The Garden Under Glass

GLOSSARY This brief glossary is intended to explain the meaning of woids and expressions which, though familiær and commonpla.ce enough to gårdeners, are quite unintelligible to outsiders. It will be more convenient to treat the matter in alpliabetical order. Adventitious or aerial roots are those which spring from the stem of a tree or plant. They often occur on the grape vine, the tomato and liliums. Their presence is usually a sign that there is not sufficient nourishment in the soil, or the root-action is bad, though it may often also be ascribed to an excessive y humid atmosphere. When the roots occur on the rod of a_ grape vine it would be well to attend more closely to the ventilation The roots should not be cut off, but in the autumn they will usually rub off. The presence of such roots need not, however, cause any serious alarm. Aerial—Same as Adventitious. Air to a house, means to ventilate it. See page 261. Air Tap.—A small tap placed in the hot-water pipes at their highest point in the house, so that it may be opened to admit the escape of air which is likely to accumulate in the pipes and stop the circulation of heat. Sometimes an open lead pipe is attached to the pipes at this point and led up the roof of the house, so that the end is higher than the supply tank whch feeds the boiler. Personally, I much prefer a tap. Ihese taps should be examined periodically, especially so during winter, when the fire is being driven hard. ANNUAL.-An annual is a plant which grows and flowers from seed within a year and then dies. Anthracite.—This is a very hard dass of coal often used for greenhouse fires. It has the advantage of lastmg a long while 343