CLASSIFICATION 



marked off from each other. In this group are the Ferns, Club 

 Mosses, Horsetails. 



5. The Phanerogams. — This group includes all the plants which 

 flower and produce seeds, and have also w^ell-defined roots, stems, 

 and leaves. This group is divided into two distinct sections, viz. : — 

 (a) The Gymnosperms, or naked-seeded plants, in which the ovules 

 receive the pollen direct and are not enclosed in an ovary, as in 

 the Cycads and Conifers; and (h) The Angiosperms, or hidden- 

 seeded plants, in which the ovules are enclosed in ovaries, and the 

 pollen can only reach them by means of a tulie growing from 

 the pollen -grain through the tissues of the carpel or pistil in 

 the flower. 



All the plants described in this work are "Angiosperms." They 

 fall naturally into two distinct and easily recognised groups : — 



I. Monocotyledons. — These are plants in which the flowers 

 have their parts arranged in whorls or circles of three; in which 

 the embryo or baby plant in the seed has only one seed-leaf 

 or " cotyledon," and in which the main veins in the leaves are 

 usually parallel with each other or curvilinear. There are a few 

 exceptions, such as the Aroids and Yams {Dioscorea), which have 

 net-veined leaves. 



II. Dicotyledons. — These differ from the Monocotyledons in 

 having the parts of the flower arranged in whorls or circles of 

 four's or five's, the embryos have two seed-leaves or cotyledons, and 

 the leaves are net-veined. 



Another great distinction between Monocotyledons and Dicoty- 

 ledons: in the former the perennial woody stems do not increase 

 in diameter, owing to what are called the vascular bundles being 

 scattered and not being thickened by the growth of a " cambium." 

 In Dicotyledons the perennial woody stems have the vascular bundles 

 arranged in a ring, and by means of the circle of cambium layers 

 are enabled to increase in thickness year after year. 



It should be pointed out that in this volume no plants with 

 woody perennial stems are dealt with. All the bulbous, tuberous 

 and rhizomatous plants described are " herbaceous " {i.e. non-woody) 

 in character, and the aerial stems of a vast number, last only for 

 one season of growth — long enough to develop leaves, flowers, 

 and seeds — and then they die down naturally, leaving the basal 

 portion in a resting condition until the next season of growth. 



The following synopsis of the natural orders will enable the reader 

 interested in classification of plants to determine into which group 



43 



