Oftia 



( 128 ) 



Olax 



is saved. Offset production may be increased 

 artificially in some cases by scooping out the base 

 of an old bulb, and this is taken advantage of in 

 the case of Hyacinths which do not naturally give 

 many offsets. By various other means also is 

 offset production increased, as it has been found 

 that some injury to the growing point affects bulbs 

 somewhat as it does soft-wooded plants it 

 encourages basal shoots, and after all a bulbous 

 offset is only a basal shoot from a compressed 

 stem. 



OFTIA. 



Greenhouse evergreen shrubs (urd. MyoporineEe). 

 Propagation, by cuttings of young growths in sand, 



Vine Mildew, and it almost invariably follows a 

 chill induced by improper or excessive ventilation 

 in faulty houses. Vines are .subject to attack when- 

 ever the weather imposes a severe strain or check 

 upon growth. Chrysanthemums, Turnips, Grasses, 

 Peas, and Peaches, are all more or less subject to 

 mildews, but, fortunately, the attack is always 

 superficial, so that remedies, properly applied, will 

 generally relieve the plant infested, and prevent 

 serious damage. There are two methods of curing 

 these mildews ; one is by dusting the affected parts 

 with flowers of sulphur, and the other is by spray- 

 ing witli a weak potassium-sulphide solution, either 

 of which will kill the mycelium, and not injure the 

 host. 



CEXOTHERA SPECIOSA (see p. 127). 



beneath a bell-glass. Soil, loam, leaf mould, and 

 sand. 



Principal Species: 



africnna, 3', sum., wh. (syn. Spielmannia africana). 



OIDIUM. 



This genus of fungi is one with which every 

 gardener would rather not have any immediate ac- 

 quaintance. The various species are capable of doing 

 much damage to plant life, and appear as moulds, 

 or rather as mildews ; and wherever they settle 

 down to an attack their presence is made manifest 

 by a white, downy coating, consisting of a dense 

 mass of minute filaments, or mycelium, from 

 which in due course appear the tiny, cellular heads 

 that, under suitable conditions, extend the species. 

 O'idium Tuckeri is the fungus known all too well as 



Oijechec (see Nysm). 

 O/ngffimia (sec Hoffmanma). 



It is necessary to point out that although the 

 O'idiums are generally regarded as a distinct section 

 of fungi, and, indeed, may so be considered liorti- 

 culturally, yet each member is but a stage in the 

 life cycle of a fungus that may be an Erysiphe or 

 a Sphaerotheca, but which cannot be determined 

 until the perfect or fruiting stage is reached, and 

 it is the fact that this stage is only reached under 

 especially favourable circumstances that led to the 

 use of the title Oidium for species (then undeter- 

 mined) that had a mildew or Uidiuiu stage of 

 growth. 



OLAX. 



Stove evergreen climbers (ord. Olacinese). Prop- 

 agation, by cuttings of ripe growths in sandy peat, 



Oil Xttt (see Pijrularia oleifera). 

 Oil Palm (see Elieif). 



