Narcissus and Daffodil

The biology of Narcissus 13
The flower stalk is a leafless single internode (or scape), which contains abundant
starch grains and raphides of calcium oxalate (Chan, 1952). The scape is topped
by a single flower or a cyme, the receptacle of which bends to bring the flower into
a horizontal position for anthesis and straightens after fertilisation to hold the
capsule upright, a tropic response to gravity accentuated by light. Flowers also
turn towards the light when growing in clumps (Rees, 1988). After flowers have
been picked, the lower part of the stem that is left behind is capable of considerable
growth from its basal meristem.
The flower bud is enclosed in a protective sheath or spathe, which is green during
bud development and dries and splits before anthesis. Flower development in
narcissus was described and reviewed by Huisman and Hartsema (1933) and Chan
(1952). The flower consists of two whorls of three perianth segments (or tepals)
which arise from a hypanthial tube, two whorls of three anthers, and a tricarpellate
inferior ovary with two rows of anatropous ovules in each of three loculi. The
corona (paracorolla, trumpet or cup), characteristic of the genus, is conspicuous
between the perianth segments and the anthers (Webb, 1980); it is regarded as
either a prolongation of the receptacle or as a distinct structure (Huisman and
Hartsema, 1933; Guédès, 1966). The floral parts are formed in a spiral sequence
from the perianth inwards to the gynoecium, although for horticultural purposes
the completion of flower initiation (important as a key stage in beginning cold
storage or hot-water treatment) is regarded as when the corona initial can be
clearly seen on dissection, following the initiation of the gynoecium (Huisman and
Hartsema, 1933; Cremer et al., 1974). There are many varieties with double flowers,
the structure of which varies in complexity (Reynolds and Tampion, 1983). Gross
flower abnormalities (such as two flowers from the same apex) are rare (Chan,
1952), although physiological disorders may occur in flower development (Rees,
1972). The floral biology of N. pseudonarcissus has been described in detail by Caldwell
and Wallace (1955). The corona and perianth tube lead to nectaries between
the staminal filaments, the flowers being pollinated by bumble bees (Bombus spp.).
Pollination is often poor due to a lack of insects in the relatively cool conditions,
and little pollination occurs in the absence of insects. Pollination of N. longispathus
in Spain was studied by Herrera (1995); the temperature inside the flower was up
to 8 °C above ambient temperatures, raising the temperature of pollinating bees
sufficient for flight. Di- and polymorphism with respect to style length has been
reported for N. tazetta and N. triandrus, respectively (Arroyo and Dafni, 1995; Barrett
et al., 1997). The fruits are ovoid green pods which grow to full size in about two
weeks and dehisce a few weeks later. The seeds are black and round and are
distributed over a restricted area; seeds of commercial narcissus cultivars were
described by Chan (1952).
Roots
The roots of narcissus are adventitious, unbranched, with a prominent root cap,
and are generally considered to have no root hairs, although a few poorly
developed root hairs can occur in some circumstances (Chan, 1952; Rees, 1972;
Kawa and De Hertogh, 1992). However, Chilvers and Daft (1981) found root hairs
in all cultivars examined, while Wilson and Peterson (1982) described the roots of
N. lobularis as initially glabrous and later with hairs. Price (1977) examined the