I.] ROSACES. 153 



fruit an achene enclosed by the free calyx-tube] ; Straw- 

 berry [indefinite achenes upon a succulent rounded 

 receptacle] ; Blackberry and Raspberry [numerous 

 drupels\\ Meadow Sweet [several, about seven, follicles} ; 

 Rose [numerous free achenes enclosed in a concave suc- 

 culent calyx-tube or receptacle] ; and Apple [5 bony 

 carpels adnate to the calyx-tube]. 



The Natural Order Rosaceas furnishes our most 

 valuable orchard trees, as well as many of our most 

 beautiful garden flowers. 



Species affording useful fruits are Apple, Pear (Pyrus) ; 

 Quince (Cydonia); Medlar (Mespilus)-, Almond, Peach, 

 Nectarine (Amygdalus) ; Cherry, Apricot, Plum (Pruxus) ; 

 Loquat (Eriobotryd) ; Strawberry (Fragaria) ; Raspberry 

 and Blackberry (Rubus). 



Some of the Order, as Almond, Peach, and the species 

 of Primus^ contain prussic acid, the vapour of which, 

 given off from a crushed leaf of Garden Laurel (P. lauro- 

 cerasus) under an inverted tumbler, will soon destroy the 

 life of an insect. Owing to the presence of this acid, the 

 Oil of Bitter Almonds is a virulent poison. 



From the petals of sweet-scented species of Rose the 

 Attar or Otto of Rose is obtained. 100,000 Rose-flowers 

 are said to be required to yield three drachms of the 

 pure Attar.* It is consequently very costly, and is com- 

 monly adulterated with an Indian Grass Oil. 



Mossy galls, called Rose Bedeguars or ' Robin Red- 

 breast's Pincushions,' are frequent upon the Dog Rose 

 {Rosa canind) in autumn, produced by the puncture of 

 species of Cynips. If kept until the following spring, the 

 young Cynips will be produced, also species of Ichneumon, 

 which prey upon the Cynips. 



The fruit-bearing species in cultivation afford a good 

 opportunity of observing the different modes and effects 

 of grafting. To secure the success of a graft it is essen- 

 tial that the cambium-layers of the graft and stock should 

 be in contact, and the cut surface protected from evapora- 

 tion. A section through an old graft shows, notwith- 

 standing the complete union of the tissues of the graft 



* From 28 to 40 Ibs. of the petals in dry weather, or about 

 AlJf the quantity when moist, yield I drachm of Attar. 



