Friday, November 9, 2018

Hillier's Conifers

Last week's Flora Wonder Blog, The Hillier 96, was a review or critique of the Acer palmatum cultivars listed in The Hillier Manual of Trees and Shrubs (2014). The back cover of the manual claims that the contents are “revised and fully updated,” but I suggest that it can never be fully updated and complete. I know that if my observations ever came to the attention of the authors that-be they would wave them off as a vituperative attack by an unknown American nurseryman who lives to nit-pick and argue.

I never take part in internet forums – usually because they are shallow and dumb – but I like the concept. At its most elevated I imagine a free-flowing exchange of ideas and experiences, perhaps presided over by Aristotle as he ambles down the Lyceum path. Oh well, since ol' Stots knew nothing of Japanese maples he can't add to the discussion, but imagine if he was around today and took an interest in any group of plants – though, besides philosopher, he was primarily a marine biologist, he would suffer no foolish or half-baked claims by Hillier, the RHS, me or anybody else. If anything, my critique need not be feared or waved off, for it is from my simple perspective as a propagator, grower and marketer. Though I can occasionally wax poetic about plants, the bottom-line to nursery survival is to adopt Aristotelean methods.

Chamaecyparis lawsoniana 'Blue Surprise'

Even though I may have Euro detractors I'll continue with my review of the Hillier woody plant encyclopedia and focus on the Conifer section. Surprisingly it is a small part of the manual, curiously located near the end, sandwiched between the Climbers and the Bamboos. Of the 57 pages allocated to conifers, one notices that the majority of the genera and species don't contain any cultivars, and that helps to streamline the section. On the other hand Chamaecyparis lawsoniana contains 116 cultivar listings; egad, more than the 96 for Acer palmatum! Europe in general and Britain in particular appears to love their lawsons, and as long as Phytophthora lateralis doesn't infest their plots gardeners can find all sizes, shapes and colors (er...colours). Even though the native to SW Oregon and NW California, when seed was first sent (1854) to the P. Lawson and Son's Nursery, Edinburgh, the specific name of lawsoniana stuck. It was coined, of course, by a Scottish lawyer and botanist, Andrew Dickson Murray (1812-1878). At the creation of the Oregon Exploration Society, Murray became its secretary, and thus began his interest in western North American Coniferae. It seems odd that a Scottish botanist can claim precedence in the naming of an American native, but it's all hoyle in nomenclature, so no foul. I'll concede the lawsoniana epithet, but thank God the British didn't succeed with commandeering our Sequoia gigantea (Sequoiadendron giganteum) by naming it after their naval hero, the Irishman Arthur Wellesley, The Duke of Wellington. Even Hillier doesn't let the matter completely go – after Sequoiadendron giganteum he refers to “Wellingtonia, giant redwood, Sierra redwood. The “big tree”...” C'mon, stop it and quit whining. You lost!

Chamaecyparis obtusa 'Rigid Dwarf'

Hillier lists 47 cultivars of Chamaecyparis obtusa, less than half of that for C. lawsoniana, yet the former is probably more highly-regarded as a source of sophisticated cultivated variants for the modern garden. The obtusa are “blunt-foliaged” while the lawsoniana present themselves in “sprays,” and I suppose I prefer the sculptural tightness of obtusa over the fan-sprays of lawsoniana. C. obtusa is Japanese and world-known as hinoki, from Japanese hino for “fire” and ki for “wood.” Thus you have “firestick,” which probably originated from its primal use as firewood in Japan. These days the wood of the Japanese cypress is “highly valued for its rich, invigorating citrus aroma that can increase spiritual awareness,” at least according to Young Living Company. It will help welcome guests to your foyer or living room with its clean elegant scent, create a calm meditation or yoga space with its light woodsy fragrance, or best of all, can transform your bathroom into a steamy sauna by diffusing its calming scent. I have been to Japan and I agree with all of the above. The famous Osaka castle was built from hinoki wood and the trees grown in Kiso, used for building shrines, are called go shin boku or “divine trees.”

