Hedychiums was Re: Leaf-Cutter Bees...Cumbrian Gardeners

Tim,

In many cases, the average ambient temperature governs the germination
of pollen when it is deposited on the stigmatic surface.  In
sub-tropicals this can be as low as 10C or as high as 25C depending
upon the type of plant.  

The floral structure of Hedychium is initially somewhat confusing with
pollen bearing masses carried in a single anther which appears to be
partly fused to the stigma thus forming a 'column' (gynostemium).  In
reality, the style of the stigma passes through the anther lobes and
what looks to be a single, complicated structure, is actually two
floral parts, one encasing the other.  In a true column as exhibited
by members of the Orchidaceae, the style of the stigma and filaments
of the anthers are completely fused to form a single structure with
the pollinia separated from the stigma by a rostellum - a modified,
sterile third anther which serves to prevent self-pollination.

If you look carefully at Hedychium gardnerianum for instance, the
pollinia are clearly visible just below the stigma.  As the flowers
age, the filament lengthens and the pollinia hang free.  It is at this
stage that the stigmatic surface is glistening and 'ripe' enough to
accept pollen.  You can manually transfer it and providing
temperatures remain high enough for several hours, fertilisation
should take place.  

Through most of their range (South East Asia including Japan),
Hedychiums are naturally pollinated by moths, small butterflies and
various other nectar feeding insects.  Certain other members of the
ginger family are occasionally pollinated by birds as well, but nectar
feeding birds are not generally the major pollinating factor
throughout much of the Zinziberaceae. 

In the small, densely flowered species such as H. densiflorum, once
the pollinia are hanging free, pollen can easily fall onto the stigma
of adjacent flowers.  This often happens in windy weather and even a
beetle 'bumbling' its way amongst the flowers will prove an effective
pollinator.  I suspect the comparatively high levels of 'in breeding'
amongst the small flowered species are the reasons for the large
numbers of variants known within H. densiflorum and to a lesser
extent, H. coccineum.  

In the UK there are at least 5 clones of H densiflorum in cultivation:
(Wallich 6552.,  KW 13875 - named and awarded at the RHS in 1974 as
'Assam Orange',  L.S & H 17393., Schilling 870 - named and awarded in
1982 as 'Stephen') although 'Assam Orange' is possible the most widely
grown.  Mine (allegedly the fifth clone) is a very good form, proving
to be rather hardy and with better, slightly larger flowers than
'Assam Orange' , but with a shorter, more densely compacted raceme.  I
cannot verify its source since it does not appear to agree with any of
the current, identifiable collections of this species.  It was thought
to originate from the Royal botanic Garden, Edinburgh via Cotehele and
in theory should be fma. Wallich 6552, but in reality it is not.  As a
young potted plant it survived having its roots frozen solid on
several occasions in the winter of 1994-5.

I hope to have it identified later next year, but if it does prove to
be a fifth and as yet unidentified clone, it will be named and
exhibited for an award at the RHS in late summer 2000.  Several
'Hedychium aficionados' who have already seen it, agree that it is
superior to 'Assam Orange' .  Seeds of this clone were sent to Sean
O'Hara, but I suspect they might not have germinated since they've
proven rather unreliable unless very fresh.  Plants raised from my own
seed collected in 1997 are very uniform in growth although the telling
factor will be when they flower - hopefully by 2000/2001.

Dave Poole
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