pls brifly tell why thallophyta,bryophyta and pteridophyta are classified as cryptogamae whereas gymnosperms and angiosperms are classified as phanerogams?

Cryptogams(cryptos-hidden, gamous-marriage) belong to thallophyta, bryophyta and pteridophyta. The reproductive organs in thallophyta, bryophyta and pteridophyta are hidden and are very inconspicuous. External flowers or seeds are not present.

Gymnosperms and angiosperms are the plant groups with well developed reproductive organs which produce seeds. These are called phanerogamae (phaneros-visible, gamous-marriage) as seeds are visible, The seeds may be naked (in gymnosperms) or enclosed in fruits (angiosperms).