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
Bird food plants sour or aromatic fruits, distasteful to human beings, even better than the cultivated kinds. Many of these bird-attracting plants are ornamental as well, since many have pretty fruits, red in color and often clinging to their branches far into the winter, furnishing grateful additions to the meager fare of hard-weather birds. The many sparrows feed chiefly on weed seeds, but more acceptable plants from the gardener's point of view can be offered to them: Wild ducks are attracted by several aquatic and semi-aquatic plants, among the most important being: Bird food plants Bird food plants are certain trees, shrubs and