Salient features of Angiosperms

Angiosperms show several defining features that set them apart from every other plant group covered in this chapter. Their vascular tissue (xylem and phloem) is well developed. They produce flowers rather than cones as their reproductive structures. The embryo sac (ovule) stays enclosed within the ovary at all times, rather than being exposed. A pollen tube delivers the male nuclei directly to the egg, which means, unlike in bryophytes and pteridophytes, external water is no longer required for fertilization. Most distinctively, angiosperms show double fertilization — one male nucleus fertilizes the egg to form the zygote, and a second fuses with the polar nuclei to form a triploid endosperm, the nutritiv …