Full text of the article about dwarf camellia I wrote a year ago and mentioned in previous post.
This article was published in American Camellia Yearbook 2011.
Полный текст статьи о карликовых камелиях, которую я написал год назад и про которую я написал в предыдущем посте.
Camellias for dwarfs and elves
American Camellia Yearbook 2011
A big disadvantage of the camellia hobby is the fact that eventually almost every camellia is going to become a large tree. Yes, it is possible to prune camellias severely and even create a camellia bonsai. However such drastic techniques are not only labor intensive – they go against the natural habit of growth for the majority of camellias. Are there any dwarf camellias, suitable for a camellia hobbyist with little available space – let’s say, a balcony in a city? Yes and no. There are several camellias that come close, but their variability is no match for the variability of their large camellia relatives. This situation creates an opportunity for the camellia hybridizers of different ranks, including both professionals and backyard hybridizers.
What is a dwarf camellia? An ideal plant should have small leaves, relatively short internodes, high density of foliage and miniature attractive flowers. In addition, a camellia hobbyist would expect to have cultivars with different habits – willowy for groundcovers, rigid and upright for cypress-like columnar growth and everything in between – drooping, spreading, et cetera. A dwarf camellia should be also slow growing, although some people would prefer to have a fast growing cultivar with fine texture (small leaves and flowers) to quickly create a medium-size plant and then control its size with pruning.
Ideally, a set of dwarf cultivars should have all the flower variations available for the rest of camellias – both in color (white, salmon pink, pink, dark pink, red or bicolor) and in form (single, semidouble, formal double, peony or anemone). Unfortunately, only a fraction of the desired combination exists among dwarf camellias.
Last, but not least, it is very desirable to have dwarf cultivars that are easy to grow. So far, many slow-growing and fine-textured camellia cultivars I have are delicate – they have weaker root system and require careful observation when to water and when to fertilize them. These cultivars are also difficult to propagate through grafting and even more difficult by rooting cuttings.
This article describes only camellia species that belong to the section Paracamellia of the genus Camellia, according to the classifications of Robert Sealy (1958) and Ming Tianlu (2000). (Footnote: There is another classification by Chang Hung Ta (1981) that splits Sealy’s Paracamellia section into two sections (Paracamellia and Oleifera), but many botanists, including Dr. William Ackerman feel that these sections are so close that the split is unwarranted.) This section includes sun tolerant Camellia sasanqua, oil-producing Camellia oleifera and many species that potentially cross-breed with Camellia sasanqua, including C. grijsii, C. microphylla, C. puniceiflora and others. The species from the section Paracamellia have generally smaller leaves than the species from other sections, notably from section Camellia that includes popular species C. japonica and C. reticulata. There are some species from other sections of Camellia genus that have small leaves – notably from section Theopsis, but those species are too botanically distant from C. sasanqua group to cross-breed with them.
There are not so many horticulturalists who observed the inheritance of dwarfness in Camellia. An important observation was made by Dr. William Ackerman from Maryland, when he was working on Camellia cold-hardiness program. When crossing non-dwarf C. oleifera ‘Plain Jane’ with non-dwarf C. sasanqua ‘O’Nishiki’, Dr. Ackerman observed that a quarter of hybrids had genetic dwarfness features – slow growth, smaller leaves and internodes. This classical Mendelian 3:1 ratio suggested to Dr. Ackerman that the dwarfness was in this case regulated by a single recessive gene that was heterozygous in two parents. The same gene was probably acting in well-known Ackerman dwarf hybrids ‘Winter’s Rose’ and ‘Winter’s Red Rider’. However this gene may not explain more extreme cases, like a cultivar ‘Jewel Box’ from Nuccio’s Nurseries in Southern California that has much smaller leaves than Ackerman’s hybrids.
