Leaves flat, obtuse or emarginate at apex, with stomata only on the lower surface; cones ovoid, oblong or oblong-ovoid. Cones stalked. Cone-scales broad-obovate, about as wide as long, their bracts broad and truncate. 1. T. canadensis (A). Cone-scales narrow-oval, much longer than wide, their bracts obtusely pointed. 2. T. caroliniana (A). Cones sessile; cone-scales oval, often abruptly contracted near the middle, their bracts gradually narrowed to an obtuse point. 3. T. heterophylla (B, F, G). Leaves convex or keeled above, bluntly pointed, with stomata on both surfaces; cones oblong-cylindric, their scales oblong-obovate, longer than broad, much longer than their acuminate short-pointed bracts. 4. T. Mertensiana (B, F, G). 1. Tsuga canadensis Carr. Hemlock. [Illustration: Fig. 46] Leaves, rounded and rarely emarginate at apex, dark yellow-green, lustrous and obscurely grooved especially toward the base on the upper surface, marked on the lower surface by 5 or 6 rows of stomata on each side of the low broad midrib, ⅓′—⅔′ long, about 1/16′ wide, deciduous in their third season from dark orange-colored persistent bases. Flowers: male light yellow; female pale green, with broad bracts coarsely laciniate on the margins and shorter than their scales. Fruit on slender puberulous stalks often ¼′ long, ovoid, acute, ½′—¾′ long, with broad-obovate scales almost as wide as long, and broad truncate bracts slightly laciniate on the margins, opening and gradually losing their seeds during the winter and mostly persistent on the branches until the following spring; seeds 1/16′ long, usually with 2 or 3 large oil-vesicles, nearly half as long as their wings broad at the base and gradually tapering to the rounded apex.