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Please click on a letter to list all weeds in archive beginning
with that letter.
Dietes grandiflor
Drymaria cordata
Dyschoristie depressa
Dietes grandiflora
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Date: Mon, 21 Jul 2003
From: Sally Vidler <sally.vidler adelaide.edu.au>
I've had an enquiry from the SA Transport
Authority who have been using Dietes grandiflora is some of their
urban roadside corridor plantings. Rod Randall sites it as an addition
to the Garden Thugs list, but I've no references as to where it
has gone weedy, or what level of threat it poses.
Has anyone come across it?
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Date: Tue, 22 Jul 2003
From: Wendy <woobindapipeline.com.au>
I don't know D grandiflora, I only know D. iridioides and D. bicolor.
Both of these are used very widely in urban street etc plantings
round here (northern Melbourne suburbs). It is nice, and a relief,
to see local Dianella sp etc being used more and more now.
2 comments I would make.
A number of years ago I grew some D. iridioides from a friend's
garden to plant in my nature strip which I have planted up with
natives, in particular indig. stuff. At the time I was eroneously
told it was a native. In this setting, with a thick wood mulch and
little supplememntary water through our severe ongoing drought,
beneath a LARGE 'Brush Box ' street tree they are readily self seeding,
as well as the clumps constantly enlarging. They clumps don't seem
to strangle themselves to death like some of the natives can if
not burnt or grazed. (One of the originals has been halved in size
over the past 6 months or so because it is beside the footpath and
EVERY passing dog - MANY are walked on my street -pisses, some defacate,
on it. With no rain to wash it away this became too much for the
plant! ) ALSO
A year or two back a S African lady? (I think) weedo visited friends
in oz and toured about. I recall she wrote a piece to enviro weeds
commenting on her observations. I'm certain she commented in this
about the widespread plantings of Dietes species she had noted and
she warned that these had the potential to become a serious future
weed problem. On thing they do she noted (and this occurs in my
naturestrip) is continue to flower out along the same flowering
stalk repeatedly in the one season, and then in subsequent years.
With time the weight of seed pods causes this to droop to, and lie
along the ground where it can continue to produce flowers and seed
pods - a very safe and effective way to spread the seeds ( sort
of like - but not - stolons).
I have tried a couple of times to find this item in my old enviroweeds
items but have not been able to. If anyone can send me a copy I
would appreciate it, or tell me the authors name as I could probably
find it with my own search.
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Date: Tue, 22 Jul 2003
From: Tony Rodd <tonyroddisp.net.au>
There has been much confusion about the names Dietes grandiflora
and D. iridioides, but it was sorted out in a 1981 revision of the
genus by Peter Goldblatt, who is the ultimate expert on African
Iridaceae. I don't have the revision handy, but I do have the new
Color Encyclopedia of Cape Bulbs (Manning, Goldblatt & Snijman
2002) which has a good commentary on them, and I quote the whole
of the relevant paragraph.: The flowers of Dietes are pollinated
mainly by bees. In most species they are short-lived and last less
than a day, but they last 3 days in D. grandiflora N.E. Brown from
the Eastern Cape. Dietes iridioides, the only species to enter into
the Cape Floral Region, has the widest range of any in the genus,
extending from near the town of Villiersdorp, near Cape Town, to
the evergreen forests of East Africa and Ethiopia. Only plants from
the Cape flower in late spring and early summer, but there is otherwise
little difference in populations from the different ends of the
range. Unlike its more glamorous relative, D. grandiflora, which
has large, long-lasting flowers with brown markings on the tepals
and violet style style arms, D. iridioides is very plain with small,
off-white flowers with pale violet style arms that last only a day.
The two species are often confused in the literature, and the name
D. vegeta has been misapplied to both in the past. Dietes iridioides
is best treated as a plant for shady sites and does best when watered
both summer and winter. Dietes grandiflora is a favorite street
street planting for it tolerates only occasional watering and persists
even when treated poorly. Plantings of that species make a fine
display for 3-5 years, after which they become overcrowded and moribund.
All species of Dietes can be grown from rhizomes. Seeds are often
slow to germinate and may not reach flowering size for 3 years.
D. bicolor of course is not easily confused with the above species,
having lemon-yellow flowers with a chocolate blotch.
Both D. grandiflora and D. iridioides have been grown in NSW for
a very long time. When I worked at the Botanic Gardens I sorted
out the plants there using Goldblatt's 1981 revision. D. iridioides
was lower and more sprawling and its inflorescence lasted several
years, almost touching the ground if seed pods accumulated. D. grandiflora
was the one always selected for mass displays, even though the gardeners
had no idea that there were 2 different species.
