Xanthosoma robustum OR sagittifolium on 8-13-18, #495-5.
Capote
Xanthosoma robustum
zan-tho-SO-muh roh-BUS-tum
OR…
Malanga, Arrowleaf Elephant Ear, Etc.
Xanthosoma sagittifolium
zan-tho-SO-muh sag-it-ee-FOH-lee-um
Xanthosoma robustum Schott was first described by Heinrich Wilhelm Schott in Oesterreichisches Botanisches Wochenblatt in 1853. No synonyms listed on Plants of the World Online.
OR…
Xanthosoma sagittifolium (L.) Schott was named and described as such by Heinrich Wilhelm Schott in Meletemata Botanica in 1832. It was first named and described as Arum sagittifolium by Carl von Linnaeus in the second edition of Species Plantarum in 1753. Plants of the World Online by Kew listed 40 synonyms of this species when I updated this page on 11-14-22).
The genus, Xanthosoma Schott, was also named and described by Heinrich Wilhelm Schott in Meletemata Botanica in 1832.
As of 11-25-23 when this page was last updated, Plants of the World Online by Kew lists 198 species in the Xanthosoma genus. It is a member of the plant family Araceae with 142 genera. Those numbers could change as updates are made on POWO.
It is very interesting how I came to have this Xanthosoma robustum OR X. sagittifolium as a companion. When my sister came down from the city to go plant shopping at the local Amish greenhouses in the spring of 2017 I found a Colocasia gigantea ‘Thailand Giant’. I brought it home and it did very well. I stored the rhizome overwinter in the basement. It did fine until just about time to plant the Colocasia the next spring when I noticed it had rotted. So, when my sister came again in 2018, when we went plant shopping, I checked with the same greenhouse and he said he got his order in too late and the supplier had run out of Colocasia gigantea ‘Thailand Giant’. So, I checked several reliable sources online but didn’t want to pay some of their prices. I found a listing on Ebay for rhizomes… Well, the name is Leucocasia gigantea now.
I will admit I thought that was a bit strange since every other source was selling plants grown from tissue culture. His listing said the “bulbs” he was selling were “from” the Wellspring strain. I assumed he was talking about Wellspring Gardens which is in Florida. I had bought A LOT of plants from Wellspring in the past (starter plants) including a Colocasia gigantea ‘Thailand Giant’ in 2012. I messaged the seller on Ebay and after he replied I ordered a rhizome from him. I think I ordered partly out of curiosity. He later said he had shipped me the largest bulb and even lost money due to shipping fees.
Although I am using the name Leucocasia gigantea ‘Thailand Giant’ in the story below, you will see why if you continue reading. It is because that is what I thought it was until I posted photos on the International Aroid Society Group on Facebook on September 16 (2018)… I had previously found out the name Colocasia gigantea had changed back to Leucocasia gigantea. I changed the name in the photo captions, though…
The arrival of the new Leucocasia gigantea ‘Thailand Giant’ bulb on 5-22-18, #447-9.
The new Leucocasia gigantea ‘Thailand Giant’ rhizome arrived on May 22. The package was wrapped in a newspaper with Chinese writing.
The newspaper was the Epoch Times from Atlanta, Georgia. I thought that was interesting so I had to check it out. The Epoch Times was founded in 2000 in New York City by a group of Chinese-American Falun Gong practitioners. The newspaper is either sold or distributed free of charge in 35 countries in 21 languages. The founders say they were responding to censorship inside China and a lack of international understanding about the Chinese repression of Falun Gong. The newspaper can be read online and receives 105 million page views per month from 20 million visitors. Anyway, the Wikipedia article and the newspaper’s website are quite interesting.
I unwrapped the newspaper and found a box…
Inside the box was an envelope…
I opened the envelope to find a, umm, sweet potato? Well, it sure looks like the white sweet potatoes I grew in 2016.
The supposed Leucocasia gigantea ‘Thailand Giant’ rhozome on 5-22-18, #447-15.
Right off the bat, I thought something was strange. It looks nothing like what I expected, though. I expected it to look like a rhizome similar to the Colocasia esculenta and judging from the rhizome that grew from the ‘Thailand Giant’ I grew last year. It looks similar to the offsets that grow from my Colocasia esculenta only MUCH, MUCH larger.
Leucocasia gigantea ‘Thailand Giant’ coming up on 6-3-18, #452-9.
I planted the Leucocasia gigantea ‘Thailand Giant’ RHIZOME in the north bed a little farther over than I had planted the one last year. I had previously moved the Hosta ‘Empress Wu’ farther away from the corner and the new TUBER is to the right of it. I noticed this sprout coming up on June 3.
NOT a Leucocasia gigantea ‘Thailand Giant’ on 6-14-18, #459-44.
The new plant started growing and was off to a good start. You can see in the above photo taken on June 14 that its second leaf has emerged. As you can see, if you know anything about Colocasia, something is a little weird…
Xanthosoma robustum OR X. sagittifolium leaf on 7-4-18, #469-27.
