Evolutionary history of plants phloem on the outside. Since xylem cells comprise dead, lignified tissue, subsequent rings of xylem are added to those already present, forming wood. The first plants to develop secondary growth and a woody habit, were apparently the ferns, and as early as the Middle Devonian one species, "Wattieza", had already reached heights of 8 m and a tree-like habit. Other clades did not take long to develop a tree-like stature. The Late Devonian "Archaeopteris", a precursor to gymnosperms which evolved from the trimerophytes, reached 30 m in height. The progymnosperms were the first plants to develop true wood, grown from
Naked yoga Naked yoga Naked yoga (Sanskrit "nagna yoga" or "vivastra yoga") is the practice of yoga without clothes. While many practice naked yoga at home and in nature, there are a growing number of participants in group classes. The practice is gaining popularity, notably in western societies that have more familiarity with social nudity. Naked yoga should be considered in relation to the dress code at yoga courses, varying from different times and yoga directions. Yoga has been practiced naked since ancient times. In the Bhagavata Purana it says: The practice of spiritual nudity is common among Digambara Jains, Aghori sadhus,