Chamaecyparis obtusa 'Nana Lutea'

Hinoki is well represented in British horticulture, and the cultivated variants listed in Hillier vary with names in Latin, Japanese and English. For Latin, we have a lot of Nana, such as 'Nana', 'Nana Aurea', 'Nana Densa', 'Nana Gracilis', 'Nana Lutea' etc. Nana refers to “dwarf,” but it is probably of baby-talk origin, and has also been used for “grandmother.” Also in Latin, we have old-time cultivars such as 'Caespitosa', 'Flabelliformis', 'Pygmaea Aurescens', 'Lycopodioides Aurea' etc., with the latter actually coming from Japan, though the name is derived from Greek lykos for “wolf” and podion for “foot.”

Chamaecyparis obtusa 'Chirimen'

Japanese names for cultivars of Chamaecyparis obtusa include 'Chabo yadori', 'Chirimen', 'Tsatsumi' and 'Suriroya hiba', the latter which came to us from Bedgebury spelled 'Siuryuhiba.” Of the above only 'Chirimen' is currently in our production. The Japanese word “chirimen” refers to the silk crepe fabric used in kimonos, but there is also an Acer palmatum cultivar – 'Chirimen nishiki' – that features long narrow lobes with a wrinkly texture. Wrinkly also is Chirimen kabocha (Curcubita moschata), a Japanese squash with a rough textured surface, and Chirimen Hokusai, a cabbage with rumpled leaves. Back to the conifer, the dwarf hinoki, one should understand that the obtusa cultivars are highly unstable and variable. What type of cutting or scionwood is selected can affect the growth rate and shape of the desired offspring. Even then, the obtusas can be individualistic anyway, and explains why “crops” can vary. If propagated by rooted cuttings, 'Chirimen' will usually grow as a dwarf irregular upright, although with age – or any stress – it can “go to seed,” where unsightly tiny bubiles partially develop, then abort and turn brown. If grafted on Thuja occidentalis 'Smaragd', 'Chirimen' is less likely to develop this characteristic, plus will grow a little faster. Normally we prune 'Chirimen' into a dense globe where numerous fingerlings poke upward, but I also have a couple of 5' specimens that have not been sheared and they resemble the sparse branching of a Saguaro cactus.

Chamaecyparis obtusa 'Golden Fairy'

Chamaecyparis obtusa 'Butterball'

Hillier's English-named C. obtusa include 'Golden Sprite', 'Golden Fairy' and 'Rigid Dwarf', all attractive cultivars, but all difficult for the nurseryman to make a profit from. Not making the Hillier cut are the wonderful miniatures 'Green Cushion', 'Butterball' and 'Gemstone', though they have been around for awhile.

Abies koreana 'Ice Breaker'

Abies nordmanniana 'Golden Spreader'

As alluded to earlier, many of Hillier's coniferous species do not come with any cultivars, or at least not known to Hillier. For the “true firs” (Abies) there are no cultivars listed for A. bracteata, A. chensiensis, A. cilicica, A. firma and many other species. The Abies with the most cultivars, not surprisingly, is A. koreana, and that is true for the Buchholz collection as well. Even the relatively new 'Ice breaker' is included, called “A remarkable miniature cultivar with a low squat habit. The white undersides of the upturned leaves give the whole plant a silver-blue appearance.” Keep in mind that all older plants of Abies nordmanniana 'Golden Spreader', that I have seen, grow “squat” at first, then eventually assume a leader. Judging by some of the vigorous apical shoots we've seen on our stock, it is possible that most 'Ice Breaker' will also grow upward. Actually, some of these shoots are harvested and grafted, and I imagine the resultant offspring will display a growth habit somewhere between 'Ice Breaker' and the parent 'Silberlocke', and for these grafts we have used the code name 'Super Breaker', just to keep track of them.

Abies koreana 'Ice Breaker'

A. k. 'Ice Breaker' originated in Germany in 1998 from a “witches' broom” found on A. k. 'Silberlocke' according to Hillier...but I already knew that. In fact I have met a few times with the finder, a Mr. Kohout from eastern Germany. Thankfully, Hillier doesn't acknowledge the cultivar name of 'Kohout's Ice Breaker' as Mr. K. would wish because 'Ice Breaker' is a name clean and sufficient on its own, while thank you Herr K. for your remarkable discovery. A. k. 'Silberlocke' has produced a large number of little curvatures from seed, and one in particular was named 'Silver Show' and supposedly displayed even more of the silvery undersides than its parent...but I could never tell them apart. Also there have been other 'Silberlocke' witch's brooms that have been set apart – Don from Porter Howse Farms in Oregon found one – but none so far has shown the vibrancy of 'Ice Breaker', and indeed the Porter Howse find eventually died on the vine.

