Sweet-Sap Silver Maple
The Story of the Sweet-Sap Silver Maple
The Sweet Sap Silver Maple is a project that has been in the works since the 19600s. At that time, H. Cedric Larsson, a regional research forester with the Ontario Dept of Lands and Forests in Maple, Ontario, had found a cultivar of Acer saccharinum with a high sugar content in the sap. It tested somewhere around 3 to 5 % sugar content. He gave some root cuttings to his plant-breeder friends, one of whom was Fred L. Ashworth, the originator of St Lawrence Nurseries in northern NY state. Fred planted the cuttings and they quickly grew into trees. After Fred died in 1977, Bill MacKentley of Potsdam, NY, took over the nursery.
Our Sweet Sap Silver Maple is a special selection of Acer saccharinum that produces sap with a sugar content of 3 to 5%. (Sugar maples run about 2 to 2.5%.) The advantage to the syrup maker is less time collecting, hauling and boiling down sap. Silver maples will grow on wetter soils than sugar maples and they are much faster growers, becoming tappable in 8 to 10 years. They are also tolerant of clay soils. Discovered in Canada by Cedric Larson, and propagated via tissue culture. Maple syrup producers take note! There are a few suppliers promoting and selling seedlings of high-sugar parent trees. Although seedlings are important for their contribution to a diverse gene pool, they will not necessarily exhibit the high-sugar trait, since seedlings always involve genetic recombination. Only vegetative propagation (cuttings or micro-cuttings; tissue culture) will reliably produce the sweet sap trait in the offspring.
One of the sweet sap silver maples that Fred had planted was on the nursery property.
The problem was how to propagate this tree in a way that reliably yielded offspring with the same high-sugar sap. Seedlings would be quite variable. Root cuttings would not yield very many trees. Because of the interplay of root and stem in the yearly process of sap rising, grafting would probably not work, because the rootstock would exert an influence.
As tissue culture began to be successful with other species, Bill wondered whether the SSS maple could be propagated by this new method. He finally found a tissue culture lab that was able to propagate the sweet sap silver maple.
The importance of this cultivar is not as a replacement for sugar maple, but as an addition. Silver maples have more tolerance to wet and/or clayey soils. They can be planted on low lands that are not hospitable to sugar maple. They are fast growing, becoming tappable in 8 to 10 years. And this particular cultivar has a higher-than-average sugar content in the sap, which means less hauling and less boiling down.
Sweet Sap Silver Maple is sold at 4 to 6 ft. tall