518 GARDENING FOR BEGINNERS 



glass, or even frames for the housing of plants, that do not come under 

 the designation of span-roof or lean-to. Span-roof means a roof having 

 equal sides and sloping, so that a ridge runs through the centre. The 

 advantage derived by plants growing in a span-roof house is that they 

 have light all round them. The disadvantage of such houses is that, 

 having glass nearly all over them, they soon get cool, and thus need 

 ample fire heat. Span-roof houses may be tall and broad, such as are 

 large conservatories or vineries, or low and narrow, such as forcing 

 Melon or Cucumber houses. The path or alley affording access to the 

 house is in the centre. What is known as three-quarter span is a 

 house that has on one side a sloping roof of the usual half width of 

 the house, and on the other only a quarter of the house width, where it 

 meets a wall. There is no better or more common plant house than is 

 the full span-roof. 



Spawning. Gardeners use this term chiefly in relation to mush- 

 room culture. Mushroom spawn is purchased in the form of cakes of 

 dry soil and manure, which, whilst in a fresh or moist condition, has 

 been "spawned" to render them useful. Spawn is the fine thread- 

 like roots or, as usually called, Mycelium of the Mushroom fungus, 

 and the instrument of propagation. Small quantities of this root 

 mycelium are placed in the centres of the spawn cakes whilst yet 

 moist ; they are then stood in a warm place, with the object of in- 

 ducing this mycelium to spread through the cakes, after which the 

 cakes are stored for future use when dry. Spawning is done after a 

 bed of manure has been made up and has become warm, as then, if 

 each of these spawn cakes be broken up into several pieces and thrust 

 into the bed, the mycelium soon runs into the manure. Later on, 

 after the bed has been watered and coated over with soil, Mushrooms 

 come up thickly, as the result of the spawning. Spawn cake must be 

 made every year. If too old it becomes useless. 



Species. All vegetable life is divided into families, or genera^ as 

 the botanists say, and in each family there are many members or 

 " species." Thus every distinct member of any of these families is a 

 species, and has its specific as well as family name. Thus if the 

 Primrose family, which has members all over the world, be used for 

 illustration, we see them all classed botanically under the family name 

 of Primula. Now the common Primrose of our woods is Primula 

 vulgarity a distinct species. The Cowslip is P. veris, whilst the tender 

 Chinese Primrose is P. sinensis, or Chinese. There are scores of other 

 Primrose species. The secondary name given to species is usually 

 determined by its general character or place of growth. Thus Primula 

 minima is so called because it is so small, and P. marginata because 

 its leaves are margined with yellow, and so on. 



Spikes, Racemes. By the term " spikes " is meant a cluster of 

 flowers gathered on a single stem, long and somewhat pointed in form 

 rather than rounded, as in a truss. Hollyhocks, Snapdragons, Pen- 

 stemons, Veronicas, all have spikes, and in very pronounced form. 

 Spikes should be erect or stiff, and well held up by the stems on which 



