=Remarks.=--The under surface of the leaves of the sugar maple in the northern part of its range are green, while those of the southern part of its range are quite glaucous beneath. To distinguish these two intergrading forms the southern form has been called =Acer saccharum= var. =glaucum= Sargent[61]. All of the trees seen in Indiana have leaves more or less glaucous beneath. This character, however, is not always evident in dried specimens. The writer prefers not to apply the varietal name to the forms of our area. The sugar maple always has been and will continue to be one of the most important trees of the State. In its mass distribution in Indiana it ranks not less than third. In the quality and uses of its wood it is equalled or exceeded only by the oak, ash and hickory. When compared with white oak it is a little lighter but thirty per cent stronger and fifty-three per cent stiffer. The greatest amount of the annual cut of maple is worked into flooring which is shipped to all parts of the world. It is much used in the manufacture of furniture and ranks third in use for veneer and hard wood distillation, and as a fuel wood is excelled only by hickory. Since pioneer times, the sap of this tree has been made into sirup and sugar and their manufacture now forms a valuable industry. On an average it takes 3 to 4 gallons of sap to make a pound of sugar, and an average sized tree will annually yield about 3 to 4 pounds of sugar. [Illustration: Plate 115. ACER SACCHARUM Marshall. Sugar Maple. (× 1/2.)] The sugar maple on account of its slow growth has not been used much in reforestation. It is very tolerant of shade, can adapt itself to almost all kinds of soils, thrives either in a pure or mixed stand, and is practically free from injury of insects and diseases. It has, however, been extensively used as a shade tree. For this purpose it is scarcely excelled by any other tree. When grown in the open it almost invariably assumes a symmetrical oval form, and the autumnal coloration of its foliage is rarely surpassed by any of our trees. Where a large tree is desired for street or ornamental planting the sugar maple can safely be recommended. =5a. Acer saccharum= variety =Rugélii= (Pax) Rehder. This variety of the sugar maple has leaves much wider than long, smaller and 3-lobed. The lobes are long acuminate and usually entire, sometimes the lower lobe has a small lobe near the base. This variety is included in our flora on the authority of C. S. Sargent who has given this name to specimens from Indiana in the writer's herbarium. The specimens so named are from the southern part of the State. While there is a wide range of difference in the shape of the leaves of the typical 5-lobed _Acer saccharum_ and its variety _Rugelii_, all intermediate forms can be easily found. The leaves of a tree will vary most on those trees whose average shaped leaves are farthest from the typical form.