Six on Saturday #20, February 3, 2018

It’s already Sunday across the Atlantic where the host of “Six on Saturday” lives, but it’s still Saturday evening here.   I guess it isn’t too late to participate.  And regardless of whether it’s Saturday or Sunday where you live, you can still head over to The Propagator’s blog to see his Six and links to those of other participants.

It’s still well below freezing most nights, but there are tentative signs of life in the garden…

1. Cyclamen coum



Cyclamen coum isn’t as vigorous and well adapted to our climate as C. hederifolium, but a couple of tiny plants are hanging on under the pines.  Every year, they bloom in the dead of winter, and every year I almost step on them.

2.  Helleborus niger (Christmas rose)


The foliage of Helleborus niger has been flattened by the snow and cold, but at least it isn’t hiding the flowers on their very short stems.  Some people trim off the old leaves of hellebores just before they bloom.  That would certainly make the flowers of this species more visible, but I worry that removing leaves from a slow-growing evergreen species would be detrimental.

3. Lonicera fragrantissima (Winter honeysuckle)


The flowers of Lonicera fragrantissima certainly aren’t spectacular, but the fragrance is absolutely wonderful.  I planted a row of the shrubs at the top of our driveway, at the northwestern edge of our property, so the prevailing west winds of winter spread the perfume down towards our front door.  I’d be quite proud of myself if it wasn’t completely fortuitous.  The direction of winter breezes was the furthest thing from my mind when I was deciding where to plant them.

L. fragrantissima is frequently found on lists of invasive plants, but luckily I very rarely see any fruit and have never found a volunteer seedling.  All of my plants are a single clone, and I wonder if they are not very self-compatible.

4.  Epidendrum stamfordianum


In my greenhouse, this pretty little central American orchid is blooming for the first time.  It is still a fairly small seedling, so I expect to see longer inflorescence with more flowers in subsequent years.

5. Rauhia decora


This is the first year that my Rauhia decora bulb has produced two leaves instead of just one, so I am cautiously optimistic that it may be approaching blooming size.  If it doesn’t bloom this year, then maybe in 2019.

6.  Pachypodium brevicaule


I can see inflorescences starting on several of the spring-blooming Pachypodiums, but P. brevicaule is always the first to flower.


Rubiaceous Ant Plants (Six on Saturday #17, November 25, 2017)

After a couple of weeks absence, here’s another Six on Saturday.  As with previous posts on Pachypodium and Nepenthes, I’m focusing on a single group of greenhouse plants this week.

Myrmecodia platytyrea (Mossman Gorge form) overflowing a 5-inch pot

The epiphytic myrmecophytes (ant plants) of the coffee family, Rubiaceae, are surely some of the strangest plants that grow anywhere in the world.  Their overall appearance is often grotesque: gray or silver or brown blobs with thick, armored stems and sharp spines derived from modified roots.  They cling to tree trunks or hang upside down below horizontal branches, looking like aliens that have inexplicably settled in an Asian forest.  And to top all of that, their real strangeness is hidden inside.  Soon after a seedling ant plant germinates, the hypocotyl–the stem below the cotyledons–starts to swell into a tuber.  As the plant grows, tissue within the tuber dies in a genetically programmed manner, first forming a hollow space and then expanding into a series of tunnels and chambers.  The tunnels are connected to the outside by entrance holes around the base of the tuber, and the chambers are often aerated by pores.

All of this baroque development is for the benefit of symbiotic ant colonies who set up housekeeping in the artificial nest that the plant has grown.  Both insects and plant benefit from the relationship.  The ants get a secure home, and the plant is fed by the ants.  The ants live in smooth-walled chambers and deposit leftover fragments of insect prey and other waste in chambers with wart-like excrescences on the walls.  As the waste decomposes, the plant absorbs nitrogen through the warts.

Myrmecodia tuberosa cut to reveal interior chambers (a photo from my defunct ant plant website, ca. 1998)


Closeup of chambers.  Arrows indicate two warted chambers.  Smooth chambers can be seen at the center of the slice.

