Editing Cycas bougainvilleana

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Michael Ferrero has invited me to contribute an informal
series of articles on my trip to PNG in July and August 1996.
During six weeks at Port Moresby and in Madang, Oro and Milne
Bay Provinces I was told about or saw nine types of cycads.
These might be different species (I saw
''[[Cycas campestris]]'', ''[[Cycas  rumphii]]'' and
''[[Cycas  schumanniana]])'' or intergrades. An intergrade is a
plant showing features of two species despite the fact that
one of the species does not occur in the area.

Let me backtrack. After my return, I attended a meeting of
PACSOA where Ken Hill of Sydney Botanic Gardens gave an
excellent illustrated lecture on the genus ''Cycas'' in
Asia. He later sent me a copy of his fascinating article on
the ''[[Cycas rumphii]]'' complex in PNG. Hill erected a new
division of the genus ''Cycas'' for ''C. rumphii'' and
related species
(''apoa, bougainvilleana, micronesica, schuman-niana'' and
''seemannii'') and published the type
descriptons of ''apoa, bougainvilleana'' and ''micronesica''.

A shared feature of the ''C. rumphii'' group is a spongy
flotation layer in the seed which facilitates an aquatic
dispersal mechanism. The seeds float! This layer is also
found in ''[[Cycas circinalis]]'' and ''[[Cycas thouarsii]]''.
The presence of the layer in all eight species could have
been caused by their descent from a common progenitor or
convergent evolution (independent development of the same
feature in unrelated populations). Natural forces can scatter
floating seeds widely. The colonists' flowering produces a
population of variable hybrids. There will be no sign of the
source of the hybridism when the colonists die. Later storms
can cause further injections of foreign genetic material. A
distribution map in Ken Hill's article shows that
interspecific intergrades occur through a wide area of
Melanesia.

I spoke to Roy Osborne at the March PACSOA SQG meeting. His
opinion is that the intergrades are possibly the product of
prehistoric distribution ranges of species being larger than
they are now. A new assay technique will allow the parentage
of intergrades to be definitively determined. Given that some
cycad seeds are used as food in PNG and that long distance
canoe routes existed in prehistory, some seeds may have been
transported by human agency.
How does this relate to my trip? I spent 11 days at Tuff in
Oro Province with the nice people who run the Konambu
Guesthouse.

In the village was a cycad around 750 mm in height. Its
leaflets were recurved. As they grew out from the rhachis,
they reached a certain point and curved towards the trunk. I
never saw the mature plants on the mountain. It was just too
far. I walked up there twice and saw many birds, including
hornbills, but the only cycads were seedlings. An immature
plant beside the track caught my attention because its leaves
were undulate like ''[[Cycas apoa]]''! The larger plant at
Konambu village did not have undulate leaves. The range of
''C. apoa'' extends from the Huon Peninsula in Morobe
Province to points west in Indonesia. Tuff is a long way east
of the Huon Peninsula. Tufi's mostly rocky coastline seemed
inhospitable to floating cycad seeds and I thought the Tuff
cycad was a new species. I now believe it is an intergrade
between ''C. scratchleyana'' and ''C. bougainvilleana''
with maybe a gene of ''C. apoa'' included.
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===Contributed by: ===
Tony Huntington from '''Palms & Cycads''' No. 58, Jan-Mar 1998


===External Links:===
[https://www.cycadlist.org/taxon.php?Taxon_ID=70 World List], 
[https://www.iucnredlist.org/details/full/42070/0 IUCN],
[https://www.jstor.org/action/doBasicSearch?Query=Cycas+bougainvilleana JSTOR],
[https://www.trebrown.com/plant_info.php?species=Cycas+bougainvilleana Trebrown]
</p>
[https://www.google.com/search?q=%22Cycas+bougainvilleana%22&amp;num=10&amp;sa=Google+Search Google],
[https://images.google.com/images?q=%22Cycas+bougainvilleana%22&amp;hl=en&amp;btnG=Google+Search GoogleImages],
[https://www.flickr.com/search/?q=Cycas+bougainvilleana Flickr],
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[[Category:Cycas|bougainvilleana]]
[[Category:Cycad|Cycas_bougainvilleana]]