748 THE SUBDIVISIONS OF THE VEGETABLE KINGDOM. 



antiquity; it grows in the Upper Nile, Syria, Palestine, &c. The stem of Papyrus 

 bears at the summit an umbel-like tuft of filamentous branches, upon which the 

 inflorescences arise. Cyperacese grow for the most part on damp moors, and by 

 the banks of streams and lakes, and in mountain regions. Many of them are social 

 forms, noteworthy in this respect being Carex stricta, which forms hummocks in 

 marshy places, standing up above the water, often thousands together. Several 

 Sedges, e.g. Carex sempervirens and C firma, contribute largely to the turfy carpet 

 of alpine slopes (c/. Plate XII.). 



Th-e family is distributed over the whole world. Carex, Eriophorwrn, and 

 Scirpus are found especially in cooler and northern zones; Cyperus and Papyrus in 

 warmer regions. About 2500 species are known. 



Class II.— DICOTYLEDONES. 



Flowering Plants whose flowers typically have their parts arranged in whorls 

 of four or five, embryos with two cotyledons, vascular bundles arranged in a ring 

 a,nd undergoing a secondary increase in thickness, leaves more complex than in 

 Monocotyledones and usually reticulately veined. 



The Dicotyledones may be divided into three Sub-classes: Monochlaraydece, 

 MonopetalcB, and Polypietalce. The Monochlamydese have a simple perianth, or in 

 some cases the perianth may be wanting. The Sub-class is an artificial one, as it 

 includes forms whose ancestors probably possessed a double perianth and others 

 which are primitively simple. The Monopetalae and Polypetalse possess both calyx 

 and corolla; in the former the parts of the corolla are united together, in the latter 

 free. 



Sub-class I. — M0NOCHLAMTDB.S). 



Alliance XXXV. — CentrospermsB. 



Families : Piperacece, Polygonacece, Cynocramhacece, Urticacece, Chenopodiacem, 

 Nyctaginacece, Amaranthacece, Paronychiacece, CaryophyllacecE. 



Annual or perennial herbs, shrubs, and trees. Venation of the leaf-blades 

 palmate or pinnate. Flowers solitary or in cymes; the cymes arranged in fascicles, 

 glomerules, or spikes. Flowers actinomorphic, hermaphrodite, pseudo-hermaphrodite, 

 monoecious, and dicEcious. Floral-leaves in one or two whorls; all sepaloid, all 

 petaloid, or (in a few cases) the outer whorl sepaloid and the inner whorl petaloid. 

 Where a corolla is developed the petals are free. In the case of dicEcious flowers 

 there is no diff'erence between the male and the female flowers in respect of the 

 development of floral-leaves. The ovary is superior; 1-5-carpellary, unilocular. 

 The ovules are borne in the centre of the ovary on a stalk which rises from the 

 bottom of the ovary, and is sometimes long, sometimes short. Stamens 1-30, arranged 

 in one or two whorls, the outer ones inserted in front of the sepals or sepaloid 

 perianth segments. Fruit an achene, capsule, or berry. The seed contains an 

 abundant farinaceous or mucilaginous endosperm. Cotyledons not thickened. 



