Conifers are predominantly trees, with needles or scale-like leaves, and range from very small species to the tallest trees on Earth -- redwoods, which exceed 300 feet in height. These plants grow scaled cones to reproduce.
The life cycle begins with a seed. Most conifer seeds possess a wing that carries the seed through the air to the ground. When the seed contacts the soil, the embryo inside germinates and sprouts.
Initially, the embryo grows using starches stored in the seed. Eventually, it sends out roots to obtain water and nutrients and a stem with leaves, becoming a seedling.
The seedling continues to grow, putting out more branches, leaves and roots. Once mature, it reproduces, growing cones made of overlapping scales.
Male cones generate pollen, from sex organs called microsporangium. Female cones produce ovules within their scales. The ovules contain mother cells called megaspores.
The megaspores form a megalogametophyte with an archegonium containing an egg cell. When pollen contacts the ovule, male reproductive cells fertilize the egg, which grows into an embryo. The megalogametophyte and embryo become a seed.
When the seeds mature, the female cone opens. Wind and gravity carry them away. If conditions are right, the seeds germinate to restart the life cycle.
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