House guests for the winter

This year saw the addition of a number of tender plants to my succulent collection. For the first time ever, I’m forced to overwinter plants inside the house since I don’t have a greenhouse or conservatory. Most these are “fat plants,” a category made up of caudiciform and pachycaul plants. “Caudiciforms” have a swollen base or enlarged underground stem (known as a “caudex”). “Pachycauls” have a thickened or swollen trunk.

All fat plants hail from warm climates, necessitating winter protection. Some of them might be hardy enough to spend the winter outside, but I’m not taking any chances since they’re still small. Others need temperatures consistently above 55°F. This is new territory for me and I still have a lot to learn. However, my fascination with these odd plants is so strong that I’m willing to go the extra mile to give them what they need to survive and hopefully thrive.

Here are the plants that are spending the winter near the large window in the loft. This window faces west so it doesn’t receive as much sun in the winter as it does in the summer. However, there are also three south-facing windows to the left that provide extra sunlight.

House guests huddling near the large upstairs window

Since most of these plants are quite small, they don’t look like much. At first glance you might wonder why I would want to collect something so plain or uninteresting. For this reason, I’ve added photos of larger specimens, either in the wild or in cultivation. At least you’ll get a better idea of the potential these plants have, even though few of them will ever get to the size they would reach in their native habitat.

LEFT: Sinningia tubiflora (click here to see a blooming specimen)
MIDDLE: Pachypodium namaquanum
RIGHT: Adenium obesum

▶ Pachypodium namaquanum

In its native habitat in South Africa and Namibia, Pachypodium namaquanum can grow to 12-15 ft. in height. The tapering trunk is studded with spines that give it a textured look. According to Wikipedia:

Seen from a distance, the plant has the appearance of a person trudging up a slope whence its common name of "Halfmens" (Afrikaans for 'semi-human').

My small Pachypodium namaquanum

                                                                                                                                    
 

Pachypodium namaquanum in its native habitat
© Graham, onestonedcrow.blogspot.com. Reproduced with permission.
Click here to visit Graham’s fascinating blog from Namibia.

▶ Pachypodium succulentum

My second pachypodium, Pachypodum succulentum, is also native to South Africa. It is supposed to be able to withstand light frost, so I may leave it outside next year. Collectors grow it not only for its caudex but also for its attractive flowers that can range from pink to crimson (see the 2^nd photo below).

My Pachypodum succulentum

Photo source: Wikimedia Commons

▶ Adenium obesum

The best-known caudiciform is the desert rose (Adenium obesum). While not completely mainstream, it’s not a rarity either. I sometimes see it for sale at the garden centers of the big home-improvement chains, or even at Walmart. In recent years Adenium obesum has been heavily hybridized to create new flower colors and shapes, such as double flowers. It is particularly popular in India, Thailand, and Taiwan. Check out this interesting article on the adenium industry in Asia; this site also has useful cultivation information.

I have two desert roses. One is small (in a 4-inch container) but with a relatively fat caudex.

My Adenium obesum, small but fat

The other is much larger overall, with larger leaves but a smaller caudex. But plants are dropping leaves right now, entering a phase of semi dormancy. The biggest threat at this stage is overwatering which might lead to rot, so I’m being careful.

My other Adenium obesum, taller but with a smaller caudex

Adenium obesum is indigenous to eastern and southern Africa and parts of Arabia. In its native habitat (see photo below) it can reach heights up to 12 ft. but in cultivation it’s much smaller. 

Photo source: http://www.thegorgeousdaily.com/adenium-obesum/

The desert rose has attractive flowers that can be shades of pink, red, white, or a combination thereof. Supposedly they can flower anytime of the year, although spring and fall are more typical. They prefer sunny—even hot—spots and can take a lot of water when actively growing. In the winter, they need to be kept on the dry side, especially when they drop their leaves. This holds true for all fats plants described in this post.

