Dale Borders, so far and by far
our biggest contributor of seed, wrote this piece when
I asked him if he'd like to share some thoughts about
pollination. Last time I checked, he'd attempted
pollination on at least 460 different plants in over
130 genera. -Troy
Thoughts On
Pollination
by Dale Borders
Contents:
Pollinating Your
Flowers
Reasons For Capsule Failure
Difficult Genera
Easy Genera
Multiple Cultivars
What's In The Capsule?
Cross-contamination Of
Seed
Record Keeping
What To Expect From Your Flasking
Service
Pollinating Flowers Of Failing Or
Moribund Plants
Enjoying Your Flowers
POLLINATING YOUR FLOWERS
Pollinating your orchid flowers can be a rewarding and
delightful experience sometimes muted by a variety of
surmountable obstacles. If a flower is expendable remove one
and dissect it to learn where all the parts are, how they
respond when manipulated, and what they feel like with a
toothpick. One of the biggest problems is manipulation of
the pollinia; certainly a tooth pick isn't the pollination
mechanism to which orchids have evolved. Insert a toothpick
into the corolla, and using a slight upward pressure against
the column, slowly withdraw it. Keep in mind that a
'natural' pollination of an orchid flower isn't usually a
'same flower' pollination; usually, the pollinating agent
sticks it's head, beak or body into the flower, gets some
stigmatic fluid on the head, beak or body, backs out of the
flower, picks up the pollinia (the anther cap is suitably
hinged to only open on egress of the pollinating agent), and
goes to the next flower. The 'next' flower is where the
pollen is deposited. If you try to remember the sequence of
events for a 'natural' cross-pollination your movements
should be appropriate. On ripe flowers (when gently removing
the toothpick), you can often feel the increased resistance
when the toothpick encounters the stigmatic cavity and the
viscous fluid contained therein.
REASONS FOR CAPSULE
FAILURE
There are many reasons for a pollinated flower failing to
produce a seed capsule. Quite possibly, the most common
reason for failure is self sterility; some flowers just
won't accept their own pollen. Flower age is another reason
for failure. Many flowers may live longer than their pollen;
perhaps the stigmatic fluid is lost or diluted from
watering. It's possible that time of day is a significant
factor in a successful pollination; certainly the time of
strongest fragrance could herald receptiveness. Many flowers
are just 'tricky'. Most members of the Gongorinae (Gongora,
Stanhopea, Sievekingia, etc.) have a slitted aperture to the
stigma that often only becomes apparent after the pollinia
are removed. Small flowers are inherently difficult to
pollinate because of their size and quite often the column
(conduit to the ovary) may be broken in an effort to control
the flower, the stigma may be damaged, or the anther cap may
be confused for the pollinia. In many attempts a jeweler's
head magnifier is a necessity. Poor cultural conditions may
disfavor conditions for capsule maturation as well. Many
plants have been treated with colchicine to induce
polyploidy and concomitant vigor and size; often
'colchicined' plants are sterile.
DIFFICULT GENERA
Some genera are difficult to pollinate successfully. Members
of the Oncidiinae and the genus Coelogyne seem to be
especially reluctant to self pollinate. Although the
previously mentioned orchids are difficult to self, there is
still good reason to make attempts at selfing as capsules
are occasionally produced. It's certainly possible that many
ARE self-fertile, but hand pollination doesn't satisfy
receptiveness criteria.
EASY GENERA
Some genera are easy to pollinate successfully. Most members
of the Laeliinae (Laelia, Cattleya, Epidendrum, etc.)
produce capsules freely.
MULTIPLE CULTIVARS
Certainly, multiple cultivars (different clones) of
self-sterile plants are desirable if your cultivar is self
sterile. If space in your growing area is limited, exchange
of pollen with the owner of a different cultivar is a good
option. Cared for properly, pollen is often viable for weeks
to months.
WHAT'S IN THE CAPSULE?