I was looking at this leaf on July 4 and taking notice of how different it looked compared to the Colocasia and Alocasia leaves. It was also different than the Leucocasia gigantea ‘Thailand Giant’ leaves from 2018 and 2012… Hmmm…
Xanthosoma robustum OR X. sagittifolium on 7-6-18, #471-9.
Looking good and doing well… Ummm… I didn’t notice at first, and not until I looked at this photo, but there is something strange about the petiole where a new leaf is beginning to emerge. Sometimes when I am taking a lot of photos, I don’t notice everything.
Xanthosoma robustum OR X. sagittifolium on 7-23-18, #484-1.
While I was mowing on July 23 I was stopped dead in my tracks when I saw the new leaf. I am always anxious for new leaves to start growing because each new leaf grows larger than the one before it. But this leaf was completely different…
Xanthosoma robustum OR X. sagittifolium variegated leaf on 7-23-18, #484-2.
IT’S VARIEGATED!!!
I have seen a few different Alocasia and Colocasia cultivars online that are variegated, but never any photos of a variegated Colocasia gigantea ‘Thailand Giant’ (I mean Leucocasia). This is completely weird! How could this Leucocasia gigantea ‘Thailand Giant’ produce a variegated leaf? And what the heck about the top of the leaf! Hmmm… Something is definitely weird…
Xanthosoma robustum OR X. sagittifolium 7-29-18, #487-66.
Well, by this time I was completely confused!
Xanthosoma robustum OR X. sagittifolium on 8-13-18, #496-5.
If it were a Leucocasia gigantea ‘Thailand Giant’ it would be MUCH taller by now.
Xanthosoma robustum OR X. sagittifolium on 8-26-18, #499-24.
I couldn’t take it anymore so I posted photos of this plant on the group called International Aroid Society on Facebook.
Xanthosoma robustum OR X. sagittifolium on 8-26-18, #499-25.
One of its members, Robert McCracken, promptly said it was a Xanthosoma sagittifolium. We sent a few replies back and forth several times…
Xanthosoma robustum OR X. sagittifolium on 9-13-18, #508-10.
Later, I had a few questions about storing this plant for the winter. I had never grown a Xanthosoma before so was curious about its winter treatment. Do I dig it up and store it in a pot in the basement like the Alocasia? Do I let it get frostbit like the Colocasia esculenta then dig the rhizome and store it? So, I messaged Robert again… This time, he heard me message him and we chatted for a very long time.
Xanthosoma robustum OR X. sagittifolium on 9-13-18, #508-11.
Also, once I found out this plant was a Xanthosoma instead of a Leucocasia gigantea ‘Thailand Giant’, I contacted the seller on Ebay. I told him what I had found out and sent him a lot of photos showing him the difference. He said he noticed “one shipment” where the “bulbs” were lighter in color… Well, folks, I don’t really buy that story. His same listing was STILL on Ebay as before the last time I checked. I am not saying that all the rhizomes he is sending out are Xanthosoma instead of Leucocasia gigantea (which he is still calling Colocasia gigantea), but the batch mine was from was not Leucocasia gigantea ‘Thailand Giant’. So, no doubt, a lot of people who thought that they were growing Leucocasia gigantea ‘Thailand Giant’ actually have Xanthosoma… That’s how so many people misname their plants. Then when they pass them along to others, the wrong name passes along as well.
Xanthosoma robustum OR X. sagittifolium on 9-19-18, #509-1.
Robert also said he was mistaken. He said instead of this plant being Xanthosoma sagittifolium it was either a Xanthosoma atrovirens or Xanthosoma robustum. He said X. sagittifolium doesn’t grow variegated leaves but X. atrovirens does… But, the X. robustum doesn’t spread out like this plant is. He also said that it was an X. sagittifolium I would have a lot of offsets…
So, I did a little research… Robert had given me several links about the Xanthosoma genus and many species.
Xanthosoma robustum OR X. sagittifolium on 9-19-18, #509-2.
According to Plants of the World Online, Xanthosoma atrovirens is now a synonym of Xanthosoma sagittifolium. So, I guess Xanthosoma sagittifolium produces variegated leaves after all.
Xanthosoma robustum OR X. sagittifolium on 9-19-18, #509-3.
One of the key features of the Xanthosoma, as shown in the above photo, is how the top part of the leaf goes clear down to the apex (where the petiole attaches to the leaf). Remember, the petiole is what you may refer to as a “stem”. It is correctly called a petiole and not a stem. Notice the width between the edges of the leaves (now, I don’t even know what you call it).
Xanthosoma robustum OR X.sagittifolium on 9-19-18, #509-4.
The leaves are very thick and the “seam” around the leaf edge act as a gutter to drain water.
Xanthosoma robustum OR X. sagittifolium on 9-19-18, #509-5.
The midribs are very pronounced, more than on the Colocasia and Alocasia (at least the ones I grow).
Xanthosoma robustum OR X. sagittifolium on 9-19-18, #509-6.
Xanthosoma robustum OR X. sagittifolium on 9-19-18, #509-7.
Even the petioles have variegation…
Xanthosoma robustum OR X. sagittifolium on 9-19-18, #509-8.
The leaves on top of the plant are nearly horizontal and cupped toward the apex…
Xanthosoma robustum OR X.sagittifolium on 9-19-18, #509-9.
