Path-pointers. 75 



from below. But from what has been said concerning 

 Centaurea cyanus, it is plain that such down-turned 

 bristles may serve also as "path-pointers" toflyinginsects; 

 for these might occasionally creep up from the ground, 

 or, having first lighted on the leaves, might then try to 

 pass upwards to the flower along the stem. But the 

 parts which pre-eminently, and above aU others, act as 

 path-pointers are those upturned bracts which surround 

 the flowers and inflorescences of many Umbelliferse 

 {Eryngium aljpinum, etc.), as also the involucres of 

 many Compositse (Atractylis, Carduus, Kentrophyllum, 

 and innumerable other Cynarocephalae), with a dense 

 circlet of sharp points ; and again the prickles which 

 so often tip the sepals of the Labiates. It is by no 

 means uncommon to find one and the same involucre 

 with down-pointing prickles on its lower, and up-point- 

 ing prickles on its topmost, bracts ; an arrangement by 

 which defences are provided against visitors of the most 

 diverse kinds. This may be weU. seen in Centaurea 

 cyanus, and also in Garlina vulgaris ; the involucrum 

 of which latter, already referred to, is represented in 

 Plate I. fig. 20. 



Amongst these protective appliances, of which I 

 said above that they also act as " path-pointers," are 

 again to be reckoned those minute tooth-like pricklets 

 which are found on certain spots of the inner surface 

 of the perianth, as also on the androecium of some 

 Labiatse and Scrophulariacese. A very pretty example 



