Renanthera imschootiana

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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 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.  Roots and inflorescences grow from the leaf axils at random intervals along the main stem which occasionally branches.  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.

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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 (Assam, northern Indochina, Yunnan) 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.

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Behria tenuiflora: cultural enigma

Behria tenuiflora

Generally, by the time I have had a plant for a couple of years, I am fairly sure of what it needs to grow and bloom successfully.  Either that, or I have killed it and am sure of what was not successful. Behria tenuiflora is currently flowering for the first time in my collection, and not only do I not have any idea what induced it to flower, I’m not really sure what caused it to grow.

B. tenuiflora is a small bulb native to the southern end of the Baja California peninsula.  It was once included in the onion family, Alliaceae, but more recently has been classified in the Themidaceae, a small family of bulbous plants from Mexico and the southern United States [1].  Its closest relative is the Mexican Bessera elegans (see entry 2 of Six on Saturday #8), which is commonly available from the big bulb vendors and seems relatively easy to grow as a potted plant in this climate.  On the basis of my success with Bessera elegans, I leapt at the chance to purchase a seed-grown corm of Behria tenuiflora from Telos Rare Bulbs in 2016.

Based on what I had read about the plant, I expected it to be a summer grower–its habitat supposedly receives most of its rain in the summer monsoon–and its growth in 2016 supported that supposition.  It started growing later than my Bessera plants and went dormant later, but it definitely grew in late summer.  However, it did not bloom that year.

In 2017, it didn’t sprout, and at the end of the summer I unpotted it, expecting to find it dead.  Instead, the corm seemed perfectly healthy, just dormant.  The same thing happened in 2018.  In winter 2018-2019, I tried giving it a few light waterings to see if it wanted to be a winter grower.  No, it didn’t.

This summer, I put it outside yet again.   Surprisingly, a single cylindrical leaf sprouted in July, and it has now rewarded me with its bright, candy-like flowers.  Judging by their shape and color, they are surely pollinated by hummingbirds.

I am not certain what caused it to grow and bloom this year.  My best guess–and this is only a guess–is that the growth is a response to moving it from a terracotta pot to a plastic pot this spring.  Behria tenuiflora comes from an arid environment with irregular rain, so I had assumed that it would grow best in soil that dried rapidly.  But perhaps it is adapted to remain dormant after intermittent showers and to grow only when significant rainfall occurs and the soil will likely remain moist long enough for the plant to complete its growth cycle.  The more constant moisture in a plastic pot might be what it needed in order to break dormancy.

I guess I’ll have to wait and see what happens next year.

Reference

Gándara, E., Sosa, V., and León De La Luz, J. (2009).  Morphological and Molecular evidence in the delimination of Behria and Bessera, two genera of the Milla complex (Themidaceae). Bol. Soc. Bot. Méx. 85: 113-124

 

Six on Saturday #45 (May 18, 2019)

The forecast for today is 91 F (32.8 C), and if we reach that temperature it will be the first time we have broken 90 F this year. May 15 is the average date of the first 90 degree day, so we are right on schedule.

1. Herbertia lahue subsp. lahue

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Herbertia lahue has three subspecies–H. lahue lahue, H. lahue amoena, and H. lahue caerulea–and a really odd distribution pattern. The first two subspecies are native to Argentina and Chile, while H. lahue caerulea (prairie nymph) grows along the gulf coast of the United States. This odd disjunct range is shared by several other bulbs and may indicate very early introduction of South American plants to Spanish colonies in North America.

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The flowers of H. lahue, like those of many irids, are very short lived, and the small stature of the plant makes them easy to overlook. Last year, I found a few seed capsules but didn’t see any flowers. This year, I missed the first flush of flowers, as indicated by the green capsule in the foreground, but I happened to walk past the plant just in time for the second flush.

Similar to its larger relatives Cypella herbertii and Cypella coelestis, H. lahue is remarkably cold hardy for a South American plant. It produces its tiny iris-like leaves in winter and goes dormant in early summer.

2. Penstemon murrayanus (scarlet beardtongue)

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This fantastic Penstemon grows naturally in scattered localities in east Texas, Arkansas, and Louisiana. I like the bizarre perfoliate leaves almost as much as the bright orange-red flowers. It’s not difficult to guess the pollinator–hummingbirds, of course.

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I planted a seedling last May, so this is the first time it has flowered in my garden. Hopefully it will produce seed after self-pollination. Penstemon digitalis (photo 5 of SoS #29) is blooming on the other side to the house, so I suppose hybridization is possible. It’s probably unlikely, though. The white flowers of P. digitalis are pollinated by bees, not hummingbirds.

3. Borago officinalis (borage)

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I don’t usually grow annuals, but I’ll make an exception for borage with its fuzzy buds and beautiful blue flowers. It’s one of the traditional garnishes for a Pimm’s No. 1 Cup…and now I’m getting thirsty.

