Visit to the Aquatic Candy Store for
Acorus - Sweet Flag
by Dave Brigante, Oregon USA
Click images to enlarge
This unique family of marginal aquatic plants allows for many
different fundamental uses while also lending itself to being
versatile enough that creativity in design comes easily. The
Acorus range in color can put it into a small pond
as unifier or can bring out a backdrop in a large pond setting
through its bright variegation. That being said one of its best
uses is in a water bowl, as a focal point or ringing an edge
of a miniature fairy pond. This family, often taken for granted
in the aquatic plant kingdom, eventually finds its way into most
well balanced pond designs due to its unrelenting availability,
reliability and wide range of assorted sizes and colors.
Most growers of Acorus generally think of the genus as
having only two species. The first, Acorus calamus, from
temperate and tropical Asia, may have become somewhat naturalized
here in the US, but it is actually our own native sweet flag
Acorus americanus that we see most frequently in the wild.
In the trade, these are sometimes interchangeable and rarely
sorted out, leading to nomenclature difficulties.
Neither of these species is promoted nearly as much as Acorus
calamus Variegatus, variegated sweet flag. The
other main species in the genus is Acorus gramineus, also
known as Japanese sweet flag, native to temperate and tropical
Asia. For convenience I will only refer to the two better known
species (calamus and gramineus) to reduce confusion.
< A. gramineus
There are some marked differences between the two species.
The A. calamus group loses its leaves each winter while
A. gramineus does not. The A. calamus growth
habit is more of a runner and the A. gramineus stays in
a clump. A. calamus is limited to being either green or
variegated, and A. gramineus has shades of yellow, white
and green with some variegated varieties as well. Last, A.
calamus grows to a height of 2.5'-3' (.8-1 m), much taller
than A. gramineus that tops out at 12" (.3 m) and
shrinks down to just 2-3" (5-8 cm) in its shortest form.
Both are stunning in their own right.
Above right - A. calamus
'Variegatus' in winter^>
Right - A. gramineus 'Odon' in winter >
All are called sweet flags for two reasons. A. calamus
often looks just like blue flag iris when not in bloom and has
been mistaken for iris in the wild. That is until the leaves
are crushed or some of the smaller varieties get walked on and
the sweet flag fragrance is released into the air. This sweetness
of the roots and leaves was reportedly used to make candies,
potpourri, natural insecticides, beer, and had many medicinal
uses, too numerous for listing. Its availability in the wild
became much more limited as it was integrated into the lives
of the local tribes and early settlers.
The taller sweet flag (A. calamus) species is generally
used as a filler plant to set off the more striking pond plants
in a plan. It is very underused, mainly due to its lack of availability.
Not having a significantly beautiful flower further reduces its
The sweet flag clan is certainly not known for its flowers.
Its all about the foliage when it comes to these little
sweeties. In addressing the flowers' style, they are club-like
in shape turning to a coffee brown as the summer wanes. Most
go unnoticed, especially on the smaller varieties, not something
to write home about.
A. calamus Variegatus >
Back to the common sweet flag. It is not considered a real
eye catcher. Its the variegated sibling A. calamus
Variegatus, variegated sweet flag, that can easily
hold its own in most waterways. If placed as a specimen plant
or as a mass planting, this beauty demands attention.
One aspect of this aquatic marginal that I really like is
its new growth as spring comes along. As previously mentioned
this species does lose its leaves in the winter, but what a sight
it is as it makes its return. Not only is it vibrant green and
white, but there is also a pink infusion of color that makes
having it in close proximity a must.
As the growing season moves along, sharing space with this
beacon can be very illuminating. The Colocasia genus,
commonly known as elephant ears or taro, makes great companion
plants for variegated sweet flag, especially 'Black Magic' taro.
The dark maroon leaves contrast extremely well against the white
and green sheen of the sweet flag leaves. I can also see blending
some Papyrus family members into the mix. Using the tried and
true umbrella palm (Cyperus alternifolius) is always a
summer enhancing experience. You can add even more to the scene
by injecting some purple hues such as powdery Thalia,
also known as hardy Canna (Thalia dealbata), or some of
the many purple water iris that are plentiful at most aquatic
Moving on to the A. gramineus collection, I need to mention
that I will primarily describe the better known varieties that
would most likely be found during a plant excursion, yet it should
be noted that there are a few other more obscure specimens out
and about that you may run across.
The foundation plant of this species is of course the dark green
and grassy looking Japanese sweet flag. It stays at about 12"
(31 cm) tall and forms a 12"-15" (31-38 cm) clump if
left to grow freely. A 1-2" (2-5 cm) water depth is all
they really need to be happy. The most fun we have at the nursery
is trying to distinguish it from A. gramineus Licorice
-- lots of sniffing and crumbling of the leaves to get to the
real truth. It becomes pretty evident as that anise aroma shows
A. gramineus Licorice
It truly is quite remarkable how similar they are besides that.
A couple of other forms that are similar in stature to the Japanese
sweet flag are A. gramineus Ogon and A.
The golden Japanese sweet flag (Ogon) is striped
with deep shades of yellow combined with a creamy white. This
is a good one to mix with black mondo grass (Ophiopogon planiscapus
nigrescens), (great aquatic but very slow), or Astilbes
and Japanese primrose when it is used as a well-watered terrestrial.
A. gramineus Ogon' >
The Variegatus Japanese sweet flag has typical
green and white variegation that may blend well with Lobelia
Queen Victoria or blue Medusa corkscrew rush (Juncus
spiralis Afro). Both the golden and the variegated
Acorus can add good foundation and depth to most pond
< A. gramineus
The last two of this clan are the smallest. The first, A.
gramineus Pusillus, is a dwarf version of the
common Japanese sweet flag, with dark green strap leaves. It
only reaches a height of 5"-6" (13-15 cm) while remaining
compact, not sprawling beyond those constraints laterally. That
makes it very good for small ponds and water bowls.
A. gramineus Pusillus >
A. gramineus Minimus
The second little gem, miniature golden Japanese sweet flag (A.
gramineus Minimus Aureus), is something to behold.
If ever there was a dwarf plant that works well in a table top
water bowl or even in a small floating island, this is it. It
only grows to a height of 2" (5 cm) and over time it will
spread to maybe 3"-4" (8-10 cm). Ive always thought
that by combining these bright yellow bundles with carnivorous
plants or with the dwarf corkscrew rushes, a perfect little world
can be created. Add in a little fairy dust and who knows what
might happen. These two mini sweet flags really prefer to be
saturated to a depth of no more than ½" (1 cm) or
to be kept constantly moist.
Sometimes as aquatic plant lovers we find certain plant lines
that can make our busy lives just a little bit easier. The Acorus
family falls into that sphere. The care requirements are fairly
simple. If the plants are given the correct water levels, trimmed
back a bit before springtime, given a light environment somewhere
between full sun and part shade (and dont put them in USDA
hardiness zone below 3 or above 11) you will be able to keep
these living on the sweet side for a long time.
At the nursery we occasionally run into some minimal insect
problems, mostly due to the fact that they are growing together
with so many other genera. In most ponds with the natural defenses,
its likely that all that could be needed is to sink them
under the water for a couple of days. Besides the ease in caring
for them, they are all propagated by division during the spring
and summer, even into the fall, if they can be protected through
the winter. They are exceptional plants, especially during the
propagation process, when you feel like you are working in a