NICE! The leaves are very dark green and have a bright shine to them…
Xanthosoma robustum OR X. sagittifolium on 10-5-18, #516-10.
All I can say is that this is an AWESOME plant!
Xanthosoma robustum OR X. sagittifolium on 10-10-18, #519-81.
I am not upset that I was sent something I didn’t order. It was sure a good way to have experienced such a magnificent plant.
Xanthosoma robustum OR X. sagittifolium roots on 10-14-18, #521-1.
I had been putting off the inevitable for long enough. I had chatted with Robert again and he suggested not to let it get frostbit. So, when the “F” was in the forecast, I had to dig up this plant… As with the Alocasia and Colocasia, they really don’t have a massive root system. One might think they would judging by the size of the plants…
Xanthosoma robustum OR X. sagittifolium roots and offsets on 10-14-18, #521-2.
Well, it does have three offsets they just hadn’t made it to the surface yet. No doubt, in a warmer zone with enough time, they would have made it to see daylight.
Xanthosoma robustum OR X. sagittifolium in a pot for winter on 10-14-18, #521-3.
Since I was just putting the Xanthosoma in a pot for the winter I didn’t need a HUGE pot. I know, it looks weird… Believe it or not, this plant is 60″ tall and 80″ wide!!! I was wondering how in the heck I was going to get it through a 32″ wide door? When I repot the Alocasia, which I keep in pots (except for the three I experimented with) I always put 3 stakes in the pot and tie the plants to them. They grow vertically and they need support until their roots grow to stabilize them. This one is different… No growing straight up about it!
Well, since it was standing up on its own in the pot, I thought maybe I could carry it and it would stay that way. Well, that didn’t happen. On the way down the steps of the back porch, the plant fell right out of the pot! GEEZ! So, I took the pot to the basement and repotted the plant there. I put it in front of the Alocasia that were already in the basement. The Alocasia, even though there are several, don’t take up as much room as the Xanthosoma did.
When I moved the plant to the basement, the idea was to get it to go dormant for the winter so I didn’t give it any water. The last time I checked on October 31, the Xanthosoma is still like it was when I took it to the basement.
The Xanthosoma rhizome didn’t survive the winter and I haven’t bought any more since…
I would really like another one… Maybe I can buy another one by accident from the same seller on Ebay…
I hope you enjoyed this page and maybe found it useful. If you have any comments, questions, or suggestions, I would like to hear from you. Please click on “like” if you visited this page. It helps us bloggers stay motivated. 🙂 You can check out the links below for further reading. The links take you directly to the genus and species of this plant. If you notice I made an error, please let me know.
The Belmont Rooster 
This is very interesting! But I’m wondering now whether Sagittifolium and Robustum are the synonyms for the same plant? According to Tropicos, Sagittifolium is a synonym for Roseum which is a synonym for Robustum… But the site doesn’t show Robustum as a synonym for Sagittifolium? What do you think?
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Hello Robin! Both Xanthosoma robustum and X. sagittifolium are accepted names. It is interesting that X. roseum is listed as a synonym for both species on Tropicos. Thanks for pointing that out because I hadn’t noticed. I checked to see if maybe the author’s name was different but it is the same. I checked with Plants of the World Online and they list X. roseum as a synonym of X. sagittifolium. Currently, they don’t list any synonyms of X. robustum… I will email my contact from Tropicos to see if they goofed. Take care and thanks for the comment.
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Help! I moved to California, into a rental about 6 months ago that had lots of, what I think are the xantho plants, in the backyard. I am from a different state and had never seen this plant before so it took me a few months to even figure out what it is. Now almost all of the plants are dead or dying. Everything I read just says to water them often. I do not have a green thumb and I have no idea what “often” means. I first tried to water them every few days, and they started turning brown, so I started watering them more often. We got lots of rain in the months of December and January so I only watered when it didn’t rain for a few days. When I check the soil it is very moist but the plants are wilted and turning yellow and brown, and all the “fullness” of the plants is gone. I have been feeding them every couple of weeks also. Can you tell me exactly how often to water them? I appreciate any help or advice that you can give me!
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Hello Susan! Well, you don’t need to water them so often. Likely, once a week during the summer is fine, but the rest of the year I wouldn’t even do it that much. I don’t know where you are from in California so I don’t know how much rain you get and when. Even though Xanthosoma are rainforest plants, too much water at the wrong time can cause their rhizomes to rot. Every plant has a dormacy (or pseudo-dormancy period. Once I bring my Alocasia into the basement for the winter they don’t get any water until I take them back outside again in the spring. Of course, basements are somewhat damp and it is 65° F down there.
So, stop watering them and check the rhizomes to see if they are still firm. If they are rotting (mushy) then they have started to rot. You can dig them up and see if part of the rhizome is still firm and wash off the rotted part. I think someone told me to use cinnamon to prevent the rest from rotting… Anyway, don’t water them anymore until they start to sprout.
Now, mind you, we live in completely different climates where I have to bring my aroids in for the winter and I grow my Alocasia in pots… I have yet to successfully overwinter Xanthosoma…
I hope this helps! Take care and good luck.
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