Shades of blue show climate divisions that had monthly average temperatures below 50Â°F. The darker the shade of blue, the lower the average temperature. Climate divisions shown in shades of orange and red had average temperatures above 50Â°F. The darker the shade of orange or red, the higher the average temperature.
A stroma is the connective, part of a cell, organ or tissue. The  function of a stroma is to hold the cell, organ, or tissue together  and help it maintain form. Edit.
The function of the guard cells are that they help to regulate the rate of transpiration by opening and closing the stomata thus preventing excessive water loss. The guard cell opens when there is too much water. It is also adapted for gas exchange between plants and environment.