Renanthera imschootiana

Depending on how I do the math, I have been waiting to see these flowers for eight years, or just over twenty five years.  Back in the mid 1990s, when I first started growing orchids, I purchased a seedling of Renanthera imschootiana ‘Saigon’ x self to grow under fluorescent lights in my student apartment in Michigan.  Orchid growers will recognize that it was a poor choice for my growing area; Renanthera species and hybrids require high humidity and very bright light–up to full tropical sun.  After a few years, I came to the same realization and sold the plant to make room for something I had a chance of flowering.

Fast forward to about 2005.  I now lived in North Carolina and had a greenhouse where I could give large orchids much brighter light and higher humidity.  I still loved red flowers, and the very rare R. imschootiana has a certain mystique. I decided to try growing the species again

But I couldn’t find a plant to buy.  This isn’t uncommon if you go searching for one particular orchid.  There are about 28,000 orchid species and hundreds of thousands of registered hybrids, so only a tiny fraction are in commercial production at any time.  Someone flasks a batch of seedlings, and that species is available for sale until they run out.  Then, the species may be virtually unobtainable, unless you know a grower who will give you a division, until someone else produces a new batch of seedlings.

Finally, in 2012, I purchased a seedling of R. imschootiana ‘Newberry’ x ‘Saigon’ from Carter and Holmes Orchids.  That one of the parents of the new seedling was the same as the parent of my old seedling probably speaks to the small gene pool of cultivated plants in the U.S. (Carter and Holmes doesn’t seem to have plants for sale any more, but I see that seedlings are available from Santa Barbara Orchid Estate).

So, about the plant:  R. imschootiana (Assam, northern Indochina, Yunnan) is a relatively small species in terms of leaf-span, although it can grow tall with time.  It is basically a slow-motion vine, taking ten years to grow the distance that a honeysuckle vine could grow in a week, but it eventually grows long enough to need support.  The main stem occasionally branches, and the roots and inflorescences grow from leaf axils at random intervals.  My plant is potted in a 4″ terracotta pot filled with large chunks of scoria (red lava rock).  When it got top heavy, I put the 4″ pot in a 6″ pot, and roots have filled the space between the pots.  The vining stems are supported by several stiff wires.

After a few years in my greenhouse, the plant sprouted a stem that resembled an inflorescence, but instead of flowers it produced a single terminal keiki (plantlet).  The next year, the same thing happened, and the year after.  Many of the Renanthera species and hybrids more common in cultivation are lowland tropicals that grow well in a warm greenhouse, but R. imschootiana is from higher elevation and is noted for tolerating winter temperatures near freezing. Suspecting that the plant was too comfortable with a minimum temperature of 60 F in my greenhouse, I left it outside during the autumn of 2018 until temperatures dropped to near freezing.  I then put the plant on the floor of the greenhouse near the door and reduced watering so that it stayed cool and dry for much of the winter.  Whenever the weather was dry and above freezing, I put it back outside again.  Result: nothing.  Last winter, I just left the plant on a bench in a sunny part of the greenhouse and watered it along with all the other orchids.  Result:  four inflorescences.

So, ~1995-2020 = 25 years.  2012-2020 = 8 years.  Either span is a long time to wait.  I just wish I knew what induced the plant to flower this year.

Six on Saturday #56 (May 23, 2020)

Oxalis articulata

File under things that are counterintuitive:  the Raleigh/Durham, North Carolina area, which I perceive as being fairly sunny year-round,  receives more than twice the annual rainfall of notoriously damp London, England.  Part of the answer to this apparent conundrum is that London has more drizzly days (RDU has 109 days with some precipitation vs London’s 164).  Furthermore, we tend to have tropical-like afternoon thunderstorms during the summer, so many of those 109 rainy days are mostly sunny with thirty or forty minutes of heavy rain around the evening rush hour.

But sometimes we do have prolonged wet periods.  The freeze warning two weeks ago proved to be a false alarm, but this week has also been cooler than normal.  It was the cool of clouds and heavy rain, though, not the chill of dry Canadian air driven south.  Between Monday night and Friday morning, we received 6 inches (~15 cm) of rain.  The garden is looking particularly lush, but some plants are a bit floppy after growing like crazy for a week under heavy cloud cover.

Despite several of this week’s Six on Saturday originating in South America, all are garden plants that grow outside in the ground year round.  Most of these photos were taken last Saturday, before the heavy rain.  They’d look a lot more bedraggled if I photographed them today.

1. Cypella herbertii subsp. brevicristata

Cypella herbertii subsp. brevicristata

Cypella herbertii is a small iris-relative from Argentina and Uruguay.  I have previously written about C. herbertii subsp. herbertii, and everything I wrote about culture applies to this subspecies, too.  Technically, the two subspecies are distinguished by the length of the stigma lobes, but the two forms that I grow also differ in their color:  my T. h. brevicristata has flowers of a clear yellow, while those of my T. h. herbertii are more orange.  This is the first year that my T. h. brevicristata has flowered, so it will be interesting to see if I get a mixture of colors among the volunteer seedlings in future years.

