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Reproductive organs of trees are not always flowers. There are higher plants which do not have flowers and fruit but bear their seeds in cones or other structures instead - they are sometimes called gymnosperms. The biggest group within the gymnosperms are the conifers which include trees such as the pines (Pinus spp), redwoods (Sequoiadendron and Sequoia spp), juniper (Juniperus spp), yellowwoods (Podocarpus spp) and many more. In many of these trees e.g. the pines, the ovules (undeveloped seeds) are not contained inside a surrounding structure (the ovary) as in flowering trees but are borne on the bracts of cones instead. Others have berry-like structures e.g. juniper. The word Gymnosperm means naked-seeded and refers to the way the ovules are borne, i.e. exposed and not inside an ovary.

The pine

The pine is often used as an example of a typical non-flowering tree. Pines have "male" and "female" cones or more correctly pollen-bearing and ovulate cones. On the bracts of the pollen bearing cones, called microsporophylls, there are structures, the microsporangia  which contain the microspore mother cells from which the pollen will develop. On the bracts of the ovulate cones know as megasporophylls, the ovules are borne. The pollen must be transported from the pollen-bearing cones to the ovulate cones in order for fertilisation of the egg cell in the ovules to take place. The seed's embryo develops from the fertilised egg cell just as in flowering plants.

 

The ovulate cones of a pine tree

 

The pollen-bearing cone and ovulate cone of a pine tree showing the arrangement of the microsporangia and  ovules on the bracts of the cones .

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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