The conifers are Gymnosperms and, unlike the broad-leaved trees, their seeds are not enclosed in an ovary. As the name of the group implies, they bear cones. The pollen grains and ovules are always produced on different cones which usually occur on the same tree. Male cones. These are small and consist of a central axis bearing lateral scales which have two to five pollen sacs on their under surfaces. When mature the sacs split open and the dry powdery pollen grains are released. Female cones. At the time of pollination these are small and possess few to many complex scales attached to the central axis. On the upper surface of each scale there may be one (Monkey Puzzle), two (Pine) or several (Redwood) ovules.
Pollination. The pollen grains are carried by the wind and in most species come in direct contact with the ovules where they effect pollination and, sometimes much later, fertilization.
The seed-bearing cone. Subsequent development Is complex and may take place slowly. For example, in the Scots Ptne, 25 months elapse between pollination and seed dispersal. The familiar woody cones vary greatly in form and size according to species. In most the seeds are released when the scales bend back as they dry, but in Cedars and Firs the cones simply fall to pieces when mature; while In Juniper the fleshy scales remain closed so that the cone is like a berry. The seeds of conifers are often winged. They are always endospermic and the embryo usually has several cotyledons.
Note. The Maidenhair Tree and Yew do not have female cones and for this and other reasons they are usually put in a group separate from the conifers.
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