Trees and Shrubs Part 3: The Hillier Manual of Trees and Shrubs, 9th Edition

When I describe the Buchholz Nursery product line I like to say that we grow three groups of plants: 1) conifers, 2) maples and 3) everything else. Part 1 of my review of The Hillier Manual of Trees and Shrubs 9^th edition covered the conifers, or some conifers, and Part 2 dealt with Acer species. Today's Part 3 will discuss the everything else group, and I'll exclude the Climber and Bamboo sections because I don't know anything about them.

Aesculus hippocastanum 'Wisselink'

Aesculus hippocastanum 'Wisselink'

It's pointless to squabble about what constitutes a “tree” as opposed to a “shrub,” but Aesculus hippocastanum is definitely a TREE and Hillier rates the “Horse chestnut” as “Possibly the most beautiful of large, flowering trees hardy in the British Isles.” I thought the earlier Hillier editions were remiss to not include A.h. 'Wisselink', but the 9^th (2019) finally lists it, and it is described as “A medium-sized tree with distinctive white leaves with lime-green veins.” If I would have discovered it I probably would have given it some “ghost” name, but it was found by William Wisselink of Holland, and it would be a great treat to see the original tree. A nice specimen is growing at Sebright Gardens, just a ninety minute drive south from here, and since they are a retail operation the public is able to visit. While Sebright calls itself a “garden,” make no mistake: they are a full-fledged arboretum, an eclectic collection that is one of the most fun plant destinations in America. The foliage on Sebright's horse looks a little tired now, at the end of a hot summer, but it's remarkable that it is growing in full sun with no burn.

Poncirus trifoliata 'Flying Dragon'

Poncirus trifoliata 'Flying Dragon'

Poncirus trifoliata 'Flying Dragon'

Poncirus trifoliata 'Snow Dragon'

I have had a Poncirus trifoliata 'Flying Dragon', the “Japanese bitter orange,” for almost 30 years. If you look up Poncirus trifoliata in the Hillier 9^th you won't find it and instead you are referred to Citrus trifoliata. No cultivar is mentioned but 'Flying Dragon' has been long in the trade and noteworthy for its more dense, compact form. My first plant was sold at 6' tall by 4' wide, and I imagine it could be double that size if I would have kept it. The Hillier description of the straight species (in the Rutaceae family) is positive, mentioning “Beautiful in spring when carrying its white, sweetly scented flowers...from northern China, introduced 1850.” Considering its place of origin I've never understood why it is referred to as the “Japanese bitter orange,” unless the Japanese make greater use of it than the Chinese. I suppose a palatable marmalade could be made from its skin; but of course I once sampled the flesh – I felt a duty to do so – but spat it out instantly. With the stems' prodigious thorns I think 'Flying Dragon' would make an excellent hedge to keep the neighbor's brats out. Two additional cultivars that we propagate are 'Tiny Dragon', a miniscule dwarf, and 'Snow Dragon' which has variegated leaves and stems.

Parrotia persica

Parrotia persica

Hamamelis intermedia 'Arnold Promise'

Hamamelis intermedia 'Arnold Promise'

Parrotia persica is the “Persian ironwood,” a deciduous bush-tree in the Hamamelidaceae family native to northern and northwestern Iran, and endemic to the Alborz (or Elburz) Mountains. The cut branches can be made to intertwine and are used as livestock fencing. It was introduced to cultivation in 1840 and was named for the German naturalist Friedrich Parrot, a lover of Saltine crackers. Hillier considers it “One of the finest small trees for autumn colour...” and also mentions that the bark and older branches flake delightfully. Thirty years ago I grafted five or six Hamamelis scions into the top of a Parrotia and they made fairly smooth graft unions, so I now have a huge 'Arnold Promise' flowering in late winter, but also a tree that displays year-round appeal of the trunk...and, with far less suckering than by using the traditional Hamamelis rootstock.

Parrotia persica 'Persian Spire'

Parrotia persica 'Persian Spire'

Parrotia persica 'Persian Spire'

The Hillier 8^th listed five cultivars of Parrotia but there are 8 in the 9^th, with two of the new ones I don't know, but also listed is 'Persian Spire' which I do grow. It was introduced by JLPN Nursery of Oregon, a company from Salem where I buy some of my rootstocks. 'Persian Spire' features the most narrow canopy of all, plus it sports fantastic autumn colour. Since it is patented I buy lining-out starts that are produced by rooted cuttings, and this grower can attain an 8' tree in just four years. Another attraction of Parrotia is the late-winter flowers, tiny but numerously-clustered with crimson stamens, an effect similar to the flowering of Acer rubrum.

