22 2 Flowers and their Pedigrees. 



unlike that of the blackthorn, and similarly armed 

 with stout spines, which are really short sharp 

 branches, not mere prickly hairs, as in the case of the 

 brambles. Occasionally, however, some of the haw- 

 thorns develop into real trees, with a single stumpy 

 trunk, though they never grow to more than mere 

 small spreading specimens of the arboreal type, quite 

 unlike the very tall and stateh- pear-tree. The 

 flowers of the hawthorn — may-blossom, as we gener- 

 ally call them — are still essentially of the rose type ; 

 but, instead of having a single embryo seed and 

 simple fruit in the centre, they have a compound 

 fruit, inclosing many seeds, and all embedded in the 

 thick fleshy cal}-x or flower-cup. As the haw ripens 

 the flower-cup outside grows redder and juicier, and 

 the seed pieces at the same time become hard and 

 bony. For it is a general principle of all edible 

 fruits that, while they are young and the seeds are 

 unripe, they remain green and sour, because then 

 they could only be losers if eaten by birds ; but as 

 the seeds ripen and become fit to germinate, the pulp 

 grows soft and sweet, and the skin assumes its bright 

 hue, because then the birds will be of service to it by 

 diffusing the mature seeds. How largely birds assist 

 in thus dispersing plants has verj' lately been proved 

 in Australia, where a new and troublesome weed has 



