The Garden Under Glass

356 THE GARDEN UNDER GLASS obliquely to the apex. The first illustration of Diagram 6, page 13, shows a sectional plan of a hip-roofed structure and gives a good idea of the form. Hung up.—A cutting is said to be hung up when its base does not rest on the soil beneath. This is caused by using a sharp-pointed dibber. By being out of contact with the soil, and having a cavity of air beneath, the cutting has very little chance of rooting. It is essential to successful propagation that the base of the cutting rests firmly on the soil beneath, and that the surrounding soil is made sufficiently firm to prevent the cutting from being easily pulled out. If pulled by the leaf, its leaf should break before a cutting which has been properly put in can be pulled out. Incurved.—A flower is said to be incurved when the petals fold over towards the centre of the flower. The incurved Chrysanthemum, which most readers will know, is a good example of this type. It is the direct reverse to reflex flowers, where all the petals point away Irom the centre of the flower. Larva.—The maggot stage in t he life of an insect, immediately following that of the egg and preceding that of the chrysalis. Many insects are injurious to plant life during the larva stage, notably the wire-worm and the vine weevil. A good illustration of the larva of the vine weevil is given on page 303, a. Lateral.—As the name implies, a lateral is a side growth springing from the main growth. Any further growths which spring from these laterals are termed sub-laterals. Layer.—A layer is a growth pegged into the soil for the purpose of forming roots, and eventually becoming a separate plant. Sometimes a cut is made to facilitate rooting, as in the case of carnations. In other cases this is not done, as in the case of a cucumber, when this form of propagation is adoptcd. The purpose of layering is to allow the intencled new plant to receive nourishment from the parent plant until it has formed sufficient roots to support itself, when the conncction between them may be severed. Propagation by layers is explained on page 212.