MR, J. G. baker's monograph OF BRITISH ROSES. 199 



canina, arvensis, and villosa) from those in which the prickles are 

 more abundantly developed and run down into aciculi by gradual 

 stages of transition (as in Sabini, rubiffinosa, and spinosissima) . 

 In the well-developed prickle in Rosa we may trace three types 

 of form : — the comparatively slender and nearly straight type, as 

 in mollissima and sjnnosissima \ the falcate type, which, besides 

 beiug decidedly hooked, is much more robust downwards than in 

 the last, and breaks offYrom the branch with a differently shaped 

 scar, as in canina and micrant1ia\ and, thirdly, the parrot's-beak 

 type, which is deltoid, with a short slightly hooked point, as in 

 stj/losa and arvensis. 



The nature of the fruit furnishes characters which are yery 

 useful for diagnostic purposes, only unfortunately they are to a 

 large extent lost in dried specimens. In the common Dog Eose 

 the sepals remain reflexed after the petals fall, and become dis- 

 articulated at the base before the hip becomes at all scarlet (this 

 IS what is meant by deciduous sepals); in tomentosa, ruhiginosa, 

 and Jiibernica the sepals ascend after the petals fall, and remain erect 

 npon the top of the hip till it changes colour, but become disarti- 

 culated before it fully ripens (this is what is meant by subpersis- 

 tent sepals) ; whilst in mollissima, involuta, and spinosissima the 

 sepals ascend in the same way and remain till the fruit is fully 

 ripe (this is what is meant hy persistent sepals). And between 

 the character of the sepals and the extent to which the disk 

 which closes in the top of the fruit is developed, and hairiness 

 and cohesion of the styles, there is a close correlation. The forms 

 that have persistent sepals have the fruit-disk hardly at all, or 

 not at all, developed, and the styles very hairy and not at all ag- 

 glutinated. The forms with subpersistent sepals, on the contrary, 

 have the disk always prominently developed, and the styles are 

 consequently crowded closer together and are much less hairy ; 

 and the development of the disk culminates in stylosa and arvensis, 

 m which, in combination with deciduous sepals, we have the 

 styles quite glabrous and united together in a prominent column. 



CI avis specierum*. 



Styles free, scarcely, if at all protruded beyond the top of the 

 calyx-tube. 



* Rare aberrant forms both here and in the diagnosis sometimes uut 

 taken into account. 