Photo source:  Wikimedia Commons

▶ Fockea edulis

Fockea is a genus of caudiciform plants native to South Africa and Namibia. In situ, the caudex can be up to 2 ft. in diameter and is usually completely buried. In cultivation, the caudex is raised for display purposes. When actively growing, fockeas produce vines that can grow to many feet (one source says up to 12 ft.). For older plants, a support needs to be provided. My Fockea edulis is small so I just let the vines scramble up the window.

Fockea edulis (on the right)

This is what a larger specimen looks like. The caudex is very impressive.
Photo source: Cactuspedia, one of my go-to sources for high-quality information and photos about succulents

▶ Dendrosicyos socotrana

Dendrosicyos socotrana is a bottle tree only found on the island of Socotra off the coast of Yemen. It’s common name is “cucumber tree,” alluding to the fact that botanically it’s a member of the Cucurbitaceae (or cucumber) family. In its native habitat, this pachycaul can grow to 18 ft.

I got my specimen from the UC Davis Arboretum which has had a great track record of growing this very rare plant from seed. This is what it looked like originally:

My own Dendrosicyos socotrana on 9/25/11…

I left my newly purchased plant outside in a full-sun position and its leaves promptly began to dry up, probably because it had been kept in a greenhouse at UC Davis and wasn’t used to full sun. Fortunately, after a short while, new leaves began to appear. This is what my Dendrosicyos socotrana looks like now, happily ensconced inside the house:

…and on 12/18/11

New leaves, 12/18/11

In its native Socotra (the only place in the world it is found), Dendrosicyos socotrana grows into a strange-looking but oddly majestic tree:

Photo source: Lifeglobe.net

Photo source: http://yemen.way-nifty.com/blog/2010/12/index.html

▶ Stapelia gigantea

Stapelia gigantea, commonly called “carrion plant” or “toad plant,” is found in southern and eastern Africa and superficially resembles a euphorbia or cactus. They form ever-increasing colonies and in the summer produce very large flowers which release an odor of rotting meat in order to attract pollinators, mostly flies. Stapeliads are very popular with collectors and a great deal of information is available on the web. This is a good place to start if you want to find out more.

My own Stapelia gigantea (left), purchased in November at Poot’s Cactus Nursery

Stapelia gigantea flower. I chose this photo because the hand gives a sense of scale.
Photo source: Wikimedia Commons

   ▶ Euphorbia cylindrifolia

The next five plants are all members of the genus Euphorbia. It’s one of the largest and most diverse genus in the plant kingdom, comprising more than 2,000 species that range from shrubs and trees (many resembling large columnar cacti) to annuals and perennials. The poinsettia is a euphorbia, as are crown of thorns and the European spurges.

The genus Euphorbia also comprises a number of oddities, like Madagascar native Euphorbia cylindrifolia. Its stems resemble octopus tentacles and even its leaves look strange. Eventually, it forms a large underground caudex which can be raised (see 2^nd photo below, taken by my friend Candy “Sweetstuff” at the Huntington Botanical Gardens in Southern California).

My Euphorbia cylindrifolia in a 4-inch container

Euphorbia cylindrifolia at Huntington Botanical Gardens
© Candice Suter. Reproduced with permission.
Click here to visit Candy’s blog.

▶ Euphorbia francoisii

Euphorbia francoisii is another plant endemic to Madagascar. Like so many species with narrow distribution, it is threatened by habitat loss. If you think my small plant isn’t much to look at, this description from the web site of the Cactus & Succulent Society of America may help you visualize its potential:

[T]he leaves and stems are the conspicuous features of these plants. With E. francoisii attractive cream color stems emerge from a geophytic caudex, or from a tangle of fat roots if the plant is a cutting. The branches sprawl gracefully in a random fashion making each plant a unique living sculpture. The uniqueness of each francoisii plant's leaf coloration and branch architecture is what I like most about this species. Every plant is a beautiful ever-changing, singular expression of Nature's wondrous and artistic hand.

My Euphorbia francoisii in a 4-inch container. All you can see right now are leaves.

