The bulb is an underground shoot with leaves closely attached to the base. The structure of the bulb in different plants is the same, but may vary in shape, size. In their structure, all the bulbs are similar to the usual onions.
General structure
Considering the structure of the bulb in the section, it is clear that there is a bottom at the very bottom. Below it are the roots, and above - modified shoots. They accumulate nutrients during the dormant period.
Modified shoots include not only bulbs, but also rhizomes, tubers. Plants with rhizomes are irises, wheat grass, nettle. There are few tuberous plants; one of the most famous is potatoes. There are shoots underground under it, on the upper parts of which tubers grow. They have shortened internodes, do not contain chlorophyll. However, when the tubers are exposed and if they are exposed to direct sunlight for a short time, the tubers can turn green.
Looking at the structure of the bulb, you can see the embryos of the leaves. They accumulate a large amount of nutrients. They allow the leaves to move in growth at any time of the year. Therefore, it is onion plants that are used for early distillation, planting them in winter. This is their difference from other plants. Another difference is that the number of leaves is precisely determined in the bulbous, that is, the number of primordia is equal to the number of leaves.
In the lower part of the bulbs, near the bottom, are flower buds. How many buds are planted, so many flower shoots will grow.
When caring for onion plants, carefully pick off damaged and dried leaves, since if the buds are damaged, the leaf dies, and with severe damage the whole bulb can die.
In different plants, the flakes of the bulb adhere to each other in different ways. In lilies, they are not tight to each other, but there are plants with a snug fit, such as hyacinths.
Types of Bulbs
The internal, as well as the external structure of the bulb, is different for different types of plants. They are divided into the following subspecies:
- Film. Scales can cover completely the inside. The scaly edges touch. There are plants in which the scales can grow together.
- Half-tune. There are scales that never fuse.
- Tiled. The scales are very narrow. From one edge, they are in contact with neighboring scales.
- The number of scales in different plants is different. Some may have one, others three, five or more.
All scales are divided into:
Bottom scales grow, they make stocks of nutrients.
Tuber structure
The internal structure of the tuber and the bulb is different. On the outside of the tubers are sprouts - they are called eyes. There are more on the apical part than on the lower one. When landing in the ground from the eyes, the aerial part grows.
On the underside of the tubers are stolons. They receive nutrients. They accumulate in the shoots, then there is an active growth and thickening of the shoots, and by autumn tubers grow on the stolons.
The structure of the bulb and tuber is similar only in that they accumulate substances useful to the plant. Otherwise, they are different.
The structure of the rhizome
Rhizome is also an underground shoot of a modified type, which develops in perennials, shrubs. In it, as in the bulb, the nutrients necessary for the plant for normal development and maintenance of vital functions are stored.
The external structure of the rhizome of the bulb resembles an ordinary root, but differs in dissected internodes and scaly leaves on which axillary buds are formed . When the aerial parts die, a scar remains on the rhizome.
Rhizomes exist simple, thin, horizontal, thick, branched, vertical and ascending. These are far from all rhizome variants.
The life expectancy of the rhizome is an average of five years. In some plants, it can live for two years, and in some more than ten years.
Conclusion
Rhizome, tuber and bulb of plants are different types of altered shoots. They are similar in that they have short internodes, accumulate a large supply of trace elements and other nutrients. These plant organs do not contain chlorophyll.
Underground shoots are storerooms of vital substances. They contain starch, mineral elements, volatile. These parts of plants can be used as human food, as well as used as animal feed.