Rhododendron viriosum hybrids

flowers of Rhododendron 'Festive Bells'
Rhododendron ‘Festive Bells’

Rhododendron ‘Festive Bells’ is currently flowering in my shade house, so this seems like a good time for a quick post on Rhododendron viriosum hybrids.

R. viriosum is a vireya, a tropical rhododendron, and is one of only two Rhododendron species native to Australia. It has red, bell shaped flowers and is noted for its phenotypic dominance and the vigor that it imparts to hybrids. Hybrids with R. viriosum as a parent almost invariably have bell shaped flowers in some shade of red, and they are usually strong growers. Appropriately, the species name virosum is derived from the same root as the English word “virile”. The species is difficult to locate in the United States, but I am currently growing two first-generation hybrids and have previously grown a third.

Rhododendron ‘Festive Bells’, shown above, is my favorite of the three. My plant, purchased a year ago, is currently blooming for the first time, and the flowers are absolutely amazing. They are some of the best flowers that I have ever seen on a rhododendron, and perhaps on any plant. The color is a pure, intense fire engine red and the flowers have an incredible waxy texture that makes them look as though they are made of plastic. Like many vireyas, R. ‘Festive Bells’ is somewhat lanky with long internodes, but flowers are nicely in-proportion with the plant size. R. ‘Festive Bells’ has R. viriosum as the seed parent, but the pollen parent is unknown.

Flowers of Bovees V97
Rhododendron viriosum x christianae (Bovees V97)

Bovees V97 is an unregistered clone of R. viriosum x R. christianae bred by E. White Smith, former owner the Bovees Nursery in Portland, Oregon. Bovees was for many years the preeminent source of vireya plants in the United States. It closed a few years ago, so I was happy to find this hybrid still offered for sale by Pacific Island Nursery in Hawaii. Genes from R. christianae have imparted orange tones and a more horizontal stance to the flowers, but the plant still has the vigor expected of an R. viriosum hybrid.

flowers of Rhododendron 'Little Maria'
Rhododendron ‘Little Maria’

Rhododendron ‘Little Maria’ was a beautiful little plant that grew in my collection for about five years. The cross is R. viriosum x (viriosum x gracilentum). R. gracilentum is a miniature, cool-growing species from the mountains of New Guinea at altitudes of 2000-2745 m above sea level [1]. Despite the double dose of R. viriosum in the ancestry of R. ‘Little Maria’, R. gracilentum is dominant for plant size. A large specimen of ‘Little Maria’ can fit in a 4″ pot, and both leaves and flowers are about half the size of those of R. ‘Festive Bells’ or V97. Unfortunately, R. gracilentum also seems to be dominant for heat tolerance (or lack thereof). Plants purchased from Bovees died very quickly, but I had better luck with cuttings that I rooted in North Carolina. Anecdotally, I have noticed similar results with other vireyas. When vireya plants in my collection die, it often seems to be because the root system has failed catastrophically in the heat. For some reason, roots that have grown in North Carolina seem tougher–perhaps they have different fungal symbiotes or are better adapted to my potting mix.

Eventually, all of my Rhododendron ‘Little Maria’ cuttings died in the summer heat, and I have been unable to replace them. I am hopeful that V97 will do better in our climate, because R. christianae is from more moderate altitudes of 600-1525 m [1]. Since the other parent of ‘Festive Bells’ is unknown, I will just have to hope for the best, but I have already rooted a cutting as insurance.

Reference

1. Argent, G. (2015) Rhododendrons of subgenus Vireya, 2nd edition. Royal Botanic Garden, Edinburgh.

Six on Saturday #70 (April 23, 2022)

Now that spring is well under way, it is a little easier to find interesting pictures for a Six on Saturday post. Here are five from the outdoor garden and one from the greenhouse.

1. Trillium grandiflorum (great white trillium)

photo of Trillium grandiflorum

Trilliums are, notoriously, very slow to grow from seed or from rhizome divisions. It seems that someone must have mastered the procedure on a commercial scale, though, because mass produced rhizomes have started showing up in garden centers beside the spring bulbs. The packages come from the Netherlands, which probably precludes the possibility that they are wild-collected. I have tried boxes from Durham Garden Center and Costco which both claimed to contain Trillium grandiflorum (white) and Trillium erectum (red). The packages from Costco actually contained Trillium luteum and a red-flowered sessile species, but the box from Durham Garden Center seems to be correct.

2. Trillum luteum (yellow trillium)

photo of Trillium luteum

I planted this species in 2010 or 2011 and featured it once before in 2018. In rich soil, it would probably be a large clump by now. In very poor dry soil under pine and oak trees, it only has two stems, but they return faithfully every spring. Since it spends much of the year hidden under ground, I have left a small eastern red cedar seedling to help mark its location.

3. Clematis ochroleuca (curlyheads)

photo of Clematis ochroleuca

I could have sworn that I had already shown this native plant, but I can’t find it in a search of the blog. In any case, C. ochroleuca, is somewhat unusual for a Clematis, growing as a clump of short, upright stems rather than as a vine. The small flowers and fuzzy stems have a certain understated elegance, but it is the seeds, which look like heads of curly golden hair, that are the main reason for giving it space in the perennial border. I’ll have to remember to photograph them later this year.

