Long-flowering bulbs
Jane McGary (Sun, 06 Apr 2014 11:09:07 PDT)

One reason why individual flowers remain in good condition for a long
time is that they are not being pollinated. As soon as fertilization
takes place, there is no need to attract more pollinators and the
flower's showy petals often wilt and dry out. I also notice that the
earliest-flowering Narcissus species here, such as Narcissus
cantabricus and Narcissus romieuxii, are very persistent this way,
but the later members of the same (Bulbocodium) section wither
sooner. I don't have the early ones in the open garden.

Continuous bloom with repeated production of newly opening flowers is
probably a characteristic of certain species that have evolved where
the mechanism of pollination is available over a long period but not
reliable in all years. Annuals grown in gardens have been selected
for this characteristic. It is also well known that sterile
selections have longer-lived flowers, whether the sterility results
from hybridization or from the absence of reproductive structures as
in some double-flowered plants. You can see this especially in
Paeonia, where the single-flowered true species have short-lived
flowers. (Mine are all available to pollinators, so I don't know if
non-fertilization would induce the flowers to "last" longer.)

One way to get a longer season of bloom is to grow plants from
different populations of a species. It is curious to see how
seedlings from one place may flower several weeks before those from
another. It is also annoying if you have only one clone from one of
the populations and would like to get seed from it.

Jane McGary
Portland, Oregon, USA