For comparison, here is Cypella herbertii subsp. herbertii

2. Hippeastrum x johnsonii (St. Joseph’s lily)

I featured this hybrid in my very first blog post.  At that time, I was growing it in my greenhouse, but I have since transplanted it to several places in the garden.  The best clump grows in full sun beside the bird bath, in soil that stays damp year round. H. x johnsonii,  a cross of H. reginae (southern Brazil) and H. vittatum (Peru), was the first artificial Hippeastrum hybrid. Its name commemorates Arthur Johnson, an English watchmaker and horticultural enthusiast who first made the cross at the end of the 18th century.  Surprisingly, given the origins of the parent species, H. x johnsonii is reputed to be among the most cold-hardy and vigorous of all Hippeastrum hybrids.

3. Clematis ‘Rooguchi’ (?)

The first flower on a Clematis that I planted last autumn.  I’m not entirely sure that it is correctly labeled.  The flower looks right, but Missouri Botanical Garden’s Plant Finder says that C. ‘Rooguchi’ is a non-vining hybrid lacking the twining petioles that help the vining varieties climb.  My plant definitely has twining petioles and is enthusiastically climbing some deer fencing stapled to the pergola.  Some websites agree with MoBot, while others say ‘Rooguchi’ is a climber like my plant.  Perhaps there are several different clones of the same cross all going under the same cultivar name?

4. Foundation plantings

A two-for-one entry.  Along the south-facing foundation of our house, I planted a row of Rosa ‘Home Run’ and a clump of Phlomis fruticosa (Jerusalem sage) which is slowly spreading to surround the roses.  The Home Run rose is single-flowered (which I like) but lacks fragrance (which I do not).  Most importantly, though, it is very resistant to blights and mildews during hot, humid weather.

P. fruticosa is marginally hardy here, so planting along the south foundation gives it sun in winter and protection from cold north and west winds.  Even so, it doesn’t flower very well and is sometimes damaged by snow and ice sliding off the roof. I do like the foliage, though, and the contrast with the glossy rose leaves.

5. Oxalis tetraphylla ‘Iron Cross’

O. tetraphylla is from central Mexico and is one of the Oxalis species that grow from little corms.  I received it as a freebie in a bulb order five or six years ago and decide to chance growing it in the ground.  So far, it has been well-behaved in the garden, tolerating freezing temperatures and showing no tendency to spread and become a weed like some Oxalis.

6. Oxalis articulata (syn. O. crassipes)

I found this plant growing on our property when we first moved into our newly built house.  O. articulata is a South American species with a long history in cultivation, so I suspect that like the Gladiolus ‘Eno Orange’ it may have been planted by previous owners of the land and survived the intervening years when the property was left fallow.  I have since dug it up and distributed the knobbly little rhizomes to several places in my garden.  O. articulata can apparently become mildly invasive in some climates, but my plant seems to be sterile, at least in the absence of another clone, and shows no inclination to spread on its own.

The Propagator is the host of Six on Saturday.  Head over there to see his Six and find links to the blogs of other participants.

Spring lady’s slippers (Six on Saturday #55, May 9, 2020)

The weather has turned unseasonably cold, to the point that the National Weather Service has issued a freeze warning for most of central North Carolina tonight.  If it does freeze, this will be the latest frost in more than 20 years, a full month after the average last freeze for this area.  Consequently, the tropical plants that I have been moving outside over the past few weeks will need to be moved back into the greenhouse or living room this afternoon, probably to stay there until Wednesday at least.  There’s not much to be done about subtropical plants out in the garden which are already well into their spring growth; hopefully the fresh canopy of deciduous leaves on the trees will provide some protection from radiative cooling.

For this week’s Six on Saturday, I am focusing on a single group of greenhouse plants:  tropical lady’s slipper orchids of genus Paphiopedilum.  A google search will turn up reams of information on cultivating paphs, so I’ll only say that I use a potting mix of Orchiata bark, large perlite, and stalite in roughly equal proportions.  To this mix, which is suitable for a wide range of orchids, I add a small amount of crushed oyster shell to provide calcium for the paphs that grow on limestone.

Although different species and hybrids flower throughout the year, there is a peak of blooming in spring.  Here are six that are flowering now.

1. Paphiopedilum philippinense varieties.

No prize for guessing the home range of this species.  P. philippinense is fairly widespread in the Philippine archipelago and consequently exhibits significant morphological diversity.  The plant on the left is a dwarf specimen that I have been growing since 1997.  Its relatively short petals would probably define it as P. philippinense var. laevigatum, a variety that is relatively uncommon in cultivation.  The taller plant, with its long twisted petals, fits the description of P. philippinense var. roebelenii and is more typical of the specimens that are favored by orchid growers.