Mature Euphorbia francoisii
© Tobias Wallek. Photo source: http://i38.photobucket.com/albums/e126/TobiasWallek/plants%20schmid%20forum/Euphorbiafrancoisiia.jpg

  ▶ Euphorbia enopla

The next three euphorbias were cuttings I received from my friend Candy when I visited her last month. I stuck them in pots filled with dry succulent mix, and from what I can tell (there are signs of growth on some of the cuttings), they must have rooted. I’ll wait a few more weeks just to be sure, and then I’ll start giving them small sips of water.

LEFT: Euphorbia enopla
MIDDLE: Euphorbia leucodendron
RIGHT and BACK: Euphorbia flanaganii

Euphorbia enopla is a South African native. It forms colonies of short columnar stems that at first glance look a lot like cacti (no botanical relationship, but succulent euphorbias are often called the “cacti of the Old World”). The spines on Euphorbia enopla are very decorative and less lethal than they look.

Euphorbia enopla
Photo source: Wikimedia Commons

  ▶ Euphorbia flanaganii

Euphorbia flanaganii is one of the medusa-head euphorbias. Its sprawling stems resemble the serpents that ringed the head of Medusa. Check out this interesting article from Dave’s Garden on medusoid euphorbias.

My cuttings have definitely rooted—the brighter green “shoots” on the left are new growth.

New growth on my Euphorbia flanaganii cuttings

Here is a mature specimen of Euphorbia flanaganii at Ruth Bancroft Garden:

© Kelly Kilpatrick, Flora Dora Gardens. Reproduced with permission.
Click here to visit Kelly’s blog.

 ▶ Euphorbia leucodendron

Euphorbia leucodendron is a spineless shrub from Madagascar with cylindrical branches a little thicker than a standard pencil, hence its common name “pencil tree.” In its native habitat it is known to grow to 12 ft. but in cultivation 4-6 ft. is more typical. For most of the year, the branches are bare, but in summer tiny leaves appear on the growing tips (see here).

According to some sources, Euphorbia leucodendron is hardy to 25°F, so I may leave mine outside next winter. By then it will have fully rooted and put on quite a bit of growth.

Larger Euphorbia leucodendron in Candy “Sweetstuff’s” collection.
Click here to see more Google image results.

▶ Euphorbia lactea ‘Rainbow Crest’

The regular form of Euphorbia lactea is an upright shrub or small tree up to 15 ft. in height (check out this impressive specimen). The crested form, sometimes indicated by the Latin word “cristata,” is a natural or environmentally induced mutation that causes the normally straight stems to twist and undulate. The result is often so bizarre that it borders on the ugly. But many succulent collectors are fascinated by such oddities, myself included.

There are many different crested forms of Euphorbia lactea, varying in color and shape. They are considered very difficult to grow on their own roots due to the lack of chlorophyll. For this reason, they are typically grafted onto hardier euphorbias such as Euphorbia neriifolia.

Euphorbia lactea ‘Rainbow Crest’ has become very popular. I bought mine at Lowe’s, but I’ve also seen beautiful specimens at IKEA.

Euphorbia lactea ‘Rainbow Crest,’ grafted on Euphorbia neriifolia

Euphorbia lactea ‘Rainbow Crest’

▶ Discocactus araneispinus

The only cactus I’m overwintering inside is Discocactus araneispinus, a small cactus from Southern Brazil. Considered the easiest member of the genus Discocactus, it’s still not an easy cactus to grow. It wants to be kept at temperatures above 50°F and can rot easily if overwatered. At the same time, it needs some water, otherwise its fine roots will desiccate. Definitely a higher-maintenance plant than what I’m used to!

Discocactus araneispinus

At 2,103 words, this ended up being the longest single post I’ve written to date. No wonder it took me all week to finish it! I get very excited when I discover something new, and I hope some of my enthusiasm has rubbed off on you. Who knows, maybe you’ll end taking a walk on the weird side of the plant kingdom in the new year!