SUCCULENT SUNDAY: Euphorbia obesa v symmetrica—the UFO has landed

Chief among the pleasures of succulents are their otherworldly shapes and colors. Euphorbia obesa is a very familiar shape... familiar, that is, in a beach ball or balloon! This oblate spheroid is not a common shape in the world of plants.

This UFO-shaped plant is dioecious (unisexual). I think the plant pictured is male, but I'm not completely sure. On my to-learn list is better positive identification of the sex of euphorbia blooms (called cyathia).

Euphorbia obesa var symmetrica

With any luck, I'll have a breeding pair of these choice succulents from southern Africa. Here's my second plant. Look at the cute second body! This kind of branching is quite unusual in this species:

Euphorbia obesa grows wild in the Graaff-Reinet district in the Eastern Cape. The form pictured here (subspecies symmetrica) is found in the Willowmore district, where it's protected voluntarily by some farmers, partly with the effort of enthusiasts from the Euphorbia Study Group of Warrington, England.

The subspecies symmetrica is distinguished from the base type by a rather technical distinction: it produces multiple peduncles from single flowering eyes. Amateur growers and fans of this plant also know that Euphorbia symmetrica stays compact, rather than elongating and growing tall like the species type, Euphorbia obesa.
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See Also
Euphorbia obesa ssp symmetrica at Cactus-Art.Biz

SUCCULENT SUNDAY: Aloe haworthioides, fuzzy wisps with fragrant flowers

Also posted at SentientMeat.Net

Aloe haworthioides (Baker, Central Madagascar) has been blooming for over a week. It's diminutive at just 3 inches across.

Aloe haworthioides Baker, 3" pot, in full fragrant bloom. Flowers smell sweet, almost like orange blossoms.

Flowers are a big draw in the yard even if you're like me, more of a foliage lover. Flowers are a sign the plant is doing well, of its fitness for... well... sex. Today was New Year's Day and the weather was 80 degrees F and sunny, so the winter flowers were heavy with scent.

Aloe haworthioides startled me with the delicious sweetness of its fragrance. You have to sniff very close, but then it smells gorgeous.

Aloe haworthioides flower closeup

The genus Aloe practically defines the pursuit of defining genus of cactus and succulent culture. You can grow giant tree aloes up to 15 meters in height—Aloe barberae, Aloe pillansii, Aloe dichotoma, just to name 3. I have humble specimens of all three, and I love them.
To Aloe barberae's dragon, Aloe haworthioides is a dragonfly .

Aloe haworthioides, closeup of 3" body

Aloe haworthioides is named for the resemblance to its cousins in genus Haworthia. This resemblance is not coincidence; Aloe and Haworthia are genetically close and they hybridize easily.
Speaking of hybridizing, Aloe haworthioides is often used in aloe breeding. Its beauty and promiscuity are also drawbacks: many plants billed and sold as Aloe haworthioides are actually careless crosses from uncontrolled pollination. Sounds sexy... but be careful out there!

In the wild, it makes its home in the central mountains of Madagascar at an altitude of 1200-1800 m above sea level. Although a slow grower, it forms offsets and can reportedly be propagated by cuttings, i.e. removing these offsets.

Aloe haworthioides is stemless, perennial and herbaceous.

Here are some more technical details, cribbed from Peter Lapshin's site. (Someone—Saturn, Santa, or Satan—needs to bring me the new comprehensive book on the genus, Aloes: The Definitive Guide.)

Each plant body has up to 100 leaves, 3–4 cm long, approximately 6 mm wide, gray-green with white buds, arranged  in a dense rosette diameter of 4-5 cm, leaf margins with harmless white hairs or spines. Flower stems 20-30 cm tall, flowers fragrant, white or pale pink, 6-8 mm in length.

Aloe haworthioides from Peter Lapshin's site, http://www.lapshin.org/succulent/o-al-haw.htm

See Also

Aloe haworthioides at Peter Lapshin's site
Aloe haworthioides at Dave's Garden PlantFiles

SUCCULENT SUNDAY: Argyroderma, pale Martian globes with purple topknot

Also posted at SentientMeat.Net

This Argyroderma startled me the other day. I hadn't noticed the bud forming until it I saw its shocking purple petals fully unfurled and sticking straight up.

