762 THE SUBDIVISIOXS OF THE VEGETABLE KINGDOM. 



beyond 66° north latitude and 36° south latitude. Representatives of ViridiflorfB 

 are most abundant in the tropics. Fossil remains occur in the deposits of the 

 Mesozoic and Tertiary Periods. The presence of leaves of a Bread-fruit tree {Arto- 

 carpvs Dicksoni) in Greenland chalk, and of quantities of remains of Ulmaceae 

 (Celtis, Zelkova, Ulvius) in the Miocene strata, are points of special interest. The 

 number of species ascertained to exist at the present day is about 1000. 



Alliance XLIV. — Amentales. 



Families: BetulacecB, Corylacece, Gupuliferce, Juglandacece, Myricacece, Casuarinece, 



SalicacecB. 



Are all large shrubs and forest trees, forming a very conspicuous feature in the 

 landscape in temperate climates. The flowers are unisexual and arranged in 

 catkins or heads. Pollination is by wind, and, in the majority of cases, a perianth 

 is wanting. In the Cupuliferse, in which it is present, it is inconspicuous and con- 

 soKdated with the ovary. The group is an exceedingly interesting one, owing to 

 the recent discovery of several instances of chalazogamic fertilization within its 

 limits; of this, full details were given at p. 413. In this alliance are included such 

 familiar trees as the Birch {Betula, figs. 4^29 ^•-■^•*), Alder (Alnus, p. 135), Hazel 

 (Coryliis, p. 147), Hornbeam {Carpinus, p. 433 and figs. 429 ^•^•^•^), Oak {Quercus, 

 p. 298 and fig. 430), Beech (Fagus, fig. 431), Chestnut {Castanea, p. 445), Walnut 

 (Jicglans), Sweet-gale (Myrica), Casuarina, and the Willow (Salix, pp. 299 and 424) 

 and Poplar {Populus). Between 500 and 600 species have been distinguished. 

 Members of this alliance date far back amongst the secondary rocks, and they 

 are supposed by many to represent a primitive gi-oup of Angiosjjerms. 



Alliance XLV. — Balanophorales. 



Families: Hydnoracece, Sarcophytacece, CynomoriaceoB, BaUtnophoracece, 



Scybaliacece. 



Plants destitute of chlorophyll, parasitic on the roots of green-leaved woody 

 plants, with tubei'ous, cylindrical, or angular stems with flowering lateral branches. 

 The flowering axes are thickened and fleshy; the flowers hermaphrodite or pseudo- 

 hermaphrodite, moncecious or dicEcious. Perianth of 2-8 segments, sometimes 

 transformed into a cup on the top of the ovary, or absent and replaced by scaly 

 bracteoles and hairs. Gynseceum 1-3 carpellary; ovary inferior, unilocular, styles 

 either absent or 1-2 in number, filiform, and terminating in small stigmas. Stamens 

 1-60 inserted below the limb of the perianth. Fruit a kind of berry, nut, or drupe. 

 The embryo is very small, has no cotyledons, and is imbedded at the top of a fleshy, 

 oily endosperm. 



For a description of the suckers and scale-leaves, see vol. i. pp. 186-198. The 

 flowers of Hydnoraceae are solitary; those of Balanophoraceae, Cynomoriacese, and 

 Scybaliacese are crowded in large numbers on unbranched clavately-thickened axes, 