‘Jewel Box’ is the smallest of sasanqua cultivars – its typical leaf is just 30×12 mm as comparing to a more regular leaves of sasanqua cultivar ‘Jean May’ that measures 62×28 mm or a typical Camellia japonica leaf of ‘Kamo Honnami’ that measures 90×60 mm. ‘Jewel Box’ originated in Nuccio’s Nurseries, California. It produces a lot of somewhat wavy single white flowers, sometimes with a pink tint on the border. It appears this cultivar was used to decorate Japanese garden in Huntington Library and Gardens in Sam Marino, California. This garden has the healthiest and best maintained ‘Jewel Box’ planted between rocks along the sidewalk.
‘Jewel Box’ does produce seeds and these seeds sprout, so the cultivar can be used for breeding. However the seedlings are very delicate and easily die when overwatered. The plant’s root system is not very strong, so it is important not to overwater, over-dry or over-fertilize the plant. When grown under sub-optimal condition, this plant frequently shows chrolosis (yellow blotches on leaves) or even have deformed undeveloped leaves. It is difficult to say whether it is a genetic feature, or a result or some virus infection that are frequent among camellia cultivars and result in blotched flowers in pink camellias.
‘Jewel Box’ grows slowly but can be grafted, although it is not the easiest plant to propagate by grafting. Some grafts initially take, but stop growing next year and do not grow beyond stunted stage with a lot of almost opened buds, but no real sprouts. Some other grafts not only take and grow, but develop several large leaves before going back to the size of leaves normal for ‘Jewel Box’. ‘Jewel Box’ may be an interesting subject for a researcher to try different plant hormones – synthetic auxins, gibberellin, etc.
One of the best dwarf sasanqua cultivars is ‘Dwarf Shishi’ (leaf 40×20 mm), a seedling of well-knows cultivar ‘Shishigashira’ of so-called Camellia x hiemalis group of hybrids. (Footnote: C. x hiemalis for a long time was considered to be a species, separate from C. sasanqua, until genetic research proved that C. x hiemalis originated from some ancient hybrid of C. sasanqua with C. japonica). ‘Dwarf Shishi’ was originated by Japanese-American horticulturalist Toichi Domoto (1883-1992) in San Francisco Bay Area. This cultivar has attractive dark pink rose-form double flowers, rigid branches, dense low-growing bush and reasonably strong root system. A scion of ‘Dwarf Shishi’ is very easy to graft on some old overgrown camellia – it quickly produces a very dense sturdy plant. ‘Dwarf Shishi’ is definitely a very promising parent for hybridizing.
There is another cultivar called ‘White Dwarf Shishi’, distributed by Nuccio’s Nurseries. It is not clear whether it is a seedling of ‘Dwarf Shishi’. ‘White Dwarf Shishi’ is a nice plant with double white flowers and straight branches, but its branches are slightly more flexible, habit is more upright and the shape of flowers is different from ‘Dwarf Shishi’. Tom Nuccio hypothesized that this cultivar may be the same as another slow-growing cultivar ‘Kira-shiro-kantsubaki’, but this is certainly not the case – the cultivars of ‘Kira-shiro-kantsubaki’ I got from two different sources (Nuccio’s Nurseries and Camellia Forest Nursery in North Carolina) – are different, especially in flower shape.
Next plant I would like to present is ‘Tanya’ – a well-known cultivar of Japanese origin. The name is not Russian ‘Tanya’, but a Japanese name of a classic Japanese drama. Technically speaking, this cultivar is not a dwarf – it can grow to large size, but its leaves are smaller than leaves of most sasanqua cultivars, and its branches are very flexible, almost willowy, which makes it suitable for groundcovers and even dramatic-looking bonsai-like container plant. ‘Tanya’ produces masses of single pink flowers of a nice tone, and these flowers generate a lot of seeds. I have one seedling of ‘Tanya’ with very small leaves (20 x 12 mm) and numerous seedlings with leaves much below average size. This shows that ‘Tanya’ is a very useful parent plant that can be crossed with double cultivars like ‘Dwarf Shishi’ and others.
