This section is from the book "Woody Plants In Winter", by Earl L. Core, Nelle P. Ammons. Also available from Amazon: Woody Plants in Winter.
Deciduous shrubs or medium-sized trees. Twigs moderate, round or slightly angled, sometimes ending in sharp points; pith somewhat angled, continuous. Buds moderate, solitary, sessile, with about 4 scales. Leaf-scars alternate, linear; bundle-traces 3; stipule scars none.

Fig, 131. Pyrus communis.

Fig. 132. Pyrus malus.

Fig. 133. Pyrus coronaria.
a. | Twigs and buds glabrous; bud-scales submucronate, not margined; twigs olive | 1. | P. communis |
a. | Buds pubescent, their scales sometimes margined | ||
b. Buds blunt-ovoid; scales sub-obtuse; unarmed | 2. | P. malus | |
b. Buds conical-oblong; scales acute; and twigs sharp-pointed | 3. | P. coronaria |
1. P. communis L. Pear. Small tree, to about 15 m. high, when wild often with spinescent branches; branchlets olive,glabrous or giabrate, with inconspicuous lenticels. Introduced from Eurasia, spreading slightly from cultivation into thickets (Fig. 131).
2. P. malus L. Apple. (Malus pumila Mill.). A tree to 15 m. tall, with spreading branches, the trunk sometimes 1 m. in diameter; twigs more or less pubescent; buds blunt-ovoid, pubescent; scales more or less obtuse. Introduced from Eurasia, spreading and naturalized (Fig. 132).
3. P. coronaria L. Wild Crabapple.( Malus coronaria Mill.). Tree, somewhat armed (at least bearing sharp-pointed twigs), 6-10 m. high, the trunk 2. 5-3. 5 dm. in diameter; twigs glabrate; bundle-traces 3; buds conical-oblong, scales pubescent, acute. Thickets, New York and Ontario to Minnesota, south to Kansas and North Carolina (Fig. 133).
 
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