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Pine Cones
A cone (in formal botanical usage: strobilus, plural strobili) is an organ on plants in the division Pinophyta (conifers) that contains the reproductive structures. The familiar woody cone is the seed-producing female cone. more...
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The male cones, which produce pollen, are usually herbaceous and much less conspicuous even at full maturity. The name "cone" derives from the fact that the shape in some species resembles a geometric cone.
The male cone (microstrobilus or pollen cone) is structurally similar across all conifers, differing only in small ways (mostly in scale arrangement) from species to species. Extending out from a central axis are microsporophylls (modified leaves). Under each microsporophyll is one or several microsporangia (pollen sacs). The photo (right) shows mature male pine cones shortly after pollen release.
The female cone (megastrobilus, seed cone, or ovulate cone) contains ovules within, which when fertilized by pollen, become seeds. The female cone structure varies more markedly between the different conifer families, and is often crucial for the identification of many species of conifers, in as much as seeing the foliage alone may be insufficient to differentiate between closely related species.
Female cones of the conifer families
Pinaceae cones
The members of the pine family (pines, spruces, firs, cedars, larches, etc) have cones that are imbricate with scales overlapping each other like fish-scales. These are the "archetypal" cone. The scales are spirally arranged in fibonacci number ratios.
The female cone has two types of scale, the bract scales, derived from a modified leaf, and the seed scales (or ovuliferous scales), one subtending each bract scale, derived from a highly modified branchlet. On the upper-side base of each seed scale are two ovules that develop into seeds after fertilisation by pollen grains. The bract scales develop first, and are conspicuous at the time of pollination; the seed scales develop later to enclose and protect the seeds, with the bract scales often not growing further. The scales open temporarily to receive pollen, then close during fertilisation and maturation, and then re-open again at maturity to allow the seed to escape. Maturation takes 6-8 months from pollination in most Pinaceae genera, but 12 months in cedars and 18-24 months (rarely more) in most pines. The cones open either by the seed scales flexing back when they dry out, or (in firs, cedars and golden larch) by the cones disintegrating with the seed scales falling off. The cones are conic, cylindrical or ovoid (egg-shaped), and small to very large, from 2-60 cm long and 1-20 cm broad.
Araucariaceae cones
Members of the Araucariaceae (Araucaria, Agathis, Wollemia) have the bract and seed scales fully fused, and have only one ovule on each scale. The cones are spherical or nearly so, and large to very large, 5-30 cm diameter, and mature in 18 months; at maturity, they disintegrate to release the seeds. In Agathis, the seeds are winged and separate readily from the seed scale, but in the other two genera, the seed is wingless and fused to the scale.
Read more at Wikipedia.org
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