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A mature female big-cone pine (Pinus coulteri) cone, the heaviest pine cone A young female cone on a Norway spruce (Picea abies) Immature male cones of Swiss pine (Pinus cembra) A conifer cone, or in formal botanical usage a strobilus, pl.: strobili, is a seed-bearing organ on gymnosperm plants, especially in conifers and cycads.
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The trees are mostly dioecious, with male and female cones found on separate trees, [4] though occasional individuals are monoecious or change sex with time. [5] The female cones, usually high on the top of the tree, are globose , and vary in size among species from 7 to 25 centimetres (3 to 10 in) in diameter.
The female cone then opens, releasing the seeds which grow to a young seedling. To fertilize the ovum, the male cone releases pollen that is carried in the wind to the female cone. This is pollination. (Male and female cones usually occur on the same plant.) The pollen fertilizes the female gamete (located in the female cone).
It is usually dioecious, with the male and female cones on separate trees, though occasional individuals bear cones of both sexes. The male (pollen) cones are oblong and cucumber-shaped, 4 cm ( 1 + 1 ⁄ 2 in) long at first, expanding to 8–12 cm (3– 4 + 1 ⁄ 2 in) long by 5–6 cm (2– 2 + 1 ⁄ 2 in) broad at pollen release.
The cones are squat globose, 10–12 cm (4–5 in) long and 12–14 cm (5–6 in) diameter, and take about 18 months to mature. They disintegrate at maturity to release the nut-like edible seeds. The seeds have a length of 2.5 to 3 cm (1.0 to 1.2 in) and a diameter of about 1.2 cm (0.5 in) with wide wings. There are four cotyledons present.
The female (seed) cones mature in about 20 months from pollination; when mature, they are yellow-brown in color, 15–25 cm (6– 9 + 3 ⁄ 4 in) long, and 5–7 cm (2– 2 + 3 ⁄ 4 in) broad, opening to 12 cm (4 + 3 ⁄ 4 in), and have a small, but sharp, downward-pointing spine on the middle of each scale.
The leaves are spirally arranged, very small and scale-like, 1 to 3 mm (0.039 to 0.118 in) long, covering the shoots completely. It is dioecious, with male and female cones on separate plants. The male cones are yellow, 5 to 8 mm (0.20 to 0.31 in) long and 1 to 2 mm (0.039 to 0.079 in) broad.