Leo wrote:
I know the advice to cut off spent spikes to 'conserve the strength' of
a plant represents the wisdom of generations, but it doesn't correspond
very well to my recent experience with phals or to my own humble opinion
of biology.
A previous poster urged us to think of what happens in nature but my
conclusions are somewhat different: the flowers are long lived and
wilt as soon as pollinated so the strategy must be to persist until
a (possibly infrequent) pollination event occurs. If weather, passing
wildlife or other hazards of life in the wild damage the flowers, it
may make sense for the plant to sprout another branch off what's
left of the spike. Presumably there's some regulatory mechanism
that only allows this if the plant can afford it (admittedly this
may be partly bred out in domesticated varieties).
What is the metabolic cost of a flower spike? Well obviously it is a
bunch of growth that doesn't photosynthesise much, but it doesn't
weigh more than a big bunch of aerial roots such as phals often have
and no one worries about those sapping the life of the plant.
Leo,
As a biologist, I would have to agree with the sentiment of your
post, but I think you underestimate domestication. Yes, there is (has
to be) some regulatory mechanism that has evolved to limit the blooming
capacity of the phalaenopsis. It does make logical sense, assuming that
these plants are perennial and have evolved to bloom over many years,
although a single sucessful pollination event and seed distribution
would ensure evolutionary 'success' in the strictest sense. An
inflorescence is a substantial metabolic cost to produce, and perhaps
less to maintain, but reblooming a spike invokes the 'production cost'
more frequently. Seed production is expensive, very expensive, if we
let it get that far. Also, it may look like the mature flowers are not
doing anything, but they are respiring (consuming sugars that the green
parts must make) and transpiring (releasing water that the roots must
uptake). If they aren't doing those two things they are dead, and none
of us want that. They aren't contributing much, and they are costing at
least a little. Presumably, based on collective experience, a healthy
happy plant has little trouble paying the bills.
However, we aren't growing these plants in their native
environment. Environmental stimuli which might serve to limit blooming
may not exist in the typical windowsill. More importantly, we have
spent a hundred years breeding the limiting capacity out of the genus.
Generations of orchid breeders have selected for free blooming, long
blooming, and large (more 'metabolically expensive') flowers. Ease of
bloom is probably one of the most important characteristics, and if
breeders have done their job the plants should be too genetically stupid
(to coin a phrase that needs coining) to know when to stop blooming.
This is a good thing for orchid growers (sellers, anyway). If we were
growing species orchids on trees in SE Asia, then there wouldn't really
be an issue.
Interesting thoughts though. I'd never really considered it
before. And I may have falsely considered it just now...
Rob
--
Rob's Rules:
http://www.msu.edu/~halgren
1) There is always room for one more orchid
2) There is always room for two more orchids
2a. See rule 1
3) When one has insufficient credit to purchase
more orchids, obtain more credit
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