Question

In Bentham and Hookers classification, the subclass Polypetalae and Gamopetalae have the cohorts in the ratio of
a. 1 : 1
b. 2 : 1
c. 2 : 3
d. 3 : 2

Answer 1

Hint: Bentham and Hookers are the group of plants which bear seeds. These are divided into three classes. Dicotyledons are further divided into three subclasses that are polypetalae, gamopetalae, and monochlamydeae. This series is further divided into order or cohort and order into family. It includes 6 cohorts. Polypetalae and gamopetalae have the same number of cohorts.

Complete answer:
The angiosperms are divided into two classes by Bentham and Hookers. In this classification gymnosperms are placed in between Dicotyledons. Polypetalae (corolla of distinct petals) series I thalamiflorae: petals and stamens are hypogynous. It includes 6 cohorts (orders) Ranales, Parietales, Polygalinae, Caryophyllinae, Guttiferalsm, malvales. Series II Discifore: petals and stamens hypogynous and a nectariferous disc. It contains the following cohorts: Geraniales, olacales, celastrales, Sapindales. In Series III Calyciflorae, petals and stamens are perigynous or sometimes epigynous. It includes 5 cohorts.

Gamepetalae(corolla of united petals): series I inferae: ovary inferior: it includes 3 cohorts that are Rubiales, Asterales, Camanales.

Petals are absent in Gamopetalae. Series I Curvembryeae have curved round the endosperm, only one ovule is absent.

From the above information we can say that in bentham and hooker's classification, the subclass polypetalae and gamopetalae have the cohorts in the ratio of 1 : 1.
Hence, the correct answer is option (A).

Note: Division of the orders makes the study and description of the species easier. Authors become models of accuracy. Order Ranales placed at the beginning of the system in this classification is very reasonable. Dicots are placed before monocots. Gymnosperms are placed in between Dicots and monocots which is a serious error. Monochlamydeae contains advanced primitive forms which is the drawback for this classification.