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The female cone (megastrobilus, seed cone, or ovulate cone) contains ovules 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.
Pollen strobili of Pinophyta are similar to those of cycads (although much smaller) and Ginkgoes in that they are composed of microsporophylls with microsporangia on the abaxial surface. Seed cones of many conifers are compound strobili. The central stem produces bracts and in the axil of each bract is a cone scale. Morphologically the cone ...
Cupressaceae is a widely distributed conifer family, with a near-global range in all continents except for Antarctica, stretching from 70°N in arctic Norway (Juniperus communis) [3] to 55°S in southernmost Chile (Pilgerodendron uviferum), further south than any other conifer species. [4] Juniperus indica reaches 4930 m altitude in Tibet. [5]
The pollen cones are 5–6 mm (0.20–0.24 in) long, produced on long spikes in early spring; they are produced only on trees growing in regions with hot summers. The cones are globose to ovoid, 1.5–2.5 cm (0.59–0.98 in) in diameter with 16–28 scales arranged in opposite pairs in four rows, each pair at right angles to the adjacent pair ...
The male cones have structures called microsporangia that produce yellowish pollen through meiosis. Pollen is released and carried by the wind to female cones. Pollen grains from living pinophyte species produce pollen tubes, much like those of angiosperms.
Pollen tube elongation is an integral stage in the plant life cycle. The pollen tube acts as a conduit to transport the male gamete cells from the pollen grain—either from the stigma (in flowering plants) to the ovules at the base of the pistil or directly through ovule tissue in some gymnosperms.
The seed cones are globose to oblong, 20–40 mm long, with 6–14 scales, green at first, maturing brown about 20–24 months after pollination. The pollen cones are 3–5 mm long, and release their pollen in late winter or early spring. [8] [9] [10] The Latin specific epithet macrocarpa means "with large fruit". [11]
Ovulate cone Pollen cones, 2 cm scale bar. P. radiata is a coniferous evergreen tree growing to 15–30 m (50–100 ft) tall in the wild, but up to 60 m (200 ft) in cultivation in optimum conditions, with upward pointing branches and a rounded top.