I do a lot of bushland survey work and have only ever found Dietes
naturalised to a minor extent, and my impression is that it was
generally D. iridioides. Of course the situation could well be different
in other parts of Australia where climate and soils are different.
And I don't discount the possibility of it being a 'sleeper' weed.
I have never seen D. bicolor naturalised.
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Date: Fri, 25 Jul 2003
From: Rod Randall <RPRandallagric.wa.gov.au>
See below an extract from the most recent EWAN infonotes on Dietes
in cultivation in Australia.
Moraea there and Everywhere
Dr Roger Spencer. See the full article in Australian Horticulture,
April 2003.
An number of EWAN members have been concerned about Dietes in public
and private plantings over the last few years. remember Joanna Seabrook
making disparaging comments about massive roadside plantings back
in the late 1990's. Dr. Roger Spencer is an expert in horticultural
flora in Australia and in a recent Australian Horticulture article
had some interesting comments about Dietes and Moraea species. Here
are his comments on identification and nomenclature issues from
this article.
-------------------------
- Dietes bicolor - butterfly iris - has leaves with prominent
midribs and yellow flowers with dark brown nectar guides.
- Dietes iridioides - African iris - is a compact plant,
with leaves to about 0.5 metres long without a prominent midrib,
and white flowers 3.5 to five centimetres wide with pure white inner
petals.
- Dietes grandiflora is generally more robust than D. iridioides
and has leaves 0.75 to one metre long, also with inconspicuous midribs.
The white flowers are six to eight centimetres wide, with the inner
petals having brown marks.
Contrary to general (and published) opinion, this appears to be
the more commonly cultivated of the white flowered species. It is
the white flowered plants that have caused the identification difficulties,
although the characters described above are distinctive. Part of
the problem may be due to the occurrence of hybrids.
The most important nomenclatural point is that Dietes vegeta is
the name generally used in horticulture for plants that are, according
to the literature, really D. iridioides.
However, it seems that some plants in Australia referred to as
D. iridioides are, in fact, D. grandiflora. Moreover, on the nomenclatural
front, we can easily start going around in circles.
There is, a genus closely related to Dietes called Moraea, and
within that genus there is a Moraea vegeta (a name easily confused
with Dietes vegeta). In some references the name Moraea iridioides
is used for the current Dietes iridioides, as is the name Iris moraeoides.
The message is that if you come across these plants, make sure you
have checked the differences between Dietes iridioides and D. grandiflora,
and note that the name Dietes vegeta is a misleading horticultural
invention.
Drymaria cordata - Tropical chickweed
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Date: Tue, 10 Dec 2002
From: Ross Macleay<lizardlandbigpond.com>
Tropical chickweed, Drymaria cordata
subsp. diandra is listed in Flora of NSW as a native species.
I dont remember seeing it until the 1990s, and it appears to be
gradually moving south. It has become increasingly common on the
NSW north coast in moist forests and is a common plant encountered
by gardeners, restorers of rainforest and riverside vegetatation.
It likes sunny cultivated well watered soil.
Opinions differ about its status and its
effects. Some bush regenerators cant stand it. Personally, I am
not greatly troubled by it - except for one thing. Is it actually
native? I keep getting conflicting advice. I would like to think
it was. There would be less work to do. And whatever the answer,
it would remove a bit of ambiguity from some of the restoration
work that I and others do.
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Date: Tue, 10 Dec 2002
From: Rod Randall <RPRandallagric.wa.gov.au>
Drymaria cordata (L.) Willd. ex J.A. Schultes ssp. diandra
(Blume) J. Duke basionym: Drymaria diandra Bl. is considered
a native of northern America. I have no other records that suggest
otherwise.
Drymaria cordata (L.) Willd. ex Schult. is a cosmopolitan
tropical/subtropical species and ,along with Drymaria cordata
ssp. cordata (L.) Willd. Ex Schult., is listed as present in Queensland
from Cape York region to the NSW border and probably well below
by now...
Drymaria cordata certainly has a well established weed pedigree
around the world in South, Central and North America, Asia and Australia.
Wherever its ID and/or origin, native or not you can choose not
to use it.
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Date: Tue, 10 Dec 2002
From: Lauren Appleby <laurenprsc.qld.gov.au>
Tropical Chickweed is considered native to SEQ where it fulfills
a role as a coloniser, utilising disturbed or open sites. Check
with your State Herbarium, to see if its native to your area and
if it is celebrate the cover it provides for regenerating seedlings
and its role as a green groundcover, otherwise... control may be
necessary
back to top
Dyschoristie depressa
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Date: Wed, 18 Jan 2006
From: Scott Edwards <Scott.Edwards@nrm.qld.gov.au>
I have had a request for help with any
information on Dyschoristie depressa (Acanthaceae). There are
a number of infestaions in and around Brisbane, and not much is
known about this plant. It is the same family as Hygrophila and
appears to have a very similar growth habit.