Pinus koraiensis 'KG'

Obama inspecting the original Pinus koraiensis 'KG'

Note Hillier's use of the term witches' broom. The gardening public might not know what that means, but most nurserymen and plantsmen do: abnormally congested growth on a portion of a tree. Horticulture is replete with cultivars originating from brooms, some include Juniperus squamata 'Blue Star', Metasequoia glyptostroboides 'Miss Grace' and Pinus koraiensis 'KG' ('Gee Broom'). In each case one broom appeared on its host tree and the nurseryman propagated from that more-dwarf wood. I've never called it a witches' broom – to me witch's broom seems more appropriate. A witch with her broom. Witches is plural of witch, so the Hillier word implies that a coven of witches was required to produce the broom, whereas I think that just one witch was sufficient.

Abies pinsapo 'Horstmann'

Abies pinsapo 'Horstmann'

At the Horstmann Nursery in Schneverdingen, Germany, a witch's broom was discovered on an Abies pinsapo 'Glauca'. According to Hillier it was originally distributed as 'Horstmann's Nana' and in America I first knew it as 'Horstmann's Dwarf'. Now we are to just name it 'Horstmann'. Ok – good. It makes a wonderful conifer for the garden, but not really for a small intimate garden or a rock garden because it can get large. My oldest is about 6' tall by 8' wide at 25 years old. Also it can grow a little wild by producing shoots up to 18” long, as if it's trying to revert back to the parent tree's size. It's an annual task that we prune these completely back to the base. Anyway, that's one of the criteria for judging a witch's broom-originating plant, namely, how likely is the plant to revert?

Cryptomeria japonica 'Sekkan'

Hillier lists a couple dozen cultivars in the Cryptomeria section and it's puzzling why some of the names end in -sugi. 'Bandai-sugi', 'Jindai-sugi', 'Rasen-sugi', 'Sekkan-sugi' and 'Tenzan-sugi' are the culprits. The -sugi is redundant since it is the Japanese word for Cryptomeria. Basically Hillier is naming a cultivar Cryptomeria japonica 'Sekkan' Cryptomeria. No dash-sugi is needed after 'Sekkan'. My experience with 'Sekkan' is that it is a superb, colorful garden plant when young. Hillier calls it a “small tree,” but not in Oregon where mine grew to over 30' tall in about 25 years. At some point the cream-yellow of youth loses its vibrancy and then it looks like a chlorotic green tree. Since it was one of the first conifers ever in my original Display Garden I allowed it to stay when it no longer looked good. Finally I gave the removal edict. My employees looked at each other, thinking the boss has really lost it because the tree was doing no harm. In its stead I planted a C. j. 'Rasen' and now I'm much happier.

Cryptomeria japonica 'Spiralis'

Also in the Display Garden is a Cryptomeria japonica 'Spiralis', and when I went through the Hillier book I was reminded that the common name is “Grannies' Ringlets.” Hillier allows that there are a couple of large specimens in Britain, “But as grown in general cultivation, it forms a small, slow-growing bush of dense, spreading habit.” My specimen is broad, but it has shot upward to over 30' tall. I don't brag about these sizes because I would rather have trees of smaller stature and I generally don't like when garden trees grow into – and ruin – each other. I've never grafted a Cryptomeria onto a Sequoiadendron, or vice versa, but boy the bark and foliage look very similar on the two genera.

Fokienia hodginsii

The Chinese conifer Fokienia is “A genus of a single species [hodginsii], related to Cupressus and Calocedrus and resembling Calocedrus macrolepis in foliage.” I used to grow it – my start coming from the Arnold Arboretum where obviously it was growing indoors. One can root Fokienia but it is probably not hardy enough to be grown outdoors in Oregon. For what it's worth, Rushforth in Conifers claims that it is hardy to USDA zone 7: “It appears to be perfectly hardy, being recorded by the Chinese as tougher than Sequoia sempervirens...” I don't know, my original start croaked the first winter after being planted out, and we didn't get below 10 degrees F that year. Before I risked it out in the garden I cut five scions and grafted them onto Thuja occidentalis 'Smaragd', hoping that the rootstock would give the top a hardiness boost. All grafts took and in short time they grew to about six feet tall. They were floppy and unattractive though, and worst of all was a very unsightly graft union. The two genera hooked together but not well, and if I remember correctly, the Fokienia became two-to-three times larger than its rootstock. I sold one with the caveat that “I don't really know what you're getting.” The customer agreed and planted it out in his southern Oregon garden...where it too died the first winter. After that report I dumped my four remaining trees never to grow it again.

