With the vast majority of epiphytal orchids the old bulbs remain 

 to supply the plant with nourishment long after they have borne 

 their flower spikes. It is no uncommon sight to see imported plants 

 of Oncidium and Cattleya, particularly of C. pumila, showing a large 

 number of back bulbs, the smallest being in all probability the 

 second and third bulb that was made by the plant. In a rough sort 

 of way it is then possible to tell the age of these epiphytes. Bulbous 

 epiphytal orchids only draw on the back bulbs at special periods of 

 stress, such as during the dry season or when it is carrying its flower 

 spikes. Under cultivation and artificial conditions back bulbs cease 

 to he of use to a plant after four years, and generally turn black and 

 die. These must then be removed from the plant or they may affect 

 the other bulbs. Different genera act rather differently with their 

 back bulbs. Oncidium will keep several more back bulbs than an 

 Odontoglossum ; Cattleya, and Lalia are more vital in this respect. 

 Although an Oncidium may have seven back bulbs, it will not keep 

 leaves on all the seven years' growth. If it retains three years of 

 leaved bulbs it shows skilful cultivation, and more often two 

 years is the rule. In the wild state, while all the back bulbs do not 

 retain their leaves, yet they retain more than what one sees under 

 cultivation. It is a noteworthy fact that in Scotland orchid-growers 

 are able to keep their plants better leaved than in England, and it 

 may be due to the purer air. 



Before proceeding to general remarks on the cultivation, it will be 

 as well to state here that the usual cycle of an epiphytal orchid is to 

 start growing slowly with the appearance of the wet season, about 

 the month of March. During this early period the sustenance is 

 derived from the last-made bulb. After the growth has made some 

 headway (at about the end of April or early May in this country), it 

 begins to throw out wax-like green roots from the base of the growth, 

 and from this time onwards, while the roots grow the new growth 

 gradually supports itself. As the roots grow they become hardened 

 and of a whitish colour, but the tip for a varying distance of a quarter 

 to three quarters of an inch always remains green or yellowish- 

 green while the roots are growing. When the root action has 

 developed the new growth forms a bulb, or pseudo-bulb as it is 

 termed, in the centre, the two or three outermost leaves are thrust 

 aside, and the bulb itself carries one, two, or three leaves at its apex. 

 The flower spike is carried either at the side of the bulb (usually the 

 side with the longest leaf, but occasionally, if the plant is vigorous, 

 on both sides), or at the apex of the bulb, and when from the apex 

 frequently at first enveloped in a sheath. When the bulb is com- 

 pleted the plant ceases to be active, or, as it is called, rests, this 

 taking place in the dry season of its native habitats. Under 

 cultivation this resting period has to take place during our wet 

 weather, and the dryness which induces rest has to be created by 

 artificial heat. Some orchids flower after this period of rest, 

 and others before, that is to say immediately the new growth is 



