you. Now you have to arrange them in the correct order. Do not worry, we will give you some help. We will start with images that are similar to those used in this paper. Download and print the pictures in the file Musa velutina-Full size. These images came directly from a very powerful microscope called a scanning electron microscope. You will see that there is a small number on the lower left corner of each photograph. You will use these numbers to check your answer once you have placed the photographs in order.

Try it! If you find this task too difficult or if you want to check your work before looking at the key, then you can print a set of correctly sized photographs. The file Musa velutina-Resized. It will be easier for you to determine the correct order with these images because you can use size as a guide. However, be careful!

The size of a young flower is not always a perfect guide to its stage of development. Some of the photographs that look larger may actually show flowers at younger stages. When you are ready to check your work, print the file Musa velutina-Key. If your results do not agree with the key, you can try sorting the photographs again.

Scientists often arrange images like these many times before they are satisfied with the result. If you would like to continue your explorations, then you can download and work with the full set of photographs that were used in this research. There are photographs organized into folders based on the flowering branch they come from.

Follow this link to download all the photographs. Now that you have more experience looking at the stages of flower development, go back to Figure 5 and compare what you see there to your work, and to the key. The apparent, unbranched, errect and areal pseudostem is formed by the long, stiff and sheathy leaf bases which are rolled around one another to form an aerial pseudostem.

At the time of flowering, the shaft elongates, pierces through the pseudostem and produces an inflorescence terminally. The sheaths are nearly circular and tightly packed into non woody pseudostem which is functioning as the trunk of the plant. They are much longer than the blades. In general, shape of the blade is blunt at the tip and tapered, rounded or even auriculate at the base. It is thickest near the mid rid and thinnest at the margins.

The flowers are protected by large, brightly coloured, spirally arranged, boat shaped bracts called spathes. The flowers are polygamous i. The male flowers lie within the upper bracts, the female flowers within the lower bracts and the bisexual flowers within the middle bracts.