INTRODUCTION TO BOTANY. XXXlll 



2. Accidental aberrations from the ordinary type, that is, those of 

 u'hich the cause is unknoxon. 



These requii-e the more attention, as they may sometimes lead the 

 beginner far astray in his search for the genus, whilst the 

 aberrations above reduced more or less to general laws, affect 

 chiefly the distinction of sisecies. 



Almost all species with coloured flowers are liable to occur occa- 

 sionally with white flowers. 



Many may be found, even in a wild state, with double flowers, that 

 is, with a multiplication of petals. 



Plants which have usually conspicuous petals will occasionally 

 appear without petals, either to the flowers j^roduced at par- 

 ticular seasons, or to all the flowers of particular plants ; or the 

 petals may be reduced to narrow slips, or variously cut. 



Flowers usually very irregular (81) may, on certain individuals, 

 lose more or less of their irregularity. Spui's may disappear, or 

 be produced on all, instead of only one of the petals. 



One part may be occasionally added to or subtracted fi-om the usual 

 nvmiber of parts in each floral whorl, more especially in i-egular, 

 poljqjetalous flowers. 



The relative adhesion of the floral whorls may vary ; hypogynou* 

 stamens appearing in flowers usually ^dth perigynous, and 

 free or half-free ovaries in flowers usually with adherent. 



Plants usually monoecious or dioecious may become occasionally 

 hermaphrodite, or hermaphrodite plants may produce occa- 

 sionally unisexual flowers by the abortion of the stamens or of 

 the pistils. 



Leaves alternate where they are usually opposite ; cut or divided 

 where usually entire ; variegated or spotted where usually of 

 one colour, or the reverse, — must also be classed among those 

 accidental aberrations which the botanist must always be on 

 his guard against mistaking for specific distinctions. 



