Indian Corn Cob, Corn Cob Plant, Corncob Euphorbia, Corncob Cactus
Synonyms of Euphorbia mammillaris (8) (Updated on 8-21-21 from Plants of the World Online): Euphorbia enneagona Haw., Euphorbia erosa Willd., Euphorbia fimbriata Scop., Euphorbia latimammillaris Croizat, Euphorbia platymammillaris Croizat, Euphorbia scopoliana Steud., Treisia erosa (Willd.) Haw., Vallaris fimbriata (Scop.) Raf.
Euphorbia mammillaris L. is the correct and accepted scientific name for this species of Euphorbia. It was named and described as such by Carl von Linnaeus in the first edition of Species Plantarum in 1753.
Carl Linnaeus is also credited with naming the Euphorbia genus and described it in the first edition of Species Plantarum in 1753.
Plants of the World Online lists 1,995 species in the Euphorbia genus (as of 8-21-21 when this page was last updated). It is a member of the plant family Euphorbiaceae with 227 genera. Those numbers could change as updates are made on POWO.
The genus, and family for that matter, consists of plant species from most of the world. While some may not be that abundant, others are quite common. There are herbaceous plants (annuals, perennials, wildflowers, herbs, etc.), trees, shrubs, and succulents in the genus. Euphorbia mammillaris is a succulent species, almost cactus-like, from South Africa. Yeah, I know… Cactus are succulents, but not all succulents are cactus… 🙂
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I picked up this Euphorbia mammillaris cutting on March 29, 2019. I have had a few other Euphorbia species as companions and we have always gotten along very well. I like the small leaves and there were remnants of its small yellow flowers when I brought it home.
Origin: South Africa
Zones: USDA Zones 8b-11 (15-40° F)
Size: 6-18” or “more” tall. HMMM…
*Light: Sun to part shade
**Soil: Very well-draining soil. Potting soil amended with additional pumice or chicken grit and perlite.
**Water: Regular watering during the summer. Very little, if any, during the winter.
*During the summer, I keep most of my cactus on the back deck where they receive full sun. I keep the Wephorbia mammillaria on the front porch during the summer where it gets light topart shade (depending on the time of day). During the winter most cactus aren’t picky about the light because they are basically dormant. For several winters, mine were in front of the east-facing sliding door in the dining room so they didn’t get much light. I built a new shelf for the bedroom so now they are in front of a west-facing window. The Euphorbia mammillaris and most of the other succulents are on a shelf in a south-facing window in a cool bedroom.
**I used 2 parts Miracle Grow Potting Soil with 1 part additional perlite and 1 part chicken grit for many years. I started using a 50/50 mixture of Miracle Grow Potting Soil and pumice in 2018 with favorable results. I also use Schultz Potting Soil which has fewer chunks of bark. I purchased the pumice online from General Pumice but you can get smaller quantities on Ebay. The problem with Miracle Grow and other peat-based potting soil is that once it gets dry it doesn’t absorb water very well. So, during the winter months, the mixture can become hard. Sometimes I repot in the fall with a fresh mixture so the potting soil will be loose for the winter. The timed-release fertilizer in the potting soil won’t be activated until you water anyway. Pumice also has nutritional value. Cactus and succulent enthusiasts recommend not to use peat-based potting soil, but around here that is difficult to find. I haven’t tried coir yet… There is a lot of cactus and succulent recipes online and you just have to experiment to see what you and your cactus like.
***I water my cactus and succulents on a regular basis during the summer but barely ever in the winter (maybe a little in January) until close to time to take them back outside.
This species has 7-17 ribs with hexagonal tubercles in vertical rows resembling an ear of corn. It also has a few spines. The tubercles swell with normal watering and shrink during dry periods.
There is not much information online about the Euphorbia mammillaris for some reason. It is a very interesting plant in my opinion.
The Llifle (Encyclopedia of Living Forms) website has more than any other website about this species and growing recommendations.
Although most information online says this plant grows up to maybe 18″ tall, Llifle also says…
“…young plants are happy growing indoors, where they can easily reach the ceiling.”
“It is a moderately fast grower, and will quickly become large landscape masterpieces in just 3-5 years.”
SOOOO… It will be interesting to see what this plant does first hand.
Description: It is a short-stemmed dioecious shrublet producing a dense cluster.
Stem: Thick deep green,, erect, simple and ribbed, that in cultivated plants may branch above, 1, 5-6 cm in diameter.
Mature: Height 20-35 cm tall. Usually, there are many club-like lateral branches, starting about 10 cm and arches upward.
Ribs: 7-17, with hexagonal crowded tubercles set in vertical rows after the manner of an ear of corn and separated by horizontal groves.
Spines: Occasionally present and scattered, thick, blunt, and whitish, up to 1 cm long. The “spines” are the solitary sterile peduncles.
Leaves: Small, ephemeral (meaning they last for a short time).
Flowers: Produces yellow solitary cyathia at the top of each stem. Peduncle +/- 2 mm long with several bracts up to 3 mm long. Nectar glands elliptic, separate, yellow-green to purplish.
Blooming season: Late winter to early summer.
Fruits: Obtusely lobed, up to 6 mm in diameter, subsessile.
Remarks: Euphorbia fimbriata is similar to E. mammillaria but has conical stem tubercles.
I had to move the potted plants inside for the winter on October 11 (2019) because an “F” was in the forecast. As always, I photograph and measure the cactus and most of the succulents. The Euphorbia mammillaris measured 5 3/4″ tall. I didn’t measure it when I first put in the potting soil so I have nothing to compare it to. I do know it is growing, though.
There are a lot of leaves on the upper part of the stem which will fall off at some point. Their leaves are ephemeral which means they only last for a period of time but they will regrow when the time is right. That makes it interesting to grow this plant.
I am kind of running out of words to say…
Oh, the spines… It does have a few spines toward the base of the plant and side branches.
I had to bring the plants inside for the winter on 10-15-20 because an “F” was in the forecast. As always I took photos and measurements. The main stem of the Euphorbia mammillaris measured 8″ tall so it is doing quite well.
I really like the combination of leaves and thorns.
The Euphorbia mammillaris has grown from 8″ tall to 11 3/4″ tall since last October 17. It is 6″ taller since October 2019. I will admit it looks weird the way the stem is wide, then thin, then wide again.
Even though it is somewhat weird, it is still a neat plant.
I will continue to add more photos and information as time goes by.
Be sure to click on the links below for further information about growing this plant. Llifle has a lot of good information. There is also a variegated form of this species.
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.