162 Mr. Woods on the British Species of Rosa. 



liis having used the words aaileatiis, setosiis, and hispidi/s, as applied 

 to the fruit and peduncle; but he extends the difference no 

 further, and has given no explanation of the particular meaning 

 he attaches to these terms. 



Roses are furnished with aculei, setce, glands, hairs, chaff, and 

 jnibescence. Aculei or prickles are sometimes hooked, and gene- 

 rally more or less curved ; but in some species they are quite 

 straight. They have an expanded oblong base, and occur on the 

 stems, petioles and nerves of the leaves, and perhaps in one or 

 two instances on the fruit and fruit-stalk ; at least one variety of 

 R. spinosissima is either furnished with aculei, or with setae so strong 

 that they are very liable to be mistaken for aculei. 



Aculei are either straight, as in R. spinosissima ; straightish, 

 with a very slight curve downwards, as in R. villosa ; falcate, or 

 bent as a scythe, as in the large prickles of R. gracilis, and in 

 some varieties of R. tomcntosa; and hooked or uncinate, like a 

 claw or sickle, as in R. canina. Those of R. arvensis and of some 

 neighbouring species are frequently a sort of obtuse elliptical cone, 

 with a straight or curved mucro. This peculiarity of form is not 

 found in R. systyla, and is no where sufliciently constant to enter 

 into the character of any species. In the descriptions of the species, 

 the form of the aculei must be taken from those which grow on 

 the strong parts of the plant, and from those which are largest 

 and with the most extended base. 



SfiTiE are always straight, and tipped with a gland ; this gland 

 sometimes falls off, but vestiges of it can generally be perceived. 

 Seta3 are always smaller than aculei occupying the same situa- 

 tion ; that is, the setae of the stem are smaller than the aculei of 

 the stem ; the setae of the petioles are smaller than the aculei of 

 the petioles; but the setee of the stem are often larger than the 



aculei 



