114 FAMILIAR TREES 



or " receptacular tube," which encloses the ovary with- 

 out adhering to it, in what is known technically as a 

 " perigynous " manner. The ovary itself consists of a 

 single carpel, terminated above in a well-developed 

 style and stigtna and enclosing two ovule's, one of 

 which only as a rule reaches maturity as a seed. The 

 " drupe," or " stone-fruit," which gives its name to the 

 Sub-order, consists of three fairly distinct layers, the 

 outer skin or " epicarp," the middle pulp or " meso- 

 carp " (which is commonly edible) and the inner 

 " stone " or " endocarp," enclosing the brown- skinned 

 kernel or seed, Lastly, many of the trees of the 

 group freely exude a very insoluble. gum, especially 

 where their bark is, injured; and the foliage and 

 kernels of the. entire Sub-order contain hydrocyanic, 

 commonly known as prussic, acid. 



The Peaches, Nectarines, Almonds, and Apricots 

 have woolly skins to the fruit ; the Cherry-laurels have 

 their flowers in racemes, their leaves " conduplicate " 

 (or folded together down the middle) in the bud, and 

 their fruits smooth and polished ; the Cherries have 

 their buds and fruits similar to the Cherry-laurels, but 

 their flowers generally otherwise arranged; whilst the 

 Plums proper, the genus Prunus in the more restricted 

 sense, have their leaves " convolute," or rolled up like 

 a scroll in the bud, and their fruits covered with a 

 glaucous " bloom " of wax. 



Botanists distinguish three varieties of the Com- 

 mon Plum {Prunus spinosa L.), though perhaps most 

 countryrfolk would assert the distinctness, even in a 

 wild state, of more than that number. When the 

 bark is black, the branches spreading in all directions, 