4. Taraxacum pseudoroseum (pink dandelion)

photo of Taraxacum pseudoroseum

I wanted to grow some dandelions intentionally for chicken treats and occasional salad greens , and I thought that this would be more interesting than the standard yellow flowers that pop up in the lawn. So far, the pink color has been very faint, most noticeable when the flower first opens, but I think the overall effect is very attractive. My wife has included a second species, Taraxacum albidum (Japanese white dandelion) in her seed trays this year, and the first two seedlings were visible this morning.

5. Tulipa linifolia

photo of Tulipa linifolia flower

After several years of testing, I am convinced that a number of the smaller tulip species (Tulipa clusiana, T. whittalii, T. sylvestris, and T. linifolia) grow well in our climate. Unfortunately, rodents love to eat the bulbs, and this year about 90% of my tulips vanished. There was a concomitant increase in the number of pine vole tunnels in the flowerbeds, so I am fairly sure who the culprits are. The survivors, like this T. linifolia, are the ones that were planted in soil amended with permatill or in naturally gravelly soil.

6. Columnea schiedeana

photo of Columnea schiedeana flowers

Columnea schiedeana is an epiphytic gesneriad from Mexico. The hummingbird-pollinated flowers have fairly standard shape for a Columnea, but the color is amazing–each one looks hand-painted.

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

First bloom: Eucrosia eucrosioides

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Eucrosia eucrosioides, first flowers from a bulb purchased in 2016

Just as the Cyrtanthus falcatus inflorescence was fading, I noticed that another tropical bulb was in bud for the first time. Eucrosia eucrosiodes is from arid scrubland in southwestern Ecuador and northern Peru. In its flower structure, leaf shape, and cultural requirements, it resembles its close relatives Eucrosia mirabilis and Eucrosia aurantiaca. I grow E. eucrosioides almost exactly the same way I grow those two species, with plenty of heat, water, and sun in summer and a warm dry rest in winter. Like its relatives, E. eucrosioides is strongly hysteranthous–that is, it flowers at the end of the dry dormant period, before new leaves are produced, so a naked inflorescence sprouts from what appears to be an empty pot.

Like E. mirabilis and E. aurantiaca bulbs, E. eucrosioides bulbs show no inclination to offset and must be grown from seed. E. mirabilis can be self-pollinated and produces viable seed, but E. aurantiaca seems to be self-sterile. I’m not sure yet whether E. eucrosioides will be self-fertile, but I have a second clone which has not yet flowered. If I can manage to flower both at the same time, perhaps an outcross will be a possibility sometime in the future.

The genus name of this plant makes perfect sense–Eucrosia means “beautiful fringe”, referring to the elongated stamens–but its species name is a little odd. In botanical Latin, the suffix -oides means “like” or “resembling”, so Eucrosia eucrosioides would be “the Eucrosia that resembles a Eucrosia.”

Eucrosia_eucrosioides2

First bloom: Cyrtanthus falcatus

Cyrtanthus-falcatus1
Unusually pale Cyrtanthus falcatus flowers. The “shepherd’s crook” curve at the top of the inflorescence is a distinctive characteristic of this species.

Cyrtanthus falcatus is a large amaryllid from South Africa. Its species name comes from its sickle-shaped leaves which recall the falcata sword favored by ancient Iberian tribes (think of a Gurkha kukri for a modern equivalent). Its flowers and its bulbs, which grow exposed at the surface, are roughly the same size and shape as those of C. obliquus which I have previously discussed, but I have found it much more difficult to flower than the latter species. After first flowering in 2017, my C. obliquus has continued to bloom every year, but this is the first inflorescence on a mature C. falcatus that I have been growing since 2014. The difference is probably due to C. obliquus being better suited to spending the winter in my heated greenhouse. C. obliquus is a lowland species, found from sea level to 1300 m in the eastern Cape northwards to KwaZulu-Natal. C. falcatus, while it also grows in KwaZulu-Natal, is a highland species found from 1100-1900 m on the Drakensberg escarpment [1]. Consequently, C. falcatus probably requires colder winter temperatures to initiate spring flowering.

Cyrtanthus-falcatus2
Sunbird’s-eye view of the flowers

I grow both plants outside in full sun during the summer and move them to the greenhouse in autumn. I bring the C. obliquus into the greenhouse before nights drop much below 50 F (10 C), but I leave the C. falcatus outside until the first frost is forecast. Although C. obliquus spends the winter on a greenhouse bench among tropical plants, I put the pot of C. falcatus on the floor where it is cooler. Usually, the plant has already dropped all its leaves and is dormant before it goes into the greenhouse. The pot remains dry all winter, and I start to water again only when I see new leaves sprouting, usually in March. The pot goes back outside in April, as soon as possible after the last frost. This winter, I put the pot right beside the greenhouse door to give it the coolest (but still above freezing) temperatures possible. That may be what finally induced flowering.

