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A species of hybrid origin, occurring as a small tree, which may attain 50 feet in height, with smooth, grey bark. Leaves variable in shape, mostly pinnate or deeply cut at the base, with 1-4 pairs of segments more or less separate; the upper part cut into deep sharp-toothed lobes; green and glabrous above, grey tomentose below. Flowers white in loose corymbs; styles 3, woolly at the base; fruit small, globular, coral red, and resembling that of Pyrus Aucuparia.

This form, the parents of which are P. Aucuparia and P. intermedia, must be carefully distinguished (see p. 143) from Pyrus hybrida, Moench, a shrub of different origin.

Pyrus Thuringiaca, Ilse, a cross between P. Aucuparia and P. Aria, is generally included under P. pinnatifida, from which it differs only in the leaf, whiter beneath, having its upper part lobulate or dentate and not deeply lobed.

Sorbus arranensis, Hedlund, is the name given to a form occurring in the Isle of Arran, which is intermediate between P. pinnatifida and P. intermedia, and closely resembles the latter, differing only in the deeper and more irregular lobing of the leaf.

The hybrid forms, which are intermediate between P. pinnatifida and P. Aucuparia, are generally regarded as varieties (var. satureifolia and var. decurrens ) of the latter species, and will be mentioned in our account of the mountain ash.

Pyrus pinnatifida and the intermediate hybrids are variable and inconstant in the shape of the leaf There is no difficulty, however, in their identification, if it be noted that hybridity may be suspected in all cases where the leaves vary on the one hand from the regularly pinnate separate leaflets of Pyrus Aucuparia, and on the other from the regular uniform lobing or serration of Pyrus intermedia or Pyrus