The older parts of the stem become woody, which provides a further distinction from the seedless vascular plants of which there are no surviving woody representatives. The wood of conifers is more primitive than that in angiosperm trees . It contains tracheids but no vessel elements, and there is generally less ray parenchyma in conifer wood than in dicot wood. Conifer life cycle Microspores and megaspores are formed on sporophylls in male and female cones respectively. Each scale in the male cone has two sporangia in which meiosis occurs to produce tetrads of spores, just as in a fern sporangium.
Mitotic divisions result in two prothallial cells, a tube cell and a generative cell.
The sporangium breaks open to shed the immature gametophytes which are carried on the wind and may chance to arrive at a sporophyll on a female cone. One megaspore develops into the female gametophyte which contains thousands of cells and is considerably larger than the male gametophyte. Male gametophyte development has to wait up to a year for the female gametophyte to mature and produce two or three archegonia with egg cells. The pollen tube grows slowly through a pore in the integument of the megasporangium and eventually the generative cell divides to produce two sperm cells. One of these fertilizes an egg cell to produce a zygote.