Argyroderma grown by Mr Sentient Meat

You'll have to take my word that this flower is a purple of such intensity and depth that I've rarely seen a color to rival it. Cameras have a hard time capturing intense magenta and deep purple; my camera is no exception. In real life the petals are a much darker, deeper purple—rather than the hot magenta in this photo. You almost begin to doubt your own eyesight... as if someone has fiddled with the color knobs of the world.

Argyroderma, same bloom fully open the following day

Argyroderma is native to the quartz fields of the Knersvlakte north of Vanrhynsdorp in southern Namaqualand, in South Africa's Northern Cape. All known species in Argyroderma are from this same region.

Like all its relatives known by the monickers "Split Rock" or "Living Stone", Argyroderma is a mesemb—a member of the ice plant family Aizoaceae, formerly Mesembryanthemaceae. Try saying that 3 times fast. I have yet another geeky confession: sometimes I walk around the house repeating this family name to myself: mess-emm-bree-ann-them-AY-see-ee. If I had to explain myself, I guess I'm practicing so that I don't stumble if I have to say it in public. Try it again yourself: meh-semm-bree-ann-theh-MAY-see-ee.

This particular plant was sold to me as Argyroderma 'Purple'. I'm guessing it's cultivated from Argyroderma delaetii, a solitary species which in Nature can have white, yellow, purple, or occasionally even red flowers—in the same population.

Argyroderma blooming in habitat, photo by Etwin Aslander

See Also

Argyroderma delaetii at CactusArt.Biz 

Court, Doreen. (Third Edition, 2010). Succulent Flora of Southern Africa. Cape Town, South Africa: Struik Publishers. ISBN-10: 1770075879. ISBN-13: 978-1770075870.

SUCCULENT SUNDAY: Haworthia tessellata, waxy windowed whorls

Haworthia tessellata 'Neat' shooting a bloom stalk. Can you see the windows in the leaf tops?

Haworthia tessellata is one of my favorite plants. At least, that's what I tell people. At least one friend has complained that I say that about so many plants that it can't possibly be true.

Haworthia limifolia, a close relative of H tessellata but lacking obvious windows in its leaves. It resembles opaque, molded plastic rather than translucent, carved wax.

The latin name tessellata comes from the tiled pattern in the leaf faces. Attractive, yes, but the bigger truth about these odd, waxy leaf faces is this: they evolved to be natural windows. Many Haworthia have adapted this way. Sunlight enters the plant body through these translucent windows and is converted into energy by many layers of chlorophyll-rich cells. This is especially useful in the arid climates where Haworthia tessellatamakes its living; the primary photosynthesis tissues are not exposed to the drying elements.

Haworthia tessellata 'Fang', a select clone named for the teeth and tubercles on the leaf undersides.

Leaves with window tops are described as fenestrate, from the Latin for window: fenestra.

Haworthia tessellata 'Super Tessellata', a beautiful, select clone

What's more, like many succulents, Haworthia tessellata can photosynthesize using Crassulacean Acid Metabolism (CAM). During CAM photosynthesis, the plant opens its stomata only during the cool of the night. It "inhales" in carbon dioxide and stores it in its thick, succulent tissues (while "exhaling" oxygen). During the heat of the day, the carbon dioxide stored deep in the plant can be used in photosynthesis because sunlight passes through the leaf windows, deep into the center of each leaf.

Haworthia tessellata in habitat. Photo by Jakub at http://haworthia-gasteria.blogspot.com/

See Also
Convergent Evolution in Succulent Desert Plants: Comparing Haworthia and Aloe (Africa) With Agave (America)

SUCCULENT SUNDAY: Echinopsis schieliana, upturned birds' nests waving fancy red frocks

When I bought this Lobivia schieliana (syn Echinopsis schieliana), it had no flowers or buds. I got it for the wonderful spines, which turn the rounded (globose) stems of the plant into little inverted birds' nests. It was a homely beauty, a miniature sculpture of meticulously attached pieces of straw spun into whorls. It was in fact a perfect example of a particular cactus aesthetic: curious, ugly-as-beautiful — the implicit danger of spines, tamed by culture... and in this case, by the plant's tendency to use its defensive spines as horny shield rather than stabbing weapons.