There is another unusually-looking cultivar ‘Twinkle Twinkle’ (typical leaf 45×20 mm) from Nuccio’s Nurseries. It is slow growing; it has small leaves and star-shaped little white flowers. This is a cute plant to have, however its root system is weak, which makes the plant quite finicky, and I never got any seeds on it. The shape of the flower is unusual for sasanqua and I would not be surprised if it happens to be an accidental inter-species hybrid.
I already mentioned cultivars ‘Winter’s Rose’ and ‘Winter’s Red Rider’ that originated from Dr. William Ackerman’s cold-hardiness research that started in late 1970s, when Dr. Ackerman discovered that a close sasanqua relative, Camellia oleifera, is more cold-hardy than other Camellia species and can be used to extend the geographical range of camellia growing.
‘Winter’s Rose’ is a cross between C. x hiemalis ‘Otome’ and C. oleifera ‘Plain Jane’ (pollen). It has relatively large leaves and would not qualify to be dwarf based on purely leaf size. However it is very slow growing and has low-growing habit, so I would call it a dwarf with some reservation. ‘Winter’s Rose’ has strong branches, dark leaves and very nice rose-form double pink flowers – flower shape is a strong point of this cultivar. Unfortunately it has weak root system and is sensitive for overwatering or over-fertilizing. I would recommend to graft it on something stronger, like ‘Kanjiro’, but I not sure whether ‘Winter’s Rose’ will keep its dwarfness being grafted on a strong rootstock – a growth habit of a plant is controlled by a complicated equilibrium of plant hormones and roots sometimes influence the shoots, although this influence is not inheritable by its offspring.
‘Winter’s Red Rider’, another Dr. Ackerman’s cross between C. hiemalis ‘Shishigashira’ and C. oleifera ‘Lu Shan Snow’ (pollen), has single pink flowers and smaller leaves than ‘Winter’s Rose’. Unfortunately I was not able to grow it well because two plants I got had very weak root system and grafts were not successful.
One of the strangest sasanqua plants available is ‘Sasanqua Compacta’ – a cultivar from Nuccio’s Nurseries that has normal size leaves and large single white flowers, but abnormally short internodes. It is probably a consequence of some mutation that severely restricts the production of one of plant growth hormones or possibly broke some specific biochemical pathways related to the hormones without affecting other pathways. It would be an interesting experiment to graft ‘Sasanqua Compacta’ on some strong rootstock (like ‘Kanjiro’ and ‘Narumigata’) and see whether the graft starts growing normally when it is supplied by the growth hormones synthesized by its rootstock.
There are a lot of low-growing cultivars from Paradise Plants nursery in Australia, for example ‘Paradise Little Liane’, ‘Paradise Petite’, ‘Paradise Little Liane’ and others; they are claimed to be true miniatures, with small leaves and habit. However these cultivars are not available in the United States, probably because of export or propagation restrictions.
In order to create novelties, some hybridizers cross not just different cultivars of the same species but different species. There are several interesting species with small leaves from Paracamellia section, notably some varieties of Camellia grijsii, Camellia puniceiflora and Camellia microphylla.
Camellia grijsii has both large and small leaf varieties. The most distinctive feature of C. grijsii is its deep and clearly visible leaf veins. A wild form of C. grijsii has wavy single white flower. There is a rare Chinese cultivar Camellia grijsii ‘Zhenzhucha’ that has miniature rose-form double white flowers and small leaves (35-40 x 21-23 mm). It is very difficult to explain why this cultivar is not selling yet in every garden store in California and other Camellia states. The flowers are beautiful and the plant is easy to grow (especially when grafted). It is possible that this cultivar is a recent import from China – at the moment Camellia grijsii ‘Zhenzhucha’ is available in Nuccio’s Nurseries but nowhere else I am aware of. This cultivar produces a lot of seeds and might be a good potential parent.
Camellia puniceiflora is another species that has both large and small leaf varieties. The small leaf (37-40 x 16 mm) variety has small pink flowers with balls of bright yellow stamens. Camellia puniceiflora is easy to propagate using grafting; it produces a lot of seeds and can be used in hybridization. The only downside – it is not really a dwarf itself because it quite quickly grows into a large spreading bush with low density of leaves. Most plants I would call ‘dwarfs’ are dense and slow-growing.
