Bamboo Orchid, Arundina graminifolia
What you see on the left are a stand of what we call soil orchids, some of which have been beaten to the ground by heavy rains, and on the right a stand of robust Curcuma (locally, resurrection plant) leaves. The orchids have been straining toward the light for some time – we had no idea the Curcuma would cast so much shade when we planted it there – and the rains just helped them plunge on down to the ground.
The orchid stems can grow to 3 meters tall, and the flowers are at the very top, so their gradual leaning over the past week or so gave me the chance to take some images of the lovely flowers.
Panama is home to no doubt hundreds of species of native orchids, and Potrerillos has a particularly fine climate for them, but the first orchid I decide to write about, this one, was introduced from Asia! My excuse is that this orchid is highly conspicuous, being very popular as a cultivated plant. It’s been introduced to Puerto Rico, Costa Rica, Guatemala, and Panama, according to wikipedia, for this purpose. I had to wonder what the chances were that it would become an invasive plant.
If you don’t live in our neighborhood, and you’ve seen these orchids, you may very well know them as “bamboo orchids.” They are reminiscent of bamboo, with their reedy stems, formation of large clumps, and fairly tall size. Their scientific name is Arundina gramnifolia.
- Arundina comes from the Latin arundo, meaning reed,
- and gramnifolia means grass-like leaves (botanary).
So let’s take a closer look at these reedy stems and grass-like leaves.
If you saw this plant without its obviously-orchid flowers, how would you know it was not a bamboo or some other member of the grass family?
- The leaves are long and narrow – like grasses
- The leaves have sheaths that clasp the stem – like grasses
There are, actually, quite a few differences in the leaf structure between the orchid and the grasses if you look closely, but the easiest way to tell this plant is not a grass is by checking its stem.
- Grass stems are hollow.
- This stem is quite solid.
By vegetation alone, then, we can see that it is not a grass. It’s the flowers that tell us it is an orchid.
Arundina flowers
Even though we usually see only one flower at a time at the tip of a tall stem, the flowers occur in clusters, though of not more than 10. You can see the buds for new flowers here.
Arundina flowers, like all orchid flowers, have an outer whorl of 3 sepals and an inner whorl of 3 petals. The petals and sepals generally look so much alike that in the orchid world both sepals and petals are called tepals.
In the images below the flower is face down. The sepals are labeled in the left image and have been removed in the right image. (Click on either image for a larger view.)
When you remove the 3 sepals, you are left with 3 petals, but it looks like 2 petals plus another flower! This is a characteristic orchid structure. The middle petal is called the labellum, or lip, and it is always different from the others and larger than the others. It ends up at the bottom of the flower and provides a platform for orchid pollinators (wikipedia).
The next two images show (at left) the petals turned over so you can see the labellum and (at right) the labellum opened up so you can see the yellow-streaked platform highway for the pollinators. (Click on either image for a larger view.)
Okay, then what is that phallic-shaped space module in the middle of the labellum? Oddly enough, it’s, to oversimplify a bit, the male reproductive part of this orchid – the column that carries the packages of pollen, the pollinia, discussed recently here. Without consulting an expert, I’m certainly not going to try to label the parts of this incredible structure, but I think the pollinia are stored in the little cap-bill of the column pointed to by the arrow.
At least, when I touched that part of the column with my finger-tip, it fell off fairly easily. If the pollinator has followed that yellow streak pathway up toward the column, it wouldn’t take too much effort for that cap-bill to detach from the orchid and attach to the pollinator, in my viewpoint, anyway.
So, what pollinates Arundina, and what does the pollinator get in return?
From a study in Puerto Rico, where Arundina graminifolia has become naturalized, and also from Zuchowski in Costa Rica, I would expect bees to be the pollinators here in Panama. However, at the time I was taking pictures, anyway, I saw only ants, some other tiny unidentified insects, and this lightning-bug type guy.
I wasn’t sure the bug was serious, but pretty soon, I saw this:
There he is, traipsing right up the pollinator highway. And what will he get for his efforts? Well, no nectar, that’s for sure. Arundina is what is known as a “rewardless” orchid. Perhaps in this case, fair is fair, because it’s hard for me to see how those pollinia would find a surface on this insect’s body, anyway.
Is Arundina gramnifolia invasive here?
Getting back to that original, idle question – it turns out that this “rewardless-ness” is one of the reasons this exotic plant from Asia may never become an invasive species here in Central America. Studies in Puerto Rico showed that although Arundina graminifolia had become naturalized there, the infrequency of pollinator visits (no nectar reward, why visit?) meant infrequent fruiting and therefore the orchid spreads in its new environment at a rate similar to native species.
