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INTRODUCTION TO BOTANY. XXxlll 
2. Accidental aberrations from the ordinary type, that is, those of 
which the cause is unknown. 
These require 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 species. 
Almost all species with coloured flowers are lable 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 produced 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. Spurs may disappear, or 
be produced on all, instead of only one of the petals. 
One part may be occasionally added to or subtracted from the usual 
number of parts in each floral whorl, more especially in regular, 
polypetalous flowers. 
The relative adhesion of the floral whorls may vary; hypogynous 
stamens appearing in flowers usually with perigynous, and 
free or half-free ovaries in flowers usually with adherent. 
Plants usually moncecious or dicecious 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. 
