Question

The primitive rhynia were widespread about how many years ago

400 million years ago

Answer 1

Answer:

Rhynia, one of the most common forms, was about 18 cm (about 7 inches) tall and possessed water-conducting cells called tracheids in its stem, much like those of most living plants. Underground runners connected its aboveground stems; these stems were photosynthetic, branched evenly many times,…