The natural range of the rubiaceous ant plants extends from Thailand to Australia and east as far as Fiji, but the greatest diversity is found on New Guinea.  In the mid-1990s, when I first became interested in ant plants, only about five species were in cultivation, and they were very hard to find.  With some effort (i.e. obsessive searching), I managed to connect with a few other like-minded growers via email and traded seed and seedlings with the curators of several botanical gardens.  These days, the plants are (somewhat) easier to obtain, and a wider range of genera and species are in cultivation thanks to the efforts of a handful of hobbyists and nursery owners from around the world.  Several nurseries in Europe and the U.S.A. sell seedlings, and plants are occasionally available on eBay.

So without further ado, here are six (on Saturday) ant plant species:

1.  Myrmecodia platytyrea (Mossman Gorge form)

The plant shown at the top of this post is a very vigorous Myrmecodia descended from material originally collected in northern Queensland.  Like most of the rubiaceous ant plants in cultivation, M. platytyrea has flowers that self-pollinate, so seedlings remain true to type over multiple generations.  The Mossman Gorge form of M. platytyrea produces long, sharp spines and very vigorous roots that often invade the pots of its neighbors.  Its leaves are narrower and more succulent than other cultivated M. platytyrea descended from plants collected in New Guinea.


The shield-like leaf bases on the stems of M. platytyrea are called clypeoli.  The spines bordering the clypeoli hide alveoli, pits in which the small white flowers develop and from which the orange fruit protrudes when ripe.

2.  Myrmecodia sp. “Pink Fruit”


This species has very strong sharp spines and pink fruit.  It is commonly cultivated by ant plant enthusiasts, but its origins are obscure.  Possibly, it is M. tuberosa ‘Papuana’ which grows in New Guinea and northern Australia.

3Myrmecodia tuberosa



This is the most variable and widespread Myrmecodia species, with a range extending from Malaysia to Australia.  The form shown here does not have strongly developed clypeoli, so you can easily see the elongated alveoli filled with papery bracts.

4.  Myrmephytum beccarii


Myrmephytum is a genus of five species found in the Philippines, Sulawesi, and western New Guinea.  M. beccarii is from the Philippines, and was introduced into cultivation in the U.S. around 2006.

5. Hydnophytum moseleyanum


H. moseleyanum is a lowland species from New Guinea and Australia.  Hydnophytum species usually lack spines and have many elongated branches without clypeoli and alveoli.  Their chambers are less complex than those of Myrmecodia.  Note the large entrance hole on the side of this tuber.  Above and left of the entrance hole, a patch of papery dead tissue is peeling away to reveal a new hole.

6.  Hydnophytum formicarum

A very variable and widespread lowland species from Thailand, Malaysia, and Indonesia.  Several different forms varying in size and color are in cultivation.

Hydnophytum formicarum.  A large form from Thailand with entrance holes generally restricted to the underside of the tuber.  The tuber is partially obscured by moss growing up its sides and is larger than it appears.  This plant is twenty-one years old and was the first ant plant I grew from seed.
Hydnophytum cf. formicarum. A plant distinguished by its very broad leaves and smaller tuber with proportionally very large entrance holes.
Hydnophytum cf. formicarum from Belum rainforest, peninsular Malaysia.  This is a dwarf form with brown, flattened tuber and tiny leaves barely as long as those of the Thai form are wide.  Notice the the small entrance hole on the right and pores on the lumpy region at left.

So, that’s six rubiaceous myrmecophytes.  For more Six on Saturday that is perhaps a little less botanically grotesque, head over to The Propagator.

Six on Saturday #3: Pachypodium

Pachypodium horombense

I thought for today’s Six on Saturday I’d stick with a single theme.  I haven’t photographed many plants from the greenhouse lately, so here are six specimens from my little collection of pachypodiums.

I started growing pachypodiums on the windowsill of my student apartment, long before I had any outside space to garden, and some of the plants have been with me for more than twenty years.  These days, they spend the winter in the greenhouse and sit on shelves on our deck during the summer.  My wife keeps making noises about wanting to reclaim the deck for human activities, so at some point I suppose I need to build some benches in a sunny spot (that isn’t already a flower bed) and move the pachypodiums (and minibog pots, and citrus trees) there.