2. Paphiopedilum QF Ikaika

This is a new hybrid registered in 2019.  Its parentage is Paphiopedilum (rothschildianum x anitum) x philippinense, and I’m going to rate it a solid meh.  I assume the breeder was going for large size (from P. rothschildianum), dark color (from P. anitum), and twisted petals (from P. philippinense).  Instead, the plant inherited mediocre color, moderate size, petals with hardly any twist, and a small, squat pouch.  I’ll give it a few more years to mature, but if it doesn’t improve, it is destined for an orchid society raffle table.

3. Paphiopedilum venustum

According to Hennessy and Hedge [1], this species from the southeastern foothills of the Himalayas was the first tropical lady’s slipper introduced into cultivation (collected 1816, flowered in England 1819).  It has been popular ever since for its veined pouch and distinctively mottled foliage.  It definitely comes down on the bizarre/grotesque end of the scale, rather than pretty/elegant.  I like it.

4. Paphiopedilum callosum var. sublaeve

A dwarf variety of P callosum that seems to be somewhat intermediate between that species and P. barbatum.  This is a first-bloom seedling that I got as a free bonus in an orchid order about a year ago.

5. Paphiopedilum lowii

Compared to the P. lowii that I blogged about last year, this clone has a darker pouch, more brown pigment in the dorsal sepal, and more horizontal petals.  I particularly like the horizontal stance of the petals–

6. Paphiopedilum appletonianum with deformed flowers

This is the second time this plant has bloomed, and the flowers were deformed last year, too.  I’ll give it one more chance to produce a normal flower before I toss it in the compost bin.

The Propagator is the host of Six on Saturday.  Head over there to see his Six and find links to the blogs of other participants.

Reference:

1. Hennessy, E.F. and Hedge, T.A. (1989) The Slipper Orchids, Acorn Books, Randburg, R.S.A.

Six on Saturday #54 (May 2, 2020)

The last ten days or so have been warm enough at night that I have finally felt confident to start moving tropical plants out to their summer quarters. The hummingbirds also arrived about ten days ago, and I have seen the year’s first aerial dogfights around the feeders.  Horticulturally, we have entered the “great green interlude,” the period after the peak of spring bulb and azalea flowering, but before the blooming of the summer perennials.  Although the first roses are opening, and there are still a smattering of bulbs and orchids flowering, the predominant color in my garden is the green of fresh new leaves.

1. Gladiolus x byzantinus

A welcome splash of bright magenta comes from half a dozen Gladiolus x byzantinus bulbs that I received in a trade with a gardener in Texas last year.  This plant from southern Europe has been considered a synonym of G. communis, but Kew currently has it listed as a natural hybrid, G. dubius x G. italicus.  An old heirloom bulb in southern U.S. gardens, G. x byzantinus starts growing during the winter and blooms in spring, long before the hybrids derived from African species like G. dalenii.

2. Philadelphis inodorus (Appalachian mock orange, scentless mock orange) with unusual flowers

P. inodorus flowers with six petals

P. inodorus flowers typically have four petals, but this year I have a stem covered with six-petaled flowers.  The shrub originated as five or six seedlings that I grew in a single pot, so it is possible that the unusual flowers are produced by one of the seedlings, rather than by a single branch that has sported.  However, the plants are now inextricably tangled together, so the only way I’ll be able to propagate this weirdo (assuming it is stable) will be to root a cutting.

Typical P. inodorus flowers

3. Bletilla striata var. albescens

I purchased this orchid as Bletilla striata var. alba, but the flowers exhibit very faint lavender coloration on the labellum.  Therefore, it would seem to be var. albescens, rather than var. alba which should have pure white flowers.  It does not seem to be as vigorous as the typical colored variety, but I think it has its own delicate charm.

4. Phlox nivalis (trailing phlox, pine phlox)

Moss phlox, P. subulata, is often sold by local nurseries as a native plant, but it is primarily a species of the northeast and midwest.  In North Carolina, P. subulata is found only in a couple of counties in the mountainous west of the state.  The superficially similar Phlox that grows throughout the piedmont is P. nivalis. I grew this one from a small cutting collected in Durham County.

5.  A couple of sages

Above, Salvia officinalis (culinary sage) in our herb garden.  Below, Salvia lyrata (lyreleaf sage), a common spring wildflower/weed.  Unlike S. officinalis, which grows as a semi-woody shrub, S. lyrata has a rosette of soft leaves that look vaguely like a dandelion.  I find S. lyrata particularly difficult to photograph, because its flowers stick out in all directions.

6. New plant bench

Last weekend, I built a wooden bench to house my pachypodiums and some of my tropical bulbs during the summer.  The bench is 7′ long x 4′ wide x 2′ high (2.1 x 1.2 x 0.6 m) and is constructed from pressure-treated pine.  It occupies the space formerly used for growing tomatoes, necessitating a search for a new place to grow that crop, but it should reduce spilled gravel and water damage on our wooden deck.

The Propagator is the host of Six on Saturday.  Head over there to see his Six and find links to the blogs of other participants.