Amentotaxus argotaenia

Another Chinese conifer of dubious hardiness is Amentotaxus argotaenia, an evergreen tree in the Taxaceae family. Hillier says “They are ill-adapted for all but the most sheltered gardens in the British Isles and are best grown under glass.” Well, mine are under poly in my not-much-profit hobby house. To propagate we root from hard-wood cuttings in winter, but I don't have space to keep too many of the USDA zone 8 (10 degrees F) trees around. Amentotaxus is known as the “Catkin yew,” in fact the catkins are known as aments, hence the generic name. The specific name argotaenia refers to the silvery undersides of the yew-like leaves and comes from Latin argentum, and that from Greek argyro(s) meaning “silver.” The seed is covered in a green fleshy aril, which then turns to bright red in autumn and then to purple by winter. The species is threatened due to deforestation and its slow rate of growth, plus rats find the fruits tasty and disrupt distribution.

Cuprocyparis leylandii 'Golconda'

I used to grow x Cupressocyparis leylandii cultivars at the beginning of my career, but today you can buy them cheaply at the box stores where their retail price is less than my wholesale costs. The leylandii is a hybrid between Cupressus macrocarpa and Xanthocyparis (Chamaecyparis) nootkatensis and Hillier claims it is the “fastest-growing conifer in the British Isles.” Though both parents are western North American species, the original hybrid occurred at Leighton Park in Wales in 1888 and was grown by C. J. Leyland, and since the hybrid is usually sterile, it can only be propagated vegetatively, usually by cuttings. Personally I hate the hybrid, but I allow that it can make an effective large hedge, and does so quickly, so it could be useful especially if you don't like your neighbors. As I've said before, I keep old editions of the Hillier Manual of Trees and Shrubs, so I can document when plant names change. Somewhere between the 5th edition (1981) Cupressocyparis (Dallimore) became Cuprocyparis (Farjon) in the 8th edition (2014). But I don't have an explanation for why the name was changed.

Dacrydium cupressinum

Hillier describes Dacrydium cupressinum as a member of the Podocarpaceae family, and it is an evergreen conifer native to New Zealand. The “Rimu”* or “red pine” requires a sheltered location in Britain, but it makes a “charming specimen for a conservatory.” I grew it long ago, my start coming from the Strybing Arboretum in San Francisco, where a marvelous specimen graced the outdoor collection. Hillier sites another botanist when he states, “Considered by the botanist Cheeseman to be 'as beautiful and attractive as any tree in New Zealand.'” Thomas Cheeseman (1846-1923) was born in England, but his family left for Auckland when he was six. He was best known for his publication in 1906 of The Manual of the New Zealand Flora. Anyway, I agree with his assessment of the Dacrydium. Though I kept my stock indoors it eventually grew too large and I sold my oldest tree to a California customer. The Rimu would root by hardwood cuttings in winter, but much effort was required to train one into a “tree” – more often you would have a strongly-staked branch-like specimen. Heater failure one winter ended my Rimu run, but thanks for the memories.

*Rimu is the Maori name for the tree.

Cupressus cashmeriana
Picea breweriana

It is always fun for me to go through the Hillier manual. My 2014 copy is well-worn indeed. Even if I grow a particular tree and know it well, I still am curious about the Hillier take on it. The manual is far from dry, and I love the adjectives used to describe trees, for example: remarkable, handsome, elegant, rare and beautiful, most beautiful, striking, unique, distinct, graceful, neat, etc. Cupressus cashmeriana is “One of the most graceful and beautiful of all conifers.” Picea breweriana is “Perhaps the most beautiful of all spruces...” I like these plant descriptions that come through the heart, not the microscope lens.

I've been to the Hillier Arboretum three times, and I would love to go back for another visit. I fantasize about discovering a tree there and taking a photo of it. Then old Harold Hillier would jump out from behind and explain its story. I would never want to wake from that dream.

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