Editing Hydriastele costata

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[[File:Hydriastele_costata.jpg|frame|Figure 1. ''H. costata'' in habitat, Morobe, PNG.]]
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''Hydriastele costata'' (Beccari) is the only
species of the genus to occur naturally in Australia, where
it is confined to the extreme north of Cape York Peninsula.
The genus has nine species (1) and the present species is not
endemic in Queensland but has a wide distribution in New
Guinea and the nearby Aru Islands and Bismark Archipelago.
In Queensland ''H. costata'' occurs in a few sites on
the extreme north of Cape York Peninsula, in the township of
Bamaga and through the "Four Mile Scrub" along the road to
Somerset, along several streams draining into Newcastle Bay
just south of Somerset and sporadically in various other
sites in that region. Further south along the east coast of
the Peninsula there are several populations around Iron Range
in the Lockhart River region.
 
Around Bamaga the palm attains its best form, it is a
tall and very handsome single trunked tree reaching to 30m
or more. It favours moist places on seasonally flooded flats
or on steep slopes in volcanic soils, often forming groves
which are conspicuous from the air due to the great height of
the trees and their emergent nature. In the town of Bamaga
some very fine specimens can be seen from the garage and
workshop on the airstrip road, in a swampforest on the other
side of the road. Along the road to Somerset there are
several very fine stands, visible from the road in the "Four
Mile Scrub" along a low swampy depression.

Near Iron Range airstrip one can see several lines of
this palm (running down Lammond Hill) from the regular
passenger plane. Further groves occur near the Lockhart River
village along Quintel Creek on Line Hill and behind the
community farm. There are several other occurances there but
these are most easily located. In the Iron Range area the
palm grows almost exclusively around springs and along
permanent streams in rainforests and is quite abundant.
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''H. costata'' is characterised by its height,
relatively straight and upright trunk and by its crown of 14
- 18 long, straight leaves with pendulous leaflets. The crown
itself is as large as a healthy adult coconut tree and looks
similar from the air except that it grows in rainforest and
the drooping leaflets are somewhat conspicuous.
Throughout its range in north Queensland this species
shares its habitat with ''Pandanus lauterbachii'', a
semiaquatic pandan which is remarkable for the length the
juvenile plants leaves can attain in shady sites (10 m. or
so). The association is so reliable that I use
''H. costata'' as a sign of the presence of
''P. lauterbachii'' during study trips.
This association is no mere coincidence, both species
are New Guinean in origin and both have arrived in Queensland
recently (geologically speaking) from there, probably by way
of the same dispersal agent - birds. Both species have small
seeds produced in abundance and both occur together in New
Guinea, having the same set of environmental requirements.
However, both species have a degree of environmental
amplitude which allows them to exploit slightly different
sites under favourable conditions.

''H. costata'' groves could well be called Monocot
Swamp forests because of the rather extraordinary richness of
monocots which live there. The ''H. costata'' forms a fairly
even but light canopy at about 25 m. with a subcanopy of
''Pandanus zea'' at 12 m. and a dense undergrowth of
''P. lauterbachii'' at 10 m. Below this is a scattering of
pandan-like sedges - ''Mapania macrocephala'' to 3m.,
gingers to 4 m. and climbers of ''[[Calamus aruensis]]''
(around Bamaga only), ''C. warburgii'' and the solitary
rattan ''C. hollrungii'', the climbing pandans
''Freycinetia marginata'' and ''F. percostata'' and
various aroids. Occasional ferns and dicot trees are usually
present but not abundant and epiphytes are common.
Because of the humid and hot conditions the vegetation
is rather dense around such forests but inside movement is
not particularly difficult due to the supressing effect on
ground herbage of the large leaves and coarse litter from
above. Access is easy via the streams which drain such
forests and the cool running water is usually potable.

''H. costata'' is easy to cultivate in the tropical
lowlands north from about Townsville but requires a sheltered
site when young. The plants are not tolerant of long cold
periods, dislike dryness and are ruined by high winds. A
friend has some in his garden in Atherton, the cold winters
are too severe for the plants and although they do not die
the growth is extremely slow and the future seems not to be
good for them. However in Cairns the plants should thrive
with little trouble where they would make dramatic landscape
features. The seedlings resemble those of ''Areca'' and
''Pinanga'' to some degree, indeed these genera are
related, but closer affinities are with ''Hydriastele''
and ''Nengella''.

===References: ===
(1) Essig, Frederik B., A Synopsis of the
Genus Gulubia. Principes, 26(4), 1982, pp. 159-173

(2) Bailey, Frederick Manson, Queensland Agricultural
Journal II (129)

===Contributed by: ===
Robert Tucker (Text - from ''Palms&Cycads'' No. 13, Oct-Dec 1986)<br/>
Rolf Kyburz, (Figure 1)


===External Links:===
[https://powo.science.kew.org/results?q=Hydriastele%20costata Kew], 
[https://www.palmweb.org//?q=cdm_dataportal/taxon/354077a0-bce3-4901-9f11-46c72065cb9d PalmWeb],
[https://www.jstor.org/action/doBasicSearch?Query=Hydriastele+costata JSTOR],
[https://www.trebrown.com/plant_info.php?species=Hydriastele+costata Trebrown],
[https://keys.trin.org.au/key-server/data/0e0f0504-0103-430d-8004-060d07080d04/media/Html/taxon/Hydriastele_costata.htm ATRP]
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[https://www.google.com/search?q=%22Hydriastele+costata%22&amp;num=10&amp;sa=Google+Search Google],
[https://images.google.com/images?q=%22Hydriastele+costata%22&amp;hl=en&amp;btnG=Google+Search GoogleImages],
[https://www.flickr.com/search/?q=Hydriastele+costata Flickr],
[https://www.google.com/search?q=%22Hydriastele+costata%22%20site:https://www.palmtalk.org/&amp;sa=Google+Search PalmTalk]
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[[Category:Hydriastele|costata]]
[[Category:Palm|Hydriastele_costata]]