I. INTRODUCTION 



MAINLY FOR NON-BOTANICAL READERS 



I AM frequently asked "What is an orchid?" As I hope that among my readers will 

 be some with httle botanical loiowledge, I wiU briefly mention the outstanding 

 pomts of diiference between orchids and other famHies of flowers. The popular 

 term "Orchid" includes all members of the great family Orchidace^e. Orchis, how- 

 ever, is a name belonging to one particular genus out of the 500 genera of the 

 Orchidace^. 



If you look at any ordinary flower you will see in the middle a number of stamens 

 consistmg of thread-like stalks (filaments) each with an anther at the top, which when 

 ripe emits a quantity of very fine usuaUy yeUow dust-like pollen. In some species 

 the anthers have no stalks, and are sessile. They vary in number from two in Veronica 

 to very many in St Jolin's Wort. In the centre of these there is a thicker stalk, called 

 a style, which is a prolongation of the ovary (seed-vessel), and is either sticky at the 

 top or covered with little protuberances (papillae), whose function is to retain any 

 poUen-dust brought to it by wind or insects. This rough or sticky area is caUed the 

 stigma. Sometimes it is on the top of the ovary without any style or styles. 



In the flower of an orchid there are no free stamens or styles. The filaments of 

 the stamens and the style are fused together to form a solid central body caUed the 

 column. This is the great distinguishing feature of the family Orchidaces. Also the 

 pollen IS never dusty, but consoHdated into masses called pollinia, except in the 

 Diandra;. Ground orchids, with which alone we have to do, there beinj? no tree 

 orchids m Europe, consist of two sub-families— so distinct that they would be con- 

 sidered separate families, but that both have the column in common. 



The first of these, the Diandrse, comprises only the Cypripediums and their allies 

 of which Cypripedium calceoks, the Lady's Slipper Orchid, with its yellow calceolaria-like 

 lip, IS our only British representative (PI. i). The Diandn^ have a branched column 

 ending in a large staminode, with only two anthers, each on a side branch of the 

 column, brimming over with a very sticky semi-Hquid paste in which the single 

 pollen-grams are embedded (PL A, fig. 4). The large stigma, which consists of three 

 stigmas jomed mto one, is on a branch of the column and faces downward. It is 

 dry and rough with papillae in our species. 



All the rest of our orchids belong to the sub-family Monandry, with only one 

 fertile (pollen-producing) anther at the summit of the column, with the stigma just 

 below It, recognisable by its glistening sticky surface. The pollen-grains are built up 



GBO 



