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Sunday, 21 April 2013

Walking Irises: A case of mistaken identity - Neomarica and Trimezia

Walking Irises: A case of mistaken identity - Neomarica and Trimezia

Neomarica caerulea “Regina”
Ok we have had these plants for ages so in many ways it is an old friend. When I was a little boy we had them growing in the garden at Centipede Alley at Moto’otua. When we moved to Alafua they were dug up and transplanted there. I latter dug some up and transplanted them at Moto’otua and then to Vailele where they disappeared while I was away. I assumed they died out due to the place being on the coast but according to various sources they are drought and salt tolerant so maybe it was something else.  In any case it was not till around 2008 that I stumbled across a couple plants being sold under the Banyan trees on Beach Road in Apia and made arrangements to buy one after work.
Neomarica caerulea “Regina”
I planted that single plant at Malifa and as it grew and sent up offsets. I waited patiently until they were sufficiently big, then dug the whole clump up and divided it and replanted the individual plants. When I moved to Alafua I took some with me and planted them there again as the ones that had been left behind had disappeared.

Neomarica caerulea “Regina”
We always referred to this plant as a Blue Iris although later on I began to doubt the accuracy of this name. At Malifa there were some plants that looked like they were closely related to this since they resembled each other except for a number of differences.

Yellow Walking Iris flower
First of all the flowers were much smaller and yellow speckled with brown. Also they had many more flowers on long thin flower stalks. Indeed the whole presentation of the flowers was entirely different as you can see.
Blue and Yellow Walking irises (not to scale)
On top of that they had this bizarre tendency to grow little plantlets out of the flowers. These would grow and the weight of the growing plantlets would make the stalk bow down until it touched the ground and the plantlets took root. They also multiplied by sending up offshoots.

The Blue ones on the other hand at most had three flowers per stalk and sometimes these flowers developed seed pods although I have never successfully grew any seeds out of them ...  yet.
Neomarica caerulea "Regina"

The other difference compared to the Yellow flowered plant is that the Blue one had much larger and sturdier leaves and a slightly different centre rib structure. Other than these differences the flowers apart from size and colour were remarkably similar which to me indicated that they were related being at least of the same genus.
Leaf of Neomarica caerulea "Regina" showing centre rib
The close resemblance of the flowers and the tendency of the yellow one to grow plantlets led me to the Neomaricas otherwise known as “Apostle Plants” or “Walking Irises”.

The name “Walking Iris“ refers to the tendency of the plant to grow plantlets and “walk” across a lawn while the “Apostle Plant” reference alludes to the belief that they always have twelve flowers per stalk which I can confirm is NOT true.
Yellow Walking iris Flower and plantlets forming on flower stalk
The whole “Walking” thing is what still confused me because the Blue ones that I have and the Blue ones that I have seen on line do NOT “walk” at all. Interestingly one site (LINK) addresses this very issue noting that:

 “Although it is considered a walking iris, we have only seen it walk under extreme stress.”
That statement is extremely interesting and could perhaps point to a reason for the tendency for these plants to “walk” because when you think about it developing plantlets that will “walk” could be a way of the plant to try to ensure that it continues by growing in a location that is hopefully more favourable to the continuation of itself than if it just sent up another offset. The “walking” plantlet would end up taking root some distance away from the mother plant which in some cases might make a world of difference to its survival. But that is just my theory.

But getting back to identifying the Blue flowered plants, the closest that I have found that matches the Blue Irises I have is Neomarica caerulea “Regina”.

There are a number of other varieties which I assume are cultivars of Neomarica caerulea. However, Neomarica caerulea “Regina” is the one that I think is the one that we have had all these years.

The Yellow one I have tentatively identified as Neomarica longifolia which some identify as being synonymous with Trimezia martinicensis and given the common name of Yellow Walking iris. Trimezia is a genus which belongs to the same family as Neomarica – which is Iridaceae.

PHOTO of Blue Iris

As it is I picked up another variety from Tului Peters at Samoan Nursery up at Aleisa a few months ago. It is a smaller plant than even the yellow one and if I remember correctly it has white flowers. But has not yet flowered and seems to be growing very slowly. Actually the plant is rather small, being about 12 inches / 30cm in height. I am assuming that this is its full size because one of the two plants I obtained had a plantlet which you would only get from a plant that had flowered unless this is yet another variety that manages to “Walk” without having flowered first which I find  very unlikely since from what I have read, flowering is part of the process.

PHOTO of small Neomarica

Maybe it is a Neomarica northiana given how it is supposed to be white.  I guess we will have to wait and see what it flowers look like.

As for the identity of the Yellow Iris that are still uncertain. I did some research on the whole Neomarica longifolia versus Trimezia martinicensis issue and found some interesting information.

First of all due to the close resemblance between plants of Noemarica and Trimezia they are often confused and misplaced in the wrong genus or treated as synonymous.

However, according to information from the Kew Royal Botanical Gardens citing Chukr & Giulietti (2001), there are distinctive vegetative characteristics that distinguish the genrea which are more accurate than looking at the flowers alone.

These are summarised as follows:
With regards to the Underground system Trimezia ALWAYS has a corm while Neomarica has a rhizome in 90% of the species and a corm in only 10%.

For the leaf bases (cataphylls) Trimezia has it’s cataphylls arranged in a spiral while Neomarica has it’s cataphylls arranged in a plane with the base of one clasping the one above
Leaf base of neomarcia caerulea
For the leaves Trimezia has flattened or circular leaves while Neomarica has leaves that are sword-shaped folded lengthwise

For the flowering stems (scape) Trimezia has circular in cross section and never leaf like while Neomarica has a flattened and leaf like flowering stem.
Flowering stem of Yellow Walking iris

Flowering stem of Blue Walking iris
Taking this information into account I think that the yellow irises that I have are actually a Trimezia. I indicate the genus only because I discovered that there are two species of Trimazia that match the description of the ones I have; T. martinicensis and T.  steyermarkii

So now I need to figure out if it is Trimezia martinicensis or Trimezia steyermarkii.
... to be continued


  • Family: Iridaceae – Genus Neomarica – Species: Neomarica caerulea
  • Family: Iridaceae – Genus Neomarica – Species: Neomarica longifolia
  • Family: Iridaceae – Genus Neomarica – Species: Neomarica northiana
  • Family: Iridaceae – Genus Trimezeia – Species: Trimezia martinicensis
  • Family: Iridaceae – Genus Trimezeia – Species: Trimezia steyermarkii,
Medical use
No information found

Glossary: PLEASE NOTE I will be updating the post to include the glossary as soon as I have completed it

References PLEASE NOTE I will be adding all the references and links to the on line source as soon as possible
Agristarts Entry on Iris Neomarica caerulea “Regina” LINK

Fairchild Tropical Botanical Garden Entry on Neomarica caerulea LINK
Kew Botanical Gardens LINK
Wikipedia Entry on: Iridaceae
Wikipedia Entry on: Neomarica
Wikipedia Entry on: Trimezia

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  1. Dear Vincent,
    Thank you very much for the nice cover from Samoa that you have sent to me, which I have received today. If you wish, you can see their picture at my blog:

    I send you again my sincere wishes of health and happiness to you, your family and friends.

    A hug from Spain

    Emilio Fernandez

  2. Dear Emilio,
    You are very welcome. I am glad you got the letter and stamps.
    Hugs from Samoa,

    Vincent Vermeulen