Though Cycas has an embryo with two cotyledons, it is not grouped under dicotyledonous plants, as:

The correct option is "ovules are naked".

To understand why Cycas is not classified as a dicotyledonous plant despite having an embryo with two cotyledons, let us break down the classification features step-by-step:

1. Fundamental Classification (Gymnosperms vs. Angiosperms):
Seed-bearing plants are majorly divided into Gymnosperms and Angiosperms. Gymnosperms (which include Cycas) are characterized by having naked seeds, meaning their ovules are not enclosed within an ovary wall. Angiosperms (flowering plants, which include dicots), on the other hand, have their ovules enclosed inside an ovary that later matures into a fruit.

2. Embryonic Features of Cycas:
Although the embryo of Cycas shows a transitionary or ancestral feature of having two cotyledons (resembling dicotyledons), it lacks the defining structures of angiosperms. It does not produce flowers or fruits, and its ovules are borne openly on the margins of megasporophylls without any protective ovary covering.

3. Conclusion:
In plant taxonomy, the presence or absence of an ovary enclosing the ovules is a more fundamental evolutionary distinction than the number of cotyledons. Because the ovules of Cycas are naked, it is grouped under Gymnosperms and cannot be classified as a dicotyledonous angiosperm.