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Many Pinus species adapted to this fire-prone environment with serotinous pine cones. A set of conditions must be met in order for long-term seed storage to be evolutionarily viable for a plant: The plant must be phylogenetically able (pre-adapted) to develop the necessary reproductive structures; The seeds must remain viable until cued to release
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.
The wood is moderately hard and heavy, weak, light brown colour. The seed cones vary in shape, being rectangular to oval, cone shaped, straight or curved inward. [15] The cones are 3–5 cm (1 + 1 ⁄ 4 –2 in) long, the scales with a small, fragile prickle that usually wears off before maturity, leaving the cones smooth.
The female cones are large and usually woody, 2–60 centimetres (1–24 inches) long, with numerous spirally arranged scales, and two winged seeds on each scale. The male cones are small, 0.5–6 cm ( 1 ⁄ 4 – 2 + 1 ⁄ 4 in) long, and fall soon after pollination; pollen dispersal is by wind.
The seeds are large and heavy, 10 mm long and 8 mm broad, with a short rounded wing 13 mm long; [4] they may be bird or mammal dispersed as the wing is too small to be effective for wind dispersal. Trees start producing seeds at about 20 years of age.
The pine needles are in fascicles (bundles) of three, distinctively pale gray-green, sparse and drooping, and grow to 20–30 centimetres (8–12 in) in length. The seed cones are large and heavy, 12–35 cm ( 4 + 3 ⁄ 4 – 13 + 3 ⁄ 4 inches) in length and almost as wide as they are long.
The seed cones open to 6–9 cm (2 + 1 ⁄ 4 – 3 + 1 ⁄ 2 in) broad when mature, holding the seeds on the scales after opening. The seeds are 11–16 mm ( 7 ⁄ 16 – 5 ⁄ 8 in) long, with a thin shell, a white endosperm , and a vestigial 1–2 mm ( 1 ⁄ 32 – 3 ⁄ 32 in) wing.
In some cases, they will drop their seeds, but in most Pinus serotina, they will persist and hold their seeds. The color of the seed cones and seed scales is red-brown in color. The foliar sheaths measure 0.4 to 0.8 with long bases. The seeds are ovule in shape, being 0.2 and 0.24 in length, and have an angled tip colored a pale brown. [10]