Davidia involucrata 'Sonoma'

Davidia involucrata 'Sonoma'

Davidia involucrata 'Sonoma'

Davidia involucrata, the “Dove tree” or “Handkerchief tree,” is in the Nyssaceae family, and I only know that because the botanists say so; I never would have guessed myself. The Hillier 9^th repeats the same mistake as the 8^th when it says the cultivar 'Sonoma' was “Selected for its exceptional ability to flower as a young plant, sometimes after only two or three years.” Actually it wasn't, it was selected for its unusually large flower bracts and the early flowering was a later-discovered bonus. I heard the story myself from the California nurseryman who discovered 'Sonoma'. Sales were never great for 'Sonoma', which was a complete mystery for me because there was nothing more delightful than a crop of 7-8' trees, and with every one of them adorned with a couple dozen drooping bracts. Well, I'm not a tree cheerleader so we haven't propagated 'Sonoma' in over five years, and besides, the seedling rootstock is too expensive to speculated on a market change.

Davidia involucrata 'Lady Sunshine'

Davidia involucrata 'Lady Sunshine'

Davidia involucrata 'Aya nishiki'

Davidia involucrata 'White Dust'

We grow other Davidia cultivars with notable features, and a new addition to the Hillier 9^th is 'Lady Sunshine': “A striking form with leaves irregularly margined creamy white. Selected by Crispin Silva, Oregon, USA.” I got an early start from Mr. Silva and mine probably grew to the largest specimen in the world, certainly moreso than the original tree. I sold it to a special customer and made a handsome profit, but my only regret is that I didn't wait long enough for it to flower. Hillier lists only 'Sonoma' and 'Lady Sunshine' for cultivars, but there are others that might eventually make the grade, such as 'Aya nishiki' and 'White Dust', and they actually sell better than 'Sonoma'. Because of 'Lady Sunshine' and the others, the days of selling a straight Davidia are gone for me, and wouldn't E.H. Wilson, who introduced it from China in 1904, find it peculiar, because it was once considered the Holy Grail of trees.

Elaeagnus 'Quicksilver'

Elaeagnus 'Quicksilver'

I always considered the genus Elaeagnus, in the Elaeagnaceae family, to be a crappy group of plants and that no one would miss any of those cultivated if they were totally eliminated from our world. Nevertheless E. 'Quicksilver', named by Roy Lancaster, the VMH plant personality, is a cultivar with a great name, but a plant with problematic characteristics. Having grown it for about 8 years I would highly disrecommend it, and furthermore to actually loath it for its propensity to increase by unwanted, wide-spreading, suckering shoots. I planted my original in the Far East garden, and aggressive growth would quickly pop up as much as 20' away from the original planting. I would describe 'Quicksilver', as does plantsman Roger Gossler with similar bullish plants as: “A thug in the garden.” I was able to eliminate it from my field with herbicides – which I wasn't proud about – but at least it's now gone for good. That the “weed” received the prestigious British Award of Merit is reprehensible, unless the “award” is also accompanied by a plan to contain it. I'll admit that 'Quicksilver' is brilliant in bright sunshine with its vibrant, shiny leaves...with sunglasses recommended.

Salvia 'Hot Lips'

I know very little about the Salvia genus, except it is in the Lamiaceae family and was named by Linnaeus, and Hillier refers to it: “A large genus of 800-900 species of often aromatic flowering plants...” I always figured they would not be hardy for me but my good friend Reuben Hatch had the cute cultivar 'Hot Lips' in his garden in full sun and it has performed admirably for at least 5 years now. Hatch has a lot of fun in his garden, probably more than I do because nothing is a “crop.” I admitted that I liked his 'Hot Lips' and the next time I saw him he bought one for me. I put mine in the ground after a year in the greenhouse, and if it lives – good – and if it dies, oh well. In the Hillier 8^th 'Hot Lips' is considered a cultivar of the x jamensis hybrid (S. greggii x S. microphylla), indicating that both parents are from Mexico. In the 9^th edition it is listed as Salvia 'Hot Lips', and that it was formerly of the jamensis cross. I don't know what to make of the change; is the implication that its parentage is unknown? On the internet it is often called Salvia microphylla 'Hot Lips', the “Littleleaf sage,” and I can see that it's readily available in the trade. As you can see from the photo above it was wonderfully named, and its name reminds me of the Bletilla striata 'Kuchibeni' we grow which means “red lips” in Japanese. Hot Lips, red lips – it all sounds good to me.

Sinowilsonia henryi

According to Hillier, Sinowilsonia henryi is “A rare monotypic genus related to the witch hazels (Hamamelis) and mainly of botanical interest,” and that's because the flowers don't amount to much. Both the generic name and the specific epithet honor two important British actors (E.H. Wilson and Augustine Henry) in the world of botany/horticulture whose petri dish contained a great deal of the flora from China. E.H. “Chinese” Wilson was recruited by the renowned English nursery firm of Veitch and Sons, while Augustine Henry was a customs inspector stationed in China who was probably bored with his imperial duties and so developed an interest in botany and plant collecting. It was Henry who coached and advised Wilson where to find and collect seed of the “Dove tree,” Davidia involucrata. Henry was impressed with the young Wilson, and Henry wrote to a friend that “Wilson was a self-made man, knows botany thoroughly, is young, and will get on.” He added that he “would be glad if [Wilson] will continue to carry on the work in China which has been on my shoulders for some years. There is so much of interest and novelty.” Henry and Wilson stayed close and corresponded for the rest of their lives. It's a litte sad that the one plant that shares both of their names is considered a BIO plant – of botanical interest only – when the floral wealth of China was/is so abundant. Sir Harold Hillier used space in the Sinowilsonia description to pay great respect for E.H. Wilson: “A walk round the nurseries with Ernest Wilson revealed that there was virtually no tree, shrub or herbaceous plant with which he was not familiar. He was a first-class botanist, perhaps the greatest of the plant hunters and, like W.J. Bean, a tremendous companion in the garden.”

