Narcissus and Daffodil

The biology of Narcissus 9
Table 1.1 The production of terminal (T) and lateral (L) bulb units in Narcissus a
Year 1 2 3 4 5 6 7
Bulb unit types T T T TT TTT TTTT TTTTT
L TL TTL TTTL TTTTL
LT TLT TTLT TTTLT
LTT TLTT TTLTT
LTL TLTL TTLTL
LTTT TLTTT
LTTL TLTTL
LTLT TLTLT
LTTTT
LTTTL
LTTLT
LTLTT
LTLTL
No. of bulb units 1 1 2 3 5 8 13
Increase over previous year – 1 2 1.5 1.7 1.6 1.6
Note
a After Rees (1969).
Figure 1.7 The growth pattern of terminal (T) and lateral (L) bulb units from initiation
to senescence, narcissus ‘Fortune’. The times of ‘scale’ initiation, floral initiation
and anthesis are indicated by 1, 2 and 3. (Modified from Rees (1969),
with permission of Academic Press Ltd.)
effect probably controlled by temperature; attempts to show a photoperiodic effect
were not successful (Rees, 1972).
In both terminal and lateral bulb units the full complement of bulb scales and
leaves is initiated during its first period of active growth, and the apices then
become inactive until the initiation of the flower at the end of the second period
of rapid growth of the terminal bulb unit, a year after the initiation of that unit