4. Ocimum kilimandscharicum x O. basilicum (African blue basil)

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I picked this up at the Durham farmer’s market simply because we like to try different types of basil in the kitchen. I had no idea that it was such an interesting plant. African blue basil is a sterile hybrid of culinary basil (O. basilicum) and camphor basil (O. kilimandscharicum), If the second species epithet reminds you of “Kilimanjaro,” you’re not wrong. O. kilimandscharicum is native to east Africa. Unlike the the usual culinary basil varieties, which is easy to grow from seed, African blue basil must be propagated from cuttings. Apparently, it roots easily, flowers almost constantly, and is reliably perennial, though not frost hardy.

My wife thinks the African blue basil smells like regular sweet (Genovese) basil, but I detect a definite camphor fragrance that is presumably inherited from O.  kilimandscharicum.

5. Lonicera sempervirens forma sulphurea ‘John Clayton’

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‘John Clayton’ is, as you can see, a yellow clone of our usually red-flowered native coral honeysuckle (see photo 2 of SoS #26). It was originally planted on this pergola together with red L. sempervirens ‘Major Wheeler’, but the voles ate ‘Major Wheeler.’ Hummingbirds and this gardener agree that red clones of L. sempervirens are better, but ‘John Clayton’ is growing and blooming so vigorously that I haven’t the heart to remove it and start over..

6. Teucrium marum (cat thyme) and Felis catus (moggie)

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Bly the cat and his sister Neem both really enjoy visiting the Teucrium marum that is growing in dry sandy soil beside the gravel path leading to my greenhouse. These pictures also illustrate how we let Bly go out in the garden without endangering the local lizards and birds (and without Bly becoming a snack for the coyotes). He tolerates the harness well, as long as the human trails along behind him rather than trying to lead him.

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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.

Paphiopedilum hirsutissimum

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The Paphiopedilum hirsutissimum buds that were slowly opening last week (see #6) are now fully fledged flowers.  I really like the crisping that has developed along the upper edge of the petals.  It’s a shame that the ends of petals have twisted, making them look narrower, but overall I’m really pleased with this plant.

P. hirsutissimum has a fairly broad range extending from northeastern India to southwestern China (See IOSPE for details).  Like most of the plants in cultivation, this is probably P. hirsutissimum var. esquirolei, which comes from Thailand, Laos, and Vietnam.  This variety is less hairy but has larger flowers and more upright influorescences than typical P. hirsutissimum var. hirsutissimum.

I can’t decide if the staminode looks like a grumpy face sticking out its lower lip…

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…or maybe a screaming face with a bristly crew-cut.

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Paphiopedilum malipoense (and others)

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Paphiopedilum malipoense (jade slipper orchid).  First-bloom seedling in my greenhouse today.

Paphiopedilum malipoense is a slipper orchid from southern China (Yunnan, Guangxi, Guizhou) and northern Vietnam that somehow managed to escape the notice of orchid collectors and botanists until the 1980s–the species was described in 1984.  It isn’t the most exquisitely beautiful slipper orchid, but the green flowers with maroon spotting and tessellation have a certain bizarre charm.  The dark spots on the inside of the inflated pouch show through the thin tissue, making the pouch appear mottled.  Most Paphiopedilum flowers are scentless, but those of P. malipoense have a pleasant raspberry fragrance, a characteristic that seems to be passed on to its first-generation hybrids.

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While the flowers of P. malipoense are more bizarre that beautiful, the leathery foliage is simply gorgeous.

I haven’t been growing P. malipoense for very long, but I have had its primary hybrid, Paphiopedilum Lynleigh Koopowitz (P. malipoense x delenatii) for about fifteen years.  P. Lynleigh Koopowitz grows and blooms well in my greenhouse, as does its other parent, P. delenatii, so I have some hope that P. malipoense will prove equally reliable.

 

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Paphiopedilum Lynleigh Koopowitz

P. Lynleigh Koopowitz combines the best characteristics of both parents.  From P. malipoense, it inherits raspberry fragrance and fine markings on its petals, but P. delenatii genes convert the green/maroon color combination to white/purple.  Some P. delenatii specimens are also fragrant, though to my nose they smell quite different from P. malipoense and P. Lynleigh Koopowitz.

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Paphiopedilum delenatii

The history of P. delenatii in cultivation is a fascinating story.  A few plants were collected in Vietnam during the early 1900s, but the species was believed extinct in the wild soon after it was described in 1924.  For the next seventy years, all of the known P. delenatii were descended from a single plant grown at a nursery in France.  Not surprisingly, genetic diversity was almost nonexistent among the cultivated plants, and they all looked virtually identical.  Then, in the 1990s, the species was rediscovered in southern Vietnam, and large numbers of plants were collected (mostly illegally).  Cultivated P. delenatii now includes white (alba) and very dark (vinicolor) specimens.  My plant, shown above, is typical of the old cultivated type.

P. delenatii is now listed as “Critically Endangered” on the IUCN Red List.  One might hope that artificial propagation has reduced collection pressure on the wild population, but somehow I have my doubts.