Tetracentron sinense

Ernest Henry Wilson

Speaking of obscure Chinese species, both Henry and Wilson were involved with the introduction of Tetracentron sinense, “A large shrub or small to medium-sized tree of wide-spreading habit, a graceful tree from central and west China and the Himalaya,” another tree that was discovered by Henry, then introduced by Wilson. When I first encountered it I assumed it was a robust form of “Katsura,” or Cercidiphyllum japonicum, except the Tetra has alternate leaves. Cercidiphyllum is classified in its own family, Cercidiphyllaceae, while Tetracentron is placed in the Trochodendraceae family, and oddly the latter was once considered a member of the Magnolia family, Magnoliaceae. The botanic name was coined by Daniel Oliver, the English botanist who was Librarian of the Herbarium, RBG Kew, and comes from the Greek tetra meaning “four” and kentron meaning “spur,” referring to four projections of the fruit. A wonderful sweeping-branched specimen can be seen at the Rhododendron Species Botanic Garden in Washington state, and the origin of their tree is from Sichuan, China.

Sorbaria sorbifolia 'Sem'

Sorbaria sorbifolia 'Sem'

Alexander Braun

Hillier indicates that the Sorbaria genus is in the Rosaceae family, which I never would have guessed. The more you learn about plants...the more you have to learn. I have become enamoured with S. sorbifolia recently because I was gifted a plant with the cultivar name 'Sem'. Goodness knows why that name? But the suckering shrub features eye-catching foliage which is best described by Hillier:...”with pinkish and bronze young foliage, maturing to yellow-green and bright green before turning red in autumn.” The foliage is interesting, even if not pink or bronze, and as Hillier says: “Handsome, vigorous shrubs with elegant, pinnate leaves...” Linnaeus named the sorbifolia species, but he put it under Spiraea sorbifolia, but eventually botanist Braun set the record straight. The erect flower panicles appear in July, and one can easily understand the previous Spiraea placement. Botanist Braun (1805-1877) was German, and he was the “leader of the 'natural philosophy' school,” according to www.brittanica.com, “a doctrine attempting to explain natural phenomena in terms of the speculative theories of essences and archetypes that dominated early 19th-century German science.” I think I would pass on joining that club.

Sophora prostrata 'Little Baby'

Sophora prostrata 'Little Baby'

The genus name Sophora was coined by Linnaeus and it is a member of the Fabaceae family with about 50 species. They vary greatly, but I grow only 'Little Baby' which Hillier says is a cross of S. microphylla x S. prostrata. Hillier describes it aptly: “Dense mounds of wiry, zigzagging branches bear small pinnate leaves with tiny green leaflets and small, pendulous, golden yellow flowers.” I think it is hardy to USDA zone 8 (10F) and I had one in the garden for 6 or 7 years until it perished during a vicious winter's cold snap, a very cold snap. Sophora is a legume, a pea relative, and in fact some consider it to be in the Leguminosae family, not the Fabaceae family. Anyway its generic name is New Latin, from Arabic sufayra, a tree in the genus Sophora. An interesting relative in the Fabaceae family is the “Suicide tree,” Tachigali versicolor, which is native to old growth forests from Costa Rica south to Colombia. While it possesses one of the hardest and most dense wood of any Central American tree it is named suicide tree because it dies after fruiting (monocarpic). Within a year the dead parent falls over, creating a gap in the forest canopy that allows its seedling offspring space and a breath of light. This maladaptive strategy – more harmful than helpful – is understandable, don't you think?, because most human parents would die for their children...whether the kids deserved it or not.

The “Suicide tree” didn't make it into the Hillier 9^th because it wouldn't be hardy in the British Isles, although a large number of species that are barely hardy are included in the tome. The SHHG is far more organized, inclusive and scientific than say, the Strybing Arboretum of San Francisco, California, but both gardens leave me with the wish to grow trees in a more benign climate. The Flora Wonder Blog has a readership where I don't know the majority, and it actually has one interesting reader from Singapore, a woman who loves plants, all plants; but that's remarkable because she doesn't grow anything that I write about.

“Talon, whether you write for those in Oregon, San Francisco, England or Singapore, your main purpose is to observe the relationship between people and plants, including yourself. Most of your 'readers' are probably only looking at the photos anyway.”