Page:TheTreesOfGreatBritainAndIreland vol01.djvu/172

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144
The Trees of Great Britain and Ireland
Scandica. Leaves with 7-9 pairs of nerves, lobes deep, with sharp teeth.
Minima. Leaves with 5-7 pairs of nerves, smaller and narrower than in the preceding varieties.
Certain forms of Pyrus pinnatifida closely resemble scandica, but the lobing in these will be found always irregular and often very deep.
15. Pyrus lanata, D. Don. Himalayas. Leaves large, broad oblong, woolly underneath, nerves 12-15 pairs, lobes regularly serrate.
C. Under surface of the leaves, which are orbicular in outline, snowy-white tomentose.
16. Pyrus Apia, Ehrhart, van flabellifolia. Greece. Leaves with 3-5 pairs of nerves.
17. Pyrus Aria, Ehrhart, var. græca. Greece, Asia Minor. Leaves with 6-10 pairs of nerves.

V. Leaves simple, not lobed, and only occasionally obscurely tabulate.

A. Aronia. Leaves finely serrate in margin, with glands on the upper surface of the midrib. This section comprises 2 North American species and a hybrid of garden origin, small shrubs, only referred to here to prevent their being confused with other species of Pyrus.
18. Pyrus arbutifolia, Linnæus fil. North America. Leaves beneath whitish grey tomentose, with about 6 pairs of nerves directed forwards at a very acute angle.
19. Pyrus alpina, Willdenow. A hybrid between Pyrus Aria and the preceding species. Leaves densely grey tomentose beneath, with 9-10 pairs of nerves directed outwards at an angle of 45°.
20. Pyrus nigra, Sargent. North America. Leaves glabrous beneath or very slightly pubescent.
B. Leaves without glands on the midrib.
(21-22) Leaves glabrous beneath. These 2 species, of which the first is a shrub and the other a small tree, are only referred to here to distinguish them from other species.
21. Pyrus Chamæmespilus, Linnæus. Vosges, Jura, Alps, Pyrenees. Leaves sessile or nearly so, elliptic, with 6-8 pairs of nerves.
22. Pyrus alnifolia, Franchet and Savatier. Japan and China. Leaves stalked, broadly ovate, with 9-12 pairs of nerves.
(23-26) Leaves white pubescent beneath.
23. Pyrus Aria, Ehrhart. Europe, Caucasus, Siberia, Central China. Leaves oval or elliptic with very slight lobules or only doubly-toothed, the teeth or lobules diminishing in size from above downwards; nerves 7-12 pairs, very prominent on the lower surface, pubescence snowy white.