And then... out of nowhere... the blooms. Shocking red, raised above the body of the plant on narrow tubes — the better to be seen by their dancing partners... hummingbirds? Much as I want to write about my other strange cacti — exquisite snowy globes or pineapples with spines like bouquets of grass — I can't ignore these flowers any better than the hummingbirds can.

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PS One of the... I say THE... references on cactus just arrived in the mail and I'm very excited: The Cactus Family (2001) by Edward F. Anderson. He writes,

Echinopsis schieliana (Backeburg) D. R. Hunt 1987

Lobivia schieliana Backeberg 1957, L. backeburgii subsp. schieliana (Backeburg) G. D. Rowley 1982Lobivia quiabayensis Rausch 1968, Echinopsis maximiliana subsp. quiabayensis (Rausch) G. D. Rowley 1982Lobivia leptacantha Rausch 1972

Plants often forming clusters from basal branching. Stems globose to cylindrical, often slender, to 4.5 cm (1.8 in) long and 3.5 cm (1.4 in) in diameter. Ribs about 14. Central spine one, often absent at first, bent downward, light brown, 5–6 mm (0.2 in) long. Radial spines about 14, pectinate to radiating, interlacing, light brown. Flowers bright light red; floral tubes slender. Distribution: Peru and Bolivia.

Lithops spp: stolid prima donnas, down-to-earth yet delicate

Lithops sp, tentatively L marmorata, on 2nd day of bloom.
The largest body here is under 2 inches at its widest.

When you walk down the aisle of a plant show or even a nursery department in a big-box store, certain succulents reach out and knock you over. They barely look like plants. In fact, sometimes it's hard to believe they're even alive. Lithops are tiny but they fall into this drop-dead category.

With a name from the Greek for stone and eye or face, Lithops or "Living Stones" are small plants native to the dry Western Cape region of Southern Africa. They are in the same family (Aizoiaceae) as ice plants, also originally from Southern Africa and spread the world over by human travel and other transport.

Unlike their ice plant cousins, cultivated for centuries and easy to care for, Lithops are widely known only since the 1950s (with the collecting and cataloging work of Desmond and Naureen Cole). Not only did they emerge from obscurity recently — they also have a reputation for being somewhat difficult for amateur cacti and succulents growers. (I have killed quite a few of them, and the Lithops flowers pictured are some of my first.) Lithops are adapted to a dry existence, and if watered too much or at the wrong time they can succumb quickly to that omnipresent nemesis of succulent fanciers: rot.

Lithops care is less of a puzzle once you learn a basic lesson about about their special needs in winter: briefly, don't feed or water them. They are not truly dormant, but they are busy with a small, vital, inner task: growing a new leaf pair in the center of the plant. As the new pair (or pairs) grow, they absorb the nutrients from the previous year's pair. The outer pair shrivels and the inner pair (or pairs) emerges from the seam between the two dying leaves. If you water them during this period, you risk rotting the plant or preventing the outer leaves from being absorbed. Even if the plant survives, this can lead to a misshapen and unnatural look, living blobs instead of neat roundish tiles.

Mid-October, the time of this post, is prime time for Lithops flowers. They like to make hay while the sun still shines.

References

Lithops gallery

Lithops.info 

Cole, Desmond; Cole, Naureen (2005). Lithops—Flowering Stones. Cactus & Co. 368 pages (20.7 × 29.5 cm), 644 col. + 5 b/w photos, 3 col. + 85 b/w drawings, 7 maps, 98 habitat photos. ISBN-10 88-900511-7-5. ISBN-13 978-88-900511-7-3

Hammer, Steven (2010). Lithops: Treasures of the Veld. 2nd Edition. BCCS. Softbound; 156 pages; 238 photos. ISBN-10: 0902099922. ISBN-13: 978-0902099920.

Shimada, Yasuhiko (2001). The Genus Lithops. Dobun Shoin. 240 pages (19 × 26.5 cm), 437 col. photos, 1 b/w map. ISBN-10 4-8103-4066-X.