Interaction between Plant Growth and Evergreen Seed Pouch

Plant Growth: https://www.aonprd.com/SpellDisplay.aspx?ItemName=Plant%20Growth

Evergreen Seed Pouch: https://www.aonprd.com/MagicWondrousDisplay.aspx?FinalName=Evergreen%20Seed%20Pouch

If a druid with an Evergreen Seed Pouch cast Plant Growth (the overgrowth version) while standing in the middle of a barren desert, what types of plants suddenly bloom in the desert? As a GM, would you allow the player to choose?

If so, would you allow them to cause plants not native to the area to spring into existence, such as creating a dense grove of pine trees, a flowering meadow or field of corn stalks?

If you would not allow the player/character to influence which plants are created, what would you describe the created tangle of plants as being composed of? Cacti? Palms? Tumbleweeds?

It seems to me that the plants created by this spell are entirely real, mundane and permanent (barring the effects of the local climate). Could a druid crossing a desert use this spell (in  conjunction with the ESP) to feed his pack animals, by conjuring dense patches of plants for them to graze on?  

What are your thoughts? Are there any other interesting interactions between this combination of magic item and spell?