There are two main classifications of seed-bearing plants in the world: the angiosperm and the gymnosperm. The main difference between the two lies in how the plants reproduce. An angiosperm is a flowering plant and disperses its seeds in fruit. A gymnosperm is a plant that does not have a true flower and does not disperse its seed in fruit. The absence of fruit and flowers is what makes a plant a gymnosperm.
Botanically, a fruit is a plant's ovary that has ripened. Fruits are often an incentive for animals to carry seeds to other locations. When the animal eats the fruit, it also eats the seeds and deposits them in a different location when it relieves itself. Not so with a gymnosperm. Gymnosperms often, though not always, rely on the wind to both fertilize and disperse its seeds.
The term "gymnosperm" literally means "naked seed" and refers to the fact that the seeds do not develop in fruits. One of the most recognizable types of gymnosperm is the conifer, which houses its seeds in cones. In order to reproduce, the male structure of the plant produces male cones that manufacture pollen. The pollen is then often dispersed by the wind to the female part of the plant. The seeds normally develop inside of a cone, and when ripe are dispersed when the scales of the cone open.
The seeds of this type of plant do not usually drop straight to the ground, however. If they did, the new plants would have to compete with their parents to survive. Rather, while the seeds are ripening, they develop "wings." This way, when the seeds are released, they can be carried by the wind to a new location. Once the seed sprouts, a new plant can grow in that location, continuing the species.
Most conifers are evergreens and have needle-like leaves. Some examples of conifers are spruces and firs. These types of gymnosperms are also among the oldest living things on earth. One type of spruce growing in Sweden was dated to be about 9550 years old. It has survived this long by adapting to a shrub or a tree, according to the climate where it lives.
Not all gymnosperms have needles, develop cones, and are evergreens, however. The ginkgo biloba (ginkgo) plant is a gymnosperm, but has broader leaves and seeds that look like fruits. In addition, it is deciduous, meaning it drops its leaves in fall. The plant is also unique because it is dioecious — that is, has separate male and female plants. Many other plants have both the male and female structures on the same plant.