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Date: Wed, 18 Jan 2006
From: Rod Randall <RPRandall@agric.wa.gov.au>
Google searches are worthwhile.
For instance I searched for "Dyschoriste depressa"
and found a wonderful document by a Beth Houghton called
Camphor laurel and Dyschoriste depressa By Beth Houghton
Its an agriculture assignment so Beth is obviously a student
but its a pretty decent summary of the problems they are having
with these two weeds and it contains some useful control and management
advice on both species. You can download Beth's assignment here.
http://www.kedronbrook.org.au/__data/page/12816/Beths_Agriculture_Assignment
.pdf?MySourceSession=df4b101a4e7e6a7b2e3fcc41f02f1a2a
Another source of data I found was a pdf poster by Kylie Withers,
a catchment coordinator from the Kedron Brook Catchment
http://www.kedronbrook.org.au/news,_views_&_events/?f=24888
You can obtain the large version of her poster from news@kedronbrook.org.au
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Date: Wed, 18 Jan 2006
From: Scott Edwards <Scott.Edwards@nrm.qld.gov.au>
Thanks Rod
I had found both these documents. The Pine Rivers Catchment,
adjacent Kedron Brook Catchment is where the request for info
has come from so they are looking for all the help they can get!
As Dyschoriste depressa is in the same family as Hygrophila, I
made some suggestions that it may be susceptible to heat, salt,
dodder and competition from native vegetation, but I am not certain!
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Date: Wed, 18 Jan 2006
From: Tim Odgers <pinerivers@bigpond.com>
I was the originator of the original query through Scott.
Yes both documents are excellent and have served us well; we
are currently working with Pine Council to trial chemical treatments
and develop a further information brochure.
I guess when the key information on a relatively new and potentially
very severe weed can only be sourced from high school students
and community groups that it is relatively unstudied - great to
see the community leading the way! However, this scares me as
it appears to be a potentially very nasty weed and that the horse
has just about bolted and with mowers spreading it around there's
a real chance of cross catchment spread into the Pine Catchments
which I'd hate to see... "a stich in time"
Dyschoristie depressa is a very vigorous plant that handles a
very wide range of environments (from growing (in prostrate form)in
hot dry mown lawn to rampant in a heavily shaded waterway), loves
disturbance, seeds and germinates extremely well as spreading
vegetatively (by mowers) too, and I would love to know more about
the seed longevity, chemical treatments trailed, containment strategies
etc.
They love it in Africa for fodder and stream stabilisation
I'd love to hear from anyone who knows if it grows elsewhere
in Australia or knows of further information on it.
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Date: Fri, 20 Jan 2006
From: Dorean Hull <Dorean.Hull@brisbane.qld.gov.au>
Further to the information you've already been given. Brisbane
City Council has initiated an eradication program for Dyschoriste
depressa (Dd). This comprises:
Declaration of Dd under Council's Natural Assets Local Law 2003;
Preparation of a poster/alert for the community (by Kylie Withers);
Treatment trials (you can contact me for the results of those);
Inclusion of vehicle hygene requirements in our mowing contacts;
Monitoring of compliance by our contractor coordinators;
Survey and mapping of all known and potential locations, including
private land (though Sheldon, has sent me more since);
Total $45,000 this FY and guaranteed funding for at least two
more years under the Wipe Out Weeds program.
The money will be spent on around 6 sites this fy. Because it's
a new weed it's hard for us to know how many treatment rounds
will be required in some sites before it can go on routine monthly
inspections and spot spraying.
Sites were prioritised in the following order:
Infestation in or near waterways (most difficult to treat, but
highest potential impact/risk);
Infestations in the upper reaches of a catchment (top down approach);
Small infestations that will be easy and cheap to treat (early
detection and eradication principle).
I'm keeping a record of this entire process for future reference.
A sample is being taken and sent to the Queensland Herbarium at
each location found to ensure a record of it's spread in the area
is in place.
I totally agree regarding the need to act early and apply the
precautionary principle when in doubt. This species was spotted
three years ago by a local TAFE College teacher when there were
only two plants on the side of the waterway. Within a year, they'd
covered the entire bed and banks of that section of creek.
Fortunately, Pine Rivers Shire Council's Craig Welden acted quickly
when I contacted him about the infestations found on PRSC land.
Tim, I will send you through a full list of all the people you
should coordinate your efforts with.
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