INTRODUCTION 
Iv 
III. Monocotyledones : Herbs, more rarely shrubby as in 
Dioscorea and Smilax or arboreous as in Palmce, Cordyline, Dra- 
ccena and some Bambusce. Stem destitute of central pith, not 
increasing in diameter by concentric layers of new tissues. Leaves 
usually parallel-veined, but net-veined in Smilax, Aracece and some 
others, usually not disarticulating freely from the branches. Paris 
of the perianth free or united, usually in threes or reduced to 
rudimentary organs and enclosed in chaff-like scales, as in the 
Gyperacece and Graminece. Ovule or ovules enclosed in an ovary. 
Embryo usually very small and embedded in abundant albumen ; 
cotyledon one, not easily distinguished before germination, and 
usually not appearing above ground in germination. 
Division 1. Petaloide,®. Perianth usually consisting of six 
coloured segments in two series. 
Subdivision 1. Infers. Ovary inferior. Orchidacece to 
Dioscoreacece. 
Subdivision 2. Supers. Ovary superior. Liliacece to 
Naiadacecs. 
Division 2. Glumifer^i. Perianth reduced to rudimentary 
organs enclosed in chaff-like bracts. Eriocaulacece to 
Graminece. 
Briefly summarised the Classification of Plants is into Classes, 
Divisions or Subclasses, Natural Orders, Genera, Species and 
Varieties. For example, the Marsh Marigold, p. 11, belongs to — 
Class : Dicotyledones. 
Division : Polypetalce. 
Subdivision : Thalamiflorce. 
Natural Order : Banunculacece. 
Genus : Galtha. 
Species : palustris. 
Varieties are distinguished by differences in the colour of the 
flowers and other minor characters. 
Exceptional Floral Structures 
It has been explained that a key to the Natural Orders to be 
useful must be elaborate. This is because there are so many 
exceptions to the general characters of some Orders ; and it is a 
key to the exceptions that is most needed by the beginner. I shall 
not attempt this, but a few words on the subject may be helpful. 
In the first place it should be understood that it is the sum of the 
characters that determines the place of a plant in the natural 
system, and not a conspicuous character that strikes the eye more 
than all the rest. Taking the Eanunculacese, for example, the 
