How Does It Reproduce?

Blue spruce are monoecious meaning they have both male and female cones present on the same tree.  They undergo an alternation of generations with a dominant sporophyte generation.  Every two to three years full crops of cones are yielded.  Male cones are reddish purple and ripen to yellowish-brown.  They are found spread all over the tree.  Female cones are seed-bearing cones called strobilus, which are pale green and 6-11 cm in length.  They can produce up to 450 seeds and are found on the top 10-25 percent of the tree.

Seed production doesn’t begin until they are about 20 years old with optimum seed-bearing cones between the ages of 50 years and 150 years.  The seeds shed in September and continue shedding all winter.  Seeds germinate in spring or early summer.  Natural reproduction is sparse; possibly because the seeds lightweight prevents it from coming into contact with mineral soil, which, with an abundance of water and the right shade ratio is optimum for natural germination.   

Before they are able to germinate seeds must be fertilized.  To do this, microsporangium in  male cones produce hundreds of thousands grains of pollen through meiosis.  This pollen gets blown away in the wind and when it lands in an ovule next to female gametophyte fertilization can occur.  After fertilization a diploid cell grows into a zygote and develops into an embryo.  This embryo then develops into a seed, which eventually may fall to the ground and if the conditions are right it will grow into a new plant.

 

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