AP BIOLOGY

Detailed explanation-1: -The first nonvascular plants to evolve were the liverworts . The hornworts evolved somewhat later, and mosses apparently evolved last. Of all the bryophytes, mosses are most similar to vascular plants.

Detailed explanation-2: -Pteridophytes were the first group of plants to have developed the vascular tissues.

Detailed explanation-3: -Nonvascular Plants. Nonvascular plants (often referred to collectively as the bryophytes) include three groups: the mosses (Bryophyta), approximately 15, 000 species; liverworts (Hepaticophyta), approximately 7500 species; and hornworts (Anthocerophyta), approximately 250 species (Table 1).

Detailed explanation-4: -The first land plants appeared around 470 million years ago, during the Ordovician period, when life was diversifying rapidly. They were non-vascular plants, like mosses and liverworts, that didn’t have deep roots.

Detailed explanation-5: -The first vascular plants evolved about 420 million years ago. They probably evolved from moss-like bryophyte ancestors, but they had a l ife cycle dominated by the diploid sporophyte generation. As they continued to evolve, early vascular plants became more plant-like in other ways a s well .