vi COLOURS OF PLANTS 897 



of cattle and wild herbivorous animals. Mr. J. P. Mansel 

 Weale also noticed that many plants growing in the stony 

 Karoo have their tuberous roots above the soil, and these so 

 perfectly resemble the stones among which they grow that, 

 when not in leaf, it is almost impossible to distinguish them 

 (Nature, vol. iii. p. 507). A few cases of what seems to be 

 protective mimicry have also been noted, the most curious 

 being that of three very rare British fungi, found by Mr. 

 Worthington Smith, each in company with common species 

 which they so closely resembled that only a minute examina- 

 tion could detect the difference. One of the common species 

 is stated in botanical works to be " bitter and nauseous," so 

 that it is not improbable that the rare kind may escape being 

 eaten by being mistaken for an uneatable species, though 

 itself palatable. Mr. Mansel Weale also mentions a labiate 

 plant, the Ajuga ophrydis, of South Africa, as strikingly 

 resembling an orchid. This may be a means of attracting 

 insects to fertilise the flower in the absence of sufficient nectar 

 or other attraction in the flower itself ; and the supposition is 

 rendered more probable by this being the only species of the 

 genus Ajuga in South Africa. Many other cases of resem- 

 blances between very distinct plants have been noticed as that 

 of some Euphorbias to Cacti; but these very rarely inhabit the 

 same country or locality, and it has not been proved that there 

 is in any of these cases the amount of inter-relation between 

 the species which is the essential feature of the protective 

 " mimicry " that occurs in the animal world. 



The different colours exhibited by the foliage of plants 

 and the changes it undergoes during growth and decay, 

 appear to be due to the general laws already sketched out, 

 and to have little if any relation to the special requirements 

 of each species. But flowers and fruits exhibit definite and 

 well-pronounced tints, often varying from species to species, 

 and more or less clearly related to the habits and functions of 

 the plant. With the few exceptions already pointed out, 

 these may be generally classed as attractive colours. 



Attractive Colours of Fruits 



The seeds of plants require to be dispersed so as to reach 

 places favourable for germination and growth. Some are 



