During March and April, when the ground is thawing and the sap is flowing, holes are drilled into the sapwood at the base of the trunk. The watery sap drips down the spile and into the bucket. The sap is boiled down until it reaches the desired consistency for maple syrup. They are usually colored and flavored with caramel color and natural or artificial maple flavoring. They often appear darker and thicker than pure maple syrup.
Maple sugar comes from the evaporated maple syrup.
A recent article in Science Vol. They appear to be a very sophisticated system for regulating and conducting water to specific areas of the plant that need water the most. The pits are lined with a pit membrane composed of cellulose and pectins. According to the researchers, this control of water movement may involve pectin hydrogels which serve to glue adjacent cell walls together. One of the properties of polysaccharide hydrogels is to swell or shrink due to imbibition.