Question

How do Cycas and Adiantum resemble each other?

Answer 1

Adiantum is a pteridophyte while Cycas belongs to gymnosperms. Adiantum is also called maidenhair fern. Cycas belong to a class i.e. gymnosperms which literally means naked seeds.

Complete answer:
They both are similar in having motile sperms. True vessels are absent in both pteridophyta and gymnosperms while seed and cambium are only present in gymnosperms but absent in pteridophytes.
Pteridophytes are vascular plants that disperse spores as they do not produce flowers or seeds, they are also known as "cryptogams" because their means of reproduction is hidden. eg- Ferns, Horsetails.
The gymnosperms are seed-producing plants (eg- conifers, cycads, Ginkgo). Gymnosperms mean 'naked seeds' because of the unenclosed condition of their seeds.

Additional information:
Pteridophyte salient features:
1. They are the first true land plants.
2. Seedless but vascular cryptogams (hidden means of reproduction)
3. Heterologous diplohaplontic life cycle
4. Sporophyte consists of true roots, stems and leaves.
5. Gymnosperms salient features-
6. Do not produce flowers.
7. Naked seeds
8. Needle-like leaves are present.

Note:
Motile sperm can swim directly to the egg which is present inside the ovule. They need water for pollination so this mode is called hydrophilly. The male gametes should be produced in much larger quantities.