Gymnosperms

What are characteristics that unify gymnosperms? 
Gymnosperms literally means "naked seed". In gymnosperms a number of their leaves have evolved into scales. These scales are used in reproduction. Scales are grouped into larger structures called male and female cones. Fertilization is by pollen, not from mobile sperm.The female cones produce the eggs, while the male cones produce the pollen. Gymnosperms are the most ancient surviving seed plants.

This is a photo of the female and male cones. 

Below is a diagram showing the alternation of generations in gymnosperms. 

Gymnosperms have developed seeds that encase and protect their embryos. The dominant phase in the gymnosperm life cycle is the diploid (sporophyte) stage.

How do gymnosperm features aid in survival in a land environment? 

• Gymnosperm's roots extend over a wide surface area rather than penetrating deep into the soil. This feature lets them grow tall and holds the tree firm and provides a source of water and nutrients from the soil.
• Gymnosperm stems are used in the transport of nutrients throughout the plant.  
• Gymnosperms leaves are usually in the form of needles that stay green throughout the year.  Thin needle like leaves are an adaptation  to the harshness of hot, dry summer, cold winter and moderate rainfall.
• Gymnosperm seeds have protection and nourishment for developing embryo and can wait a long time to germinate when conditions are good.The seeds of gymnosperms are not enclosed within fruits. 
• In gymnosperms, the movement of pollen (male gamete) to ovule (female gamete) relies on airborne transport; No need for water to ensure fertilization. Most gymnosperms produce huge amounts of pollen. 
• Gymnosperm's vascular tissue, is extensive and makes up the bulk of the stem. This is what conducts water and nutrients up the body of the tree.