Broadleaved Trees

The broad-leaved trees illustrated on the following pages are Angiosperms, i.e. they bear flowers and the ovules are completely enclosed within an ovary. Further, as they are all Dicotyledons their leaves are net-veined and the embryo within the seed has two cotyledons. These features distinguish them from the other Angiosperm group, the Monocotyledons (including the Palms, not considered here) which have leaves with parallel veins and a seed embryo with a single cotyledon. There are, very roughly, about 160,000 known species of Dicotyledons grouped into some 260 families. The latter differ greatly in the number and habit of the species they contain. Some have few species which are all trees (Aceraceae), others are large and include herbs, shrubs and trees (Rosaceae) whilst other large families may be predominantly herbaceous yet still include a number of trees (Leguminosae).

It is obvious therefore that there are a great number of tree species and it is only possible to describe a selection in this book. The many tropical species are excluded but most of our native trees are mentioned and most of Ihe others are temperate species which grow well in Britain. Few introduced species are used in forestry but a large number are planted for ornamentation.

The key on the next two pages, which is based entirely on the features of the leaves, should help the reader to identify the commoner broad-leaved trees he sees. As most of the species are deciduous the key is best used during the growing season. The primary division is between simple and compound leaves and under both these headings the next separation depends on whether the leaves are opposite or alternate.

LEAVES SIMPLE ^

Pages

1. LEAVES ALTERNATE tQ^-CN

62-117

a) Blades not lobed or toothed, -y margins entire

Oiospyroa, Cercis, Madura, Magnolia

62-66

b) Blade toothed I) Fruit dry

Salix, Populus, Carpinus, Fagus, Betula, rr } Corylua, Castanea, Tilia, Atnus. Zelkova, / UlfTIUl (S

ii) Fruit more or less fleshy /

Celtic, Pruiius, Sorbus, Malua, Pyrus, Crataegus

67-89 90-104

c) Blade usually pirnately toothed or ..■■■"^■v, lobed, fruit borne in a woody cup

Quercus

105-113

d) Blade more or less palmately toothed or lobed

Llriodendron, Liquidambar, Platanos, Flctli

114-117

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Responses

  • sagramor
    What are broadleaved trees?
    6 years ago
  • Gilberto Genovese
    Are broadleaved trees angiosperms?
    6 years ago

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