Guilt-free exotic plant gardening!
Hi, A lovely, attractive orchid for the garden. You explained so well its merits, how it grows etc. I grow some Orchids, easy ones! like Dendrobiums. I have also a very tall Vanda growing up a tree and sending down long roots. Very interesting plants, Orchids. I do like them and think they are beautiful but I have never been absolutely captivated by them. I always think of them as spoilt damsels wanting all the attention and I am never sure is it the right one!
Hi Titania,
Thanks for dropping in and commenting. Yes, orchids are a world into themselves and I’m amazed at the patience of those who become hooked on growing and cultivating them. Such ardor!
Here, the Arundina is the only orchid in our “garden,” but we do have many orchids growing wild in the trees. The spoilt damsel attribute more or less vanishes here in their natural setting.
Thanks for the great, detailed post on this plant! Here in Southern California a few orchids will do fairly well in the ground, and this is one of them, even with our occasional frosts. A neighbor has some and they’re pretty dramatic when they do their thing! Hmmm…maybe time to plant some of my own…
Hi James,
Nice to hear from you and to learn that Arundina does well in Southern California. They can indeed be very dramatic – especially in full sun.
I’m seriously considering moving our entire, small, stand, which I’m sure they would appreciate.
Very nice article.
We have planted 35 or so Bamboo Orchids in the garden areas of our yard. We live in South florida so the climate is perfect for them. The stems leaves and flowers are a beautiful thing to behold.
Do you recommend a specific blend of fertilizer for them? We would like to encourage continued flower growth throughout the year.
Thank you:
Mark
Hi Mark,
Sorry for the delayed response – we’ve been without internet for a few days.
It happens that these Bamboo Orchids are growing in one of the few fertile-soil areas on our property, so we have given them no special care. They do not, however, bloom year-round, so I’m afraid I’m not much help to you.
One thing I should mention, though, is that they need more direct sunlight than they have at our place, and we’ll probably move this plant when we have nothing more urgent to deal with. As it is, they tend to lean into the sun.
Nice to hear from you.
Mary
I just bought three beautiful bamboo orchids and
I am planning to plant them around my swiming
pool. We live in SOUTH fLORIDA.
Will it be better to plant them on the ground or
put them on big planter .
Will appreciate your advice .
Thank you.
SM
Hello Simeon,
All I can tell you is that everyone here in Panama grows their bamboo orchids in the ground. Your vendor or your local garden club could provide you with a better answer than I can for South Florida. Good luck with it and do enjoy! It’s a beautiful and interesting plant.
Mary
[...] info on bamboo orchids: Arundina graminifolia – Wikipedia, the free encyclopedia Bamboo Orchid, Arundina graminifolia | A Neotropical Savanna [...]
Hi, Just bought 2, live in south florida, the hang tag says to mix humus and bark with mother earth then plant. Cannot find humus don’t know what they are talking about. Help please.
Geri
Geri,
Humus is decomposed organic material mixed with soil. It’s fertile black dirt, in other words. If you can’t find a source of humus, try potting soil. The truth is, though, these bamboo orchids of mine are growing in relatively poor soil, and I certainly did not add bark to it before planting. So if your garden soil is half-way decent, you can probably plant them directly into it.
Good luck!
Mary
Thanks for your very insightful information. I am visiting a friend in Tampa Fl central west coast area and they have your orchid and it seems to be doing well. This plant stands about three feet tall and is in full bloom. It does get some what cool here so they cover it at night. I will be visiting again and will give an update. Happy upcoming holidays.
Hi Mary,
wonderful, that you took the time to inform us so lovingly about the Bamboo Orchid!
Bought one at Driftwood Garden Center in Florida and it reads: “full/part sun – moderate water – season all year – fertilizer 6-8-10 – full sun orchid, good in the ground or in containers”
Happy gardening!
Hi Mary
We live in Pinetown, KwaZulu Natal, South Africa. I have owned and loved an arundina graminifolia for some fourteen years. It was given to me as a pot plant which went with us each time we moved.
It has been divided a few times over the years and seems a little sad now. I was hoping to find some secret in your comments but it seems that it is one of those plants to be loved and left in the ground.
I don’t know if this will reach you, but I really enjoyed your article.
Wendy
PS My husband grows Cymbids, Pafs, Dendrobiums, Vandas, and three or four indigineous orchids in the garden … and loves them all.
Hello Wendy,
Thanks so much for commenting. I’m sorry to hear that your Arundina is sad these days, and I wish I could be of help, but I have no idea what to do. If anyone else reading this post has any ideas for Wendy, they’d be greatly appreciated.
Mary