30 THE COLOURS OF FLOWERS. 



of carpels is reduced to one. They have a succulent 

 fruit a drupe, the rr'ghest type and though the 

 flower contains two ovules, the ripe plum has only 

 one seed, the other having become abortive. All 

 these are marks of high evolution : indeed, in most 

 respects the Prunece stand at the very head of the rose 

 family ; but the petals are seldom very expanded, and 

 so, though they are usually deeply tinged with pink 

 in the cherry (Primus cerasus), and still more so in 

 larger exotic blossoms, like the almond, the peach, 

 and the nectarine, they seldom reach the stage of red. 

 Our own sloe (P. commums] has smallish white 

 flowers, as has also the Portugal laurel (P. lusi- 

 tanicus). In these plants, in fact, higher development 

 has not largely taken the direction of increased attrac- 

 tion for insect fertilizers; it has mainly concentrated 

 itself upon the fruit, and the devices for its dispersal 

 by birds or mammals. In the Rosecz, on the other 

 hand, though the fruit is less highly modified, the 

 methods for ensuring insect fertilisation are carried 

 much further. There are several carpels, -but they 

 are inclosed within the tube of the calyx, and the 

 petals are very much enlarged indeed, while in some 

 species the styles are united in a column. As regards 

 insect-attraction, indeed, the roses are the most ad- 

 vanced members of the family, and it is here, accord- 

 ingly, that we get the highest types of colouration. 

 Most of them are at least pink, and many are deep 

 red or crimson. Among the Pomea, we find an inter- 

 mediate type (as regards the flowers alone) between 

 Rosece and Prunece ; the petals are usually bigger and 

 pinker than those of the plums ; not so big or so pink 

 as those of the true roses. This interesting series 



