GymnospermUploader: Nazahn 4 years ago Subscribe 3
A single microspore nucleus divides by mitosis to produce a few cells. Pteridosperm seeds were very similar to those of cycads and were often large, with a soft outer seed coat and a harder inner seed coat. Within each megasporangium , a single cell undergoes meiotic division to produce four haploid megaspores, three of which typically degenerate. Conifer leaves are always simple and often small and scalelike e. Facts matter and Britannica Insights makes it easier to find them. The growth tissue of the stem and branches, known as the vascular cambium, contributes more xylem each growing season , forming concentric growth rings in the wood.