Question

Differentiate between Corymb and umbel.

Answer 1

Hint: Both the corymb and umbel are types of shortened-axis racemose inflorescence where the main axis continues to grow indefinitely and terminate in a flower.

Complete answer: Racemose inflorescence is also known as indefinite or indeterminate inflorescence and there are three types of it which are Elongated main-axis, Shortened main-axis and Flattened main-axis. Corymb and Umbel come under the shortened main-axis.
In this type of inflorescence, the growth of peduncle is indefinite and it continues to produce a flower bud and peduncle is monopodial.
Grouping of flowers is usually not that common in this inflorescence and when seen then groups of flowers are arranged centripetally which means that the younger flowers are in the middle and older flowers are seen at periphery.

Corymb	Umbel
1. The peduncle of corymb is well-developed.	1. The peduncle of the umbel is reduced to a point.
2. From the peduncle of corymb, flowers arise at different levels.	2. From the peduncle of the umbel, flowers arise from a common point.
3. As compared to pedicels of younger flowers, the pedicel of older flowers is much more elongated.	3. The Pedicles of younger and older flowers does not have much difference in their length.
4. Flower arrangement in corymb is acropetal.	4. Flower arrangement in the umbel is centripetal.
5. Bracts are present at a various levels which depend on origin of flowers and an involucre is always absent in it.	5. In the umbel, an involucre is present at the place of origin of flowers.
6. Example- Cauliflower	6. Example- Onion, Paper plant, coriander

Note:
The difference between both of these are that the peduncle of corymb is well-developed whereas the peduncle of umbel is reduced to a point, also the flowers in corymb arise at different levels where as in umbel, it arises from a common point.