Poaceae have hollow stems called culms plugged at intervals by solid leaf-bearing nodes. Grass leaves are nearly always alternate and distichous (in one plane), and have parallel veins. Each leaf is differentiated into a lower sheath hugging the stem and a blade with entire (i.e., smooth) margins.oaceae have hollow stems called culms plugged at intervals by solid leaf-bearing nodes. Grass leaves are nearly always alternate and distichous (in one plane), and have parallel veins. Each leaf is differentiated into a lower sheath hugging the stem and a blade with entire (i.e., smooth) margins.
Air conditioning system components consisting of Condensing Unit, Evaporator Coil, Refrigerant line. How air conditioning works is kind of a mystery to many of us. Furnaces are easy to understand, they heat air and blow it around your home in ductwork.
Types of Systems. We've just described what is called a split system - the condensing unit is placed outside the house, and the evaporator coil is inside. There is another configuration called a packaged air conditioner that combines the condensing unit and the evaporator coil into one outdoor unit.entral air conditioning units are usually matched with a gas or oil furnace to provide heat through the same set of ducts. There are also central HVAC units called heat pumps that combine both the heating and cooling functions.