Another non-dwarf plant with small leaves is ‘Starry Pillar’ (typical leaf 32×16 mm). This is a new cultivar from Nuccio’s Nurseries with masses of snow-white single flowers of the shape that suggests this is not a sasanqua, but an interspecies hybrid. Nevertheless ‘Starry Pillar’ is very sun-tolerant, just like true sasanqua cultivars. It also has a vertical habit with quite dense foliage. I never saw ‘Starry Pillar’ making seeds so it is difficult to tell whether it can be used in hybridization.
Another small-leaved cultivar with even more distinctive columnar habit is ‘Slim’N'Trim’, also from Nuccio’s Nurseries. Its leaf sizes vary widely but give it a sunny spot with not so much fertilizer, and it will grow into a dense column with small leaves (40 x 17 mm). ‘Slim’N'Trim’ makes medium-size single pink flowers with narrow petals and sometimes produces seeds.
Finally, there are several non-dwarf cultivars that are worth mentioning because their leaves are smaller than the leaves of average sasanqua and these cultivars possess at least some features useful for hybridization program. ‘Silverado’ from Nuccio’s Nurseries is slow-growing smaller leaf (45 x20 mm) cultivar with single white flowers and very rare silvery color of its leaves. ‘Enishi’ is a classical Japanese slow-growing cultivar with smaller than average sasanqua leaves (40-50 x 17-20 mm), drooping growth habit and rose-shape, almost formal double pink flowers. ‘Rosy Pillar’ is a new sasanqua from Nuccio’s Nursery with columnar habit, single pink flowers, smaller leaves (50 x 20 mm) and good seed production. ‘Shikoku Stars’ is a dense wild variety of Camellia sasanqua with many relatively small plain white flowers.
As we can see, there are very few sasanqua cultivars that can be truly called “Camellias for dwarfs and elves”. A relatively solid candidate for this title is Dwarf Shishi, other good candidates are ‘Jewel Box’ and ‘White Dwarf Shishi’. Rest of candidates can be called ‘dwarfs’ with some reservations – they are either not so dwarf, or not available in the United States, or require more than usual care to stay in shape and healthy. It is likely that a new generation of better dwarf camellias is going to be introduced in the future, and the most promising candidates are waiting both professional and amateur breeders on their seedling benches.
- Ackerman, William L. 2007. Beyond the Camellia Belt. Breeding, Propagating, and Growing Cold-Hardy Camellias. Batavia, Illinois: Ball Publishing.
- Camellia Forest Nursery Catalog. Fall 2007. Chapel Hill, North Carolina.
- Chang Hung Ta and Bruce Bartholomew. 1984. Camellias. Portland, Oregon: Timber Press.
- Gao Jiyin, Clifford R. Parks and Du Yueqiang. 2005. Collected Species of the genus Camellia. An illustrated outline. China.
- Japan Camellia Society. 1999. The Nomenclature of Japanese Camellias and Sasanquas (Nippon Tsubaki . Sasanqua Meikan). English Translation supervised by Thomas J. Savige.
- Macoboy, Stirling and Roger Mann. 1998. The Illustrated Encyclopedia of Camellias. Portland, Oregon: Timber Press.
- Ming Tianlu. 2000. Monograph of the genus Camellia. Yunnan Science and Technology Press, Kunming, P.R. China
- Nuccio’s Nurseries Catalog. 2007-2008. Altadena, California.
- Riess Suzanne B. Toichi Domoto. A Japanese-American nurseryman’s life in California: floriculture and family, 1883-1992. Interviews Conducted by Suzanne B. Riess in 1992. The Bancroft Library, University of California, Berkeley.
- Sealy, Robert J. 1958. A Revision of the Genus Camellia. London: The Royal Horticultural Society.
- Trehane, Jennifer. 2007. Camellias. The Gardener’s Encyclopedia. Portland, Oregon: Timber Press.
Photo albums of the cultivars mentioned in the article
Фотоальбомы культиваров упомянутых в статье