=6. Fraxinus quadrangulàta= Michaux. Blue Ash. Plate 129. Medium to large sized trees with light gray bark, not regularly fissured, scaly at least above; twigs and branchlets more or less distinctly 4-angled, the angles of vigorous shoots develop corky wings about 2 mm. high; leaves generally 2-3 dm. long; leaflets 7-11, generally 7-15 cm. long, on short stalks, usually 1-5 mm. long, sometimes sessile, the terminal one on a stalk generally about 1-2 cm. long, leaflets ovate to lanceolate, narrowed or rounded at the base, generally long acuminate at the apex, margins rather regularly and coarsely serrated with short incurved teeth, yellow-green and smooth above, about the same color beneath and generally smooth except along the veins, midrib and petiolules which are permanently pubescent; calyx very small, usually about 0.5 mm. long, and persisting more or less in fruit; fruit ripens last of June to August, samaras twisted, generally 3-4 cm. long and 8-10 mm. wide, rounded at the base, notched or rounded and apiculate at the apex, the apical end of all specimens at hand twisted to the right, the wing surrounds the body. =Distribution.=--Southern Ontario to Iowa, and south to northern Alabama and Arkansas. Found sparingly in most parts of Indiana, except the northwest part. There are no records northwest of White and Noble Counties. In the northern two-thirds of the State it is a rare to very rare tree, generally found only along the bluffs of streams. In many areas it is so rare that even the pioneers do not know the tree. It was the most frequent in the southeastern part of the State. Here also it is found principally along the higher banks of streams. While the species is confined principally to high ground it also grew in lower ground. The largest tree seen is on level ground at a fork of the road between Charlestown and Jeffersonville about 3 miles northeast of Jeffersonville. In 1918 this tree measured 28.2 dm. (104-1/2 inches) in circumference breast high. [Illustration: Plate 129. FRAXINUS QUADRANGULATA Michaux. Blue Ash. (× 1/2.)] This species has not been observed in the "knob" area of the State or anywhere in the flats of the Lower Wabash Valley. Schneck reports it as rare on the hills of this area. The tree is too rare to definitely determine its associates, although sugar maple is usually found with it. =Remarks.=--This species is becoming too scarce to be of much economic importance. The cut is usually sold as white ash. The uses of the wood are practically the same as the white ash. The fruit and foliage of this species most closely resembles that of the black ash, from which it can be distinguished by its greenish-yellow foliage and the habitat in which it grows.