Cactus and succulent growers, in common with bonsai growers, value plants that give the appearance of great age and have the form of wild plants.  With some plants (e.g. semi-succulent trees such as Boswellia and Bursera) it is very difficult to replicate the effects of decades of wind, sun, and drought, so unfortunately there is still a market in wild-collected plants.  Pachypodiums, fortunately, are fairly simple to grow from seed, and even small seedlings are very charismatic.  If grown hard, they will produce a reasonable facsimile of a wild specimen in 5-10 years.

“Hard” in this context means growing the plants in bright light, as close to full sun as you can manage, in small pots with restricted fertilizer.  It is very important to keep the plants in consistently bright light when in growth.  Once the shrubby forms etiolate, it’s all over.  The signs of less-than-ideal-light levels will be visible for decades.

Some of my plants have, perhaps, been grown too hard.  The reponsibilities of family, job, home ownership, and a growing outdoor garden have resulted in some neglect of the pachypodiums.  Some of these plants are years overdue for repotting and are starting to show it.  Maybe this blog posting will inspire me to take care of them better.

So, without further ado…

1.  Pachypodium horombense

As seen at the top of this page, P. horombense is a shrubby species with stout spines that comes from southern Madagascar.  Relatively large, bright yellow flowers with an inflated corolla tube are produced on a long inflorescence in spring.  I purchased this plant as a small seedling in 1999.

2.  Pachypodium bicolor

Pachypodium bicolor

Another shrubby species, this one from central Madagascar, that has yellow flowers with a white throat.  I photographed the flowers for my very first blog posting.  This plant was also purchased as a small seedling in 1999.

3.  Pachypodium brevicaule

Pachypodium brevicaule

I purchased this plant as a pea-sized seedling in 1996.  My second-largest plant is seventeen years old and about half its size.  Offspring of the two old plants are ten years old and various sizes.

P. brevicaule is basically a shrubby species with the branches telescoped down until they form rosettes of leaves.  The inflorescence is also shortened, and the bright yellow flowers are produced more erratically than in the other Madagascan species. In old specimens, the branches form small bumps, giving the plant a lumpy appearance, and when leafless it resembles a chunk of quartz rock.

P. brevicaule grows slowly and a cursory scan of google images will, sadly, show many large specimens that were certainly dug from the wild.  Ironically, this is one of the easiest to grow from seed into a “wild-looking” specimen, although you do need patience.  The compact form is under very strong genetic control, so it is less likely to etiolate in less than perfect light.

Since it is hard to see much of this plant when it has leaves, I’ll cheat and show you another photo taken in 2013 when it was a bit smaller.  Consider this Photo 3b:

Pachypodium brevicaule flowering

4.  Pachypodium (eburneum x bicolor).

Pachypodium eburneum x Pachypodium bicolor

This is my own hybrid, a ten-year old plant grown from seed.  The pollen parent was the P. bicolor shown above.  The morphology of the plant is strongly influenced by P. eburneum, but the flowers have the white throat of P. bicolor.

5.  Pachypodium inopinatum

Pachypodium inopinatum

A white flowered species from north central Madagascar.  I purchased this plant as a one or two-year old seedling in 1999.  In wild Pachypodium specimens, the old spines often erode away, leaving the swollen stem smooth. The same process is occurring in this cultivated plant.

6. Pachypodium ambongense

Pachypodium ambongense

In form, this species is intermediate between the shrubby, generally yellow flowered species and the tree-like, generally white-flowered species.  It is from northern Madagascar and has white, narrowly tubular flowers in autumn and winter.  Purchased as a small seedling in 1998.

Second #6.  Pachypodium saundersii

Pachypodium saundersii

I know this is Six on Saturday, but I can’t resist.  This was my first Pachypodium, grown from seed that I planted in September, 1996.  P. saundersii is from South Africa and has white flowers, flushed with purple pigment, in the autumn.  This big guy is starting to look a little sad.  Needs repotting and some fertilizer, I think.

There are more pachypodiums that I want to show you.  Maybe another Six on Saturday?