HORTICULTURAL SOCIETY OF NEW YORK. 



Epidendrums. In this case the thickened and shortened stem is referred to 

 as a pseudo-bulb. 



The inflorescence may be terminal or lateral, that is, it may arise from 

 the base or from the apex of the stem or pseudo-bulb. The stem may be 

 limited in growth, the case in most orchids, that is it may send out from the 

 main stem branches which never elongate, as in many of the epidendrons, 

 oncidiums and odontoglossums; or it may be of continuous growth, climb- 

 ing frequently to a considerable height on trees, the apex of the stem or its 

 branches continually advancing. To this latter group belong such genera 

 as Vanda, Angraecum, Vanilla, etc. 



The leaves in vernation are either conduplicate, that is folded, or they 

 are convolute or rolled. In the first case there is usually a marked midrib, 

 the rest of the leaf-frame being concealed in the fleshy tissue. In the second 

 case there are usually several longitudinal nerves, and the tissue of the leaf 

 is not so thick. 



The above elements in the structure of flower and body of the orchid 

 are used in their classification. It is not possible here, however, to go into 

 the details of this. 



The orchids are widely distributed, though mainly confined to tropical 

 and warm temperate regions. There are probably between 6,000 and 7,000 

 species at present known to science. In the Old World they reach their 

 maximum development in the East Indies and the Malayan region, while 

 in the New World they are found in the greatest abundance in northern 

 South America and in Central America. In the United States there are 

 perhaps 150 species, representing about 44 genera. 



The great mass of these plants is found in humid regions, although they 

 sometimes inhabit excessively dry areas. This latter condition was im- 

 pressed upon the speaker in a recent visit to the Inaguas, where he found 

 growing in juxtaposition many plants of several species of the genus Epi- 

 dendron and a species of Agave. The Inagus are xerophytic and desert con- 

 ditions prevail there. But the usual habitat is humid, either cold or hot, 

 where these plants may be found in great numbers on the trunks and 

 branches of trees, or sometimes clothing the faces of the rocks. Depending 

 largely for their water supply upon the moisture available on the trees, 

 a supply which must from the nature of things be more or less uncertain, 

 these plants usually have thickened stems or leaves, and sometimes both. 

 Whether you find them growing on trees in a humid forest or on the rocks 

 or shrubs in the desert islands of the Inaguas, the water supply is pre- 

 carious, and so in times of plenty the plants store up a water supply in the 

 thickened leaves or stems. While epiphytes, or those growing upon trees, 

 prevail in tropical and warm temperate regions, in cold areas, where frost 

 and cold become factors, the orchids are terrestrial, having underground 

 bulbs or fleshy roots which are protected by the surrounding soil. Adding 



25 



