Question

What is Cyathium? Give an example.

Answer 1

Hint: A flower that carries out reproductive activities of a plant is arranged and distributed over a stalk in a particular manner. Cyathium represents one of these arrangements, in which the flower is devoid of any accessory floral appendages.

Complete answer:
Cyathium is a special type of inflorescence that can be observed in Euphorbia species like Euphorbia pulcherrima. Here, the inflorescence itself looks like a single flower instead of a bunch of flowers arranged. The manner in which the flowers are arranged as well as distributed over a plant is known as inflorescence. The arrangement occurs on a peduncle which is the axis of inflorescence.
-A small conical receptacle i.e the part of the stalk to which floral parts are attached, is surrounded by involucre which may be five or six. The involucre is actually a whorl of bracts which protects or surrounds an inflorescence. They contain nectariferous glands i.e contain nectar.
-Internally, the inflorescence is composed of flowers that are naked i.e they are without any calyx or corolla. Such flowers are known as achlamydeous flowers and each of them possesses a stalk or are pedicellate. They are unisexual flowers with numerous male flowers on the periphery and a single centrally placed female flower.
-A male flower is represented by a single stamen and a pedicle. The male flowers are arranged centrifugally with younger at the perimeter and older in the core.

Note: -In a plant, the shoot apical meristem is transformed into a floral meristem and the leaves are specialized into floral appendages leading to the emergence of a flower. A typical flower is composed of 4 whorls or appendages organized successively on the thalamus or receptacle. The swollen end of the pedicel (stalk of a flower) is called the thalamus.
-The four whorls or appendages are- Calyx(sepals), Corolla(petals), Androecium(stamens), and Gynoecium (pistil or carpels). Calyx and corolla are accessory floral appendages while androecium and gynoecium are essential whorls.