ARBUTUS
- Arbutus, Linnæus, Gen. Pl. 123 (1737); Bentham et Hooker, Gen. Pl. ii. 581 (1876).
- Unedo, Hoffmannsegg et Link, Fl. Port. i. 415 (1809).
Evergreen trees or shrubs, belonging to the order Ericaceæ. Leaves simple, alternate, spirally arranged on the branchlets, coriaceous, persistent, stalked, pinnately-veined, entire or serrate, without stipules. Buds with spirally imbricated scales, within which the young leaves lie flat and are not rolled or folded. Flowers perfect, regular, in terminal compound racemes or panicles. Pedicel with two bracteoles, in the axil of an ovate bract; bracts and bracteoles scarious, persistent. Calyx five-lobed, free, persistent, unaltered at the base of the fruit. Corolla gamopetalous, hypogynous, urceolate or globose, with five obtuse, recurved, imbricated teeth. Stamens ten, included; filaments free, inserted on the base of the corolla, dilated and pilose at the base; anthers deflexed, dorsifixed, two-celled, opening by two pores, each anther with two awns on the back, against which insects knock in their search for honey and scatter the pollen through the pores. Pollen- grains united in tetrahedral masses of four grains each. Disc annular. Ovary superior, five- or occasionally four-celled; style columnar, stigmatose and obscurely five-lobed at the apex ; ovules numerous. Fruit a berry or drupe, the endocarp often being imperfectly developed. Seeds numerous, small, angled, with a coriaceous testa and a horny albumen.
About twenty species are known, inhabiting the western and south-western parts of North America, Central America, Ireland, the countries in Europe bordering upon the Mediterranean, the Canary Islands, Morocco, Algeria, Asia Minor, the Crimea, and the Caucasus. Many of the species are only shrubs or very small trees, and others are not hardy or have not been introduced. Only four species’ attaining a considerable size in cultivation in the open air in England, one of which is a hybrid, will be dealt with :—
A. Leaves serrate. Young branchlets glandular-pubescent.
1. Arbutus Unedo, Linnæus. Ireland, Southern Europe, Asia Minor, Morocco, and Algeria.
Leaves green beneath; petiole ¼ inch. Older branchlets dark brown, rough, and fissuring.
1 Arbutus canariensis, Lamarck, growing in the open air, is five feet high at Mount Usher in Wicklow ; but at Newry this species requires protection in winter.
Arbutus arizonica, Sargent, a native of the high mountains of Southern Arizona, if introduced, might be hardy.
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