Harvesting a seed capsule is an exciting and fun culmination
of your effort and time. So what's really in the capsule?
Most often you'll see free-flowing seed and send it to the
flasking service with justified great hopes. Occasionally,
you'll find nothing inside the capsule. Even if you see what
looks like seed, it may contain no embryos. If there is
seed, it may be infused with the mycelia of fungus. You may
want to ask your flasking service to provide you with a
viability report upon receipt of the seed. If you're
rebuffed in your request and you don't want to risk paying
for flasking seed that can't grow, find another flasking
service; you'll be charged for sowing whether the seed is
viable or not.
CROSS-CONTAMINATION OF
SEED
If you find that you must prepare and dry two or more
capsules at one time, it's imperative that seed from one
capsule not be allowed to contaminate the seed packet of the
other capsule(s). After handling a capsule it's crucially
important to wash your hands, any tools used in the
preparation of the capsule, and any vessels previously used
for seed drying with soap and water. Use a paper towel or a
fresh hand towel for drying. Seed of many genera (Calanthe
especially) is extremely light and easily becomes airborne
with the slightest breeze. If just a few seed germinate in a
flask, the possibility exists that the flasked seed is
actually sterile and contamination occurred from seed being
dried nearby. Certainly the commercial value, and to a
lesser extent the hobbyist value, of such flasks would be
greatly reduced.
RECORD KEEPING
It's an onerous task and easily deferred, but record keeping
is important. If a pollination attempt fails you may want to
recall flower age, number of flowers pollinated, and date of
the previous attempt. If your pollination attempt is
successful, age to maturity, quantity of seed, and quality
of seed could be recorded entries. If you attempt another
capsule, maturation time of the first capsule is of
importance. Brightly colored stringed baggage tags loosely
attached to the pollinated flowers with the date of
pollination, number of flowers pollinated, and parents, make
your inspection rounds quicker, easier, and more complete if
you have several capsules maturing.
WHAT TO EXPECT FROM YOUR FLASKING
SERVICE
This varies a lot, but possibly you'll want to get viability
checking when they receive the seed, either by microscopic
examination for embryos (quick) or by tetrazolium staining
(takes days), and certainly get periodic reports about
germination and growth. Normally you will pay to have the
seed sown, then later pay a deposit for making
reflasks/replates, though there are exceptions, such as with
Meyers'
programs.
POLLINATING FLOWERS OF FAILING OR
MORIBUND PLANTS
Quite often orchids initiate an inflorescence as a response
to severe stress prior to death. A quandary then arises:
should you attempt to set a seed capsule? will the plant be
able to support a capsule? will the effort necessary to
support a capsule kill the plant? HELP!!!!! Certainly, the
value and replaceability of the plant should be considered
first. If the plant is valuable (for whatever reason) assess
the vigor of the plant as best you can and proceed on your
best hunch. Things to consider are root health, past
performance and vigor of the plant, and proximity of the
next growth cycle. If pests have caused the decline of your
plant, remain vigilant to ensure that re-infestation doesn't
occur; weakened plants are disease prone. If you decide to
pollinate, remove all flowers except the flower(s)
pollinated. Another option is to contact a tissue culture
lab for possible propagation.
ENJOYING YOUR FLOWERS
When we pollinate a flower it usually wilts in a few
hours to a few days as a response. Your pollination attempt
then is an ideal time to dissect your flower (leaving
reproductive elements undamaged and intact) and truly enjoy
a smaller but equally enjoyable aspect of your flower.
Normally we only see the outer aspect of our flowers but
sometimes the truly remarkable views are within. A whole new
range of hairs, calluses, colors, fringes, spots, dots and
stripes await us if we sacrifice a flower to curiosity and a
hand lens. Even if we don't pollinate a flower, removing one
to dissect simply to get the same view a pollinator gets is
worth more than the flower. And it'll still bloom again the
next season.
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