The large tubular flowers and sturdy inflorescence of C. falcatus probably indicate that it, like C. obliquus, is pollinated by sunbirds. Since birds generally prefer flowers in shades of orange and red, I was surprised by the green flowers of my plant. Most photos online do show orange flowers, but the species is apparently quite variable and green flowers are within the range of color reported for the species [1]. Since I already have C. obliquus and several smaller Cyrtanthus species that are orange, I am quite pleased with the unusual color of my C. falcatus.

Reference

  1. Duncan, G., Jeppe, B., and Voight, L. (2016)  The Amaryllidaceae of Southern Africa, Umdaus Press, Pretoria, South Africa.
Cyrtanthus-falcatus_whole plant
Whole plant, showing the above-ground bulbs

The Genus Encyclia–Part 5, hybrids

(Start at The Genus Encyclia–Part 1)

To close out this series on Encyclia orchids, we should probably consider hybrids. Broadly speaking, Encylia species are genetically compatible with each other and with other members of the subtribe Laeliinae. Natural hybrids among Encyclia species do occur, particularly in the Caribbean, but as far as I am aware, intergeneric hybrids are purely a phenomenon of cultivation. When crossed together, Encyclia species produce hybrids that are, as one might expect, not dissimilar to the original species. The hybridization merely extends the color variation of the genus somewhat and, perhaps, introduces some hybrid vigor. When crossed to other genera in the Laeliinae, Encyclia contributes genes for compact growth and long inflorescences with multiple, relatively small flowers. Other genera such as Cattleya or Guarianthe extend the color palette and shorten the inflorescence. The intergeneric hybrids are often excellent plants for growing on sunny windowsills.

Encyclia Gail Nakagaki

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E. Gail Nakagaki

E_Gali-Nakagaki2

Encyclia Gail Nakagaki (see also photo 4 here) is an excellent example of a primary hybrid between two species. The form and color of the flower is intermediate between its parents, E. alata and E. cordigera, while the fragrance is strongly influenced by E. cordigera.

Encyclia (chiapasensis x bracteata)

E_chiapasensis_x_bracteata
E. (chiapasensis x bracteata)

This interesting miniature hybrid was bred by North Carolina orchid grower John Martin, and he very generously gave me a seedling about ten years ago. E. bracteata is a miniature species, while E. chiapasensis is noted for its successive blooming pattern. The hybrid is a dwarf, suited to growing on a windowsill or under lights, which has inherited the successive blooming habit from its larger parent. Instead of producing all of its flowers at one time, each inflorescence produces a few flowers at a time over a long period. A mature plant can be in flower for much of the year, a feature which is obviously appealing to windowsill orchid growers. I am surprised that E. chiapasensis has not been used more by commercial orchid breeders.

Catyclia Cinnamatica

Catyclia_Cinnamatica
Catyl. Cinnamatica

This hybrid of Encyclia incumbens crossed with Cattleya (formerly Laelia) cinnabarina is a good example of what happens when the non-Encyclia parent is one of the brightly colored, small-flowered Cattleya species in subgenus parviflorae. The plant resembles an Encyclia with elongated pseudobulbs, but the burnt-orange color is not in the natural palette of Encyclia. Because the other parent is one of the lithophytic species formerly called rupiculous laelias, this hybrid wants bright light and excellent drainage.

Enanthleya Middleburg ‘MAJ’ AM/AOS

Enanthleya_Middleburg-MAJ
Eny. Middleburg ‘MAJ’ AM/AOS

Enanthlaya is an artificial genus generated by hybridizing Encyclia, Cattleya, and Guarianthe plants. Enanthleya Middleburg is (Cattleya guttata x Guarianthe bowringiana) x Encyclia phoenicea, and this awarded plant was good enough quality to mericlone and mass market. The beautiful purple color and heavy waxy texture come from both sides of the cross, but the chocolate fragrance is all E. phoenicea.

Enanthleya Joseph Romans x Encyclia cordigera

Enanthleya_unregistered
Eny. Joseph Romans x E. cordigera

This cross was less successful than the previous. While E. phonicea produced nicely proportioned flowers in Eny. Middleburg, the larger lip of E. cordigera has produced ungainly flowers which are crowded together on the short inflorescence influenced by the Enanthleya parent. Perhaps that’s why the cross has not been registered.

Enanthleya Bob Gasko

Enanthleya_Bob-Gasko
Eny. Bob Gasko

Not every Enanthleya is purple. The bright orange color of Eny. Bob Gasko comes from rupiculous laelias and Guarianthe aurantiaca. The cross is (Encyclia incumbens x Guarianthe aurantiaca) x (Cattleya neokautskyi x Cattleya harpophylla), so the genetic influence of Encyclia is somewhat attenuated compared to Eny. Middleburg or Eny. Joseph Romans x E. cordigera. Nevertheless, Encyclia is still clearly visible in the compact growth habit and long, beautiful inflorescence. Unfortunately, this hybrid does not have any fragrance that I can detect.

So, that wraps up my brief survey of Encyclia orchids and their cultivation. Hopefully it has given you some idea of why Encyclia is my favorite orchid genus and, perhaps, whetted your appetite for growing one (or a few, or a greenhouse full).