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A North Wales Alpine Gardener's Diary

This entry: Early June - Entry 45

My last entry was compiled at the end of May and was more than long enough both for me to write and for you to read! However, there were many good plants that I could not mention so I am breaking my normal rule of 'once-a-month only' and producing an interim entry to cover this very busy period in the garden. In any case, my next entry will probably be delayed until mid-July because we are off to the Pyrenees for 10 days at the end of this month; hopefully that trip will give me some worthwile material.

First a few more rhododendrons, some of them much too large for an alpine garden but probably, like me, those of you who have larger gardens than average wish to have some big plants, and what better than some of the larger rhododendrons.The plant of Rh. yunnanense shown here is >20 years old and exceeds 3m high and wide, but it makes a real accent looking down the garden towards the sea on an early June day.It always coveres itself in flowers and is a joy to behold. 

Rhododendron yunnanense

Rhododendron yunnanense

Rhododendron yunnanense close-up

Rhododendron davidsonianum

Anther equally lovely member of the Triflora section is Rh. davidsonianum, named after Dr. W.H. Davidson who collected it while working for Friends Mission China. It seems to be a much more variable species than R. yunnanense, or perhaps it is just that there have been more introductions from a wider range of sites. That shown here is a very pale form given to me as a seedling which was raised from wild collected American Rhododendron Society seed.

Rhododendron davidsonianum

Rh. edgeworthii

Species rhododendrons are grown for their attractive or fragrant flowers, their interesting and even beautiful foliage, or their smooth and glossy peeling bark. Rhododendron edgeworthii is one of the exceptional species in which all of these desirable characteristics come together.This species is the best known and most often grown member of subsection Edgeworthia, a small group of lepidote (scaly-leafed) rhododendrons, which also includes pendulum and the rare seinghkuense, neither of which I have grown. These three distantly related epiphytic species are placed together in this subsection because they all possess a feature unique among the lepidotes – a dense woolly indumentum on the young stems and undersides of the leaves.

R. edgeworthii was introduced into cultivation by Joseph Hooker in 1849. from the lush forests of the Himalaya  during his travels through Sikkim. It was named for Mr. M. P. Edgeworth, then the Commissioner of Multan with the Bengal Civil Service. In 1887 a species similar to edgeworthii but with a scaly style and pubescent (hairy) calyx was found by Pere Delavay far to the east in the mountains of northwestern Yunnan Province, China. This plant was given the name Rhododendron bullatum (because of the deeply impressed leaf veins) and introduced into cultivation by George Forrest in 1904. It proved to be as good as but substantially hardier than its Himalayan cousin. In 1917 the name R. sciaphyllum was given to a specimen collected by Kingdon-Ward in eastern Myanmar (Burma). Subsequent collections throughout the eastern Himalaya, southwestern China,and northern Myanmar made it obvious that all three “species” merged and that the original collections were just extremes from the edge of the large range of a variable species. Thus, all specimens were reassigned to R. edgeworthii with the names R. bullatum and R. sciaphyllum reduced to synonymy. Rhododendron edgeworthii is typically found at elevations of 6,000-13,000 feet in a wide range of habitats (cliffs, rocks, as an epiphyte on large trees) but always with rapid drainage at the roots. 

My 20-year-old plant, which has bloomed exceptionally well this year, is growing in my N-facing moist raised bed with shade for most of the day from a high wall. It receives no special attention other than the usual mulch of leafmould/garden compost after flowering.

Rhododendron edgeworthii

Rhododendron edgeworthii, close-up

Rh. griffithianum

Another of my favourties, also scented, which has been used very extensively (and successfully) in hybridization, is Rh. griffithianum, a splendid large bush/tree, which in my garden has reached 3 x 3m after 23 years from a seedling given to me by Peter Boarcman, raised from seed collected by George Smith and him in E. Nepal. . It is fully hardy on the N. Wales coast but is likely to be tricky in colder climes.

Rhododendron griffithianum

Rh. camtschaticum

I love this diminuitive, deciduous rhododendron so much in the wonderful brick-red Cox form that I now grow that I do not apologise for showing it yet again - one just cannot get too much of some good things!

Rhododendron camtschaticum

Some 'proper' apines

Enough of exotic rhododendrons, let's have a look at a few plants which most of our Members would probably think more appropriate to an alpine garden blog. 

I have grown Paedorota bonorota for many years and have seen it several times in the limestone cliffs of the Dolomites where it is an unassuming but attractive plant. But it has never flowered very well for me until this year and having deigned to do so it is really quite an appealing little plant for a crevice. It is one of only two species in its genus, the orher being P. lutea, from similar habitats in the eastern alps and dolomites, with rather undistinguished straw-yellow flowers. They are close relatives of the veronicas, differing from them in having a five-lobed calyx and and corolla with more-or-less erect lobes arranged as two lips, rather than an open, spreading flower. When seen before the flowers appear this plant can cause a missed heartbeat as the foliage can look very like that of the much more highly prized Physoplexis comosa, which often grows in the same habitat and vicinities.

Paedorota bonorota

Paedorota bonorota

Rupicapnos africanus (syn. Fumaria africana)

This is another plant that I just can't refrain from showing you at this time of year, although I know it may not be hardy in your garden. I find the contrast between the colour, form and texture of the flowers and foliage very pleasing, and it flowers for a good 6 weeks. It is very easy from seed and seeds itself around here, particularly in the sand plunge in the alpine house.

Rupicapnos africanus (syn. Fumaria africana)

Telesonix jamesii and Onosma albo-roseum

These two plants, the Telesonix (Saxifragaceae) ranging in the Rockies from Alberta to South Dakota, the Onosma (Boraginaceae) from the mountains of Turkey, Iraq and Iran, look super draping themselves over  each other and the sides and corner of a raised bed; one of the perennial joys of the garden at this season. Both are easily increased from cuttings of new growth taken after flowering, but beware of the silicon bristles on the onosma which cause severe skin iritation in susceptible people. 

Telesonix jamesii and Onosma albo-roseum

Genista pilosa var. procumbens

Also draping iteself over the edge of the same wall a little further along is an aged and very reliable plant of a prostrate from of Genist pilosa, which is an uncommon British native plant that I have seen on various occasions in Wales where it generally grows on sandy or stony soils - I have seen it on old mine wastes.too. G. 'Vancouver Gold',  which I also grow, is very similar but perhaps a little more vigorous; both may need clipping after flowering to keep them within bounds.

Genista pilosa var. procumbens

Hermannia stricta

It is not often that a plant growing other than in the open garden is shown on these pages, not surprising really as I have few plants growing under glass and most of those are not of high quality, but I am making an exception here for Hermannia stricta, which is flowering well now planted out in a raised bench bed in the alpine house. 

Hermannia is a genus of about 150 small shrubs from southern Africa in the mallow family (Malvaceae), ranging from upright to sprawling prostrate shrublets. They are charachterized by the presence of minute glandular or star-like hairs on the leaves and stems. The stems often have a dark grey bark. Leaves are alternate and entire, lobed or incised. Flowers consist of 5 petals which are slightly or very strongly spirally twisted into an upended rose. Most Hermannia species posess a thick woody stem and root, forming an underground 'stem', which enables the plants to survive dry periods and fires. In the veld, hermannias appear woody, some species being very palatable to stock and browsed down to the main branches. The genus was named after Prof. Paul Herman (1640-1695), a German professor of botany at Leyden and one of the first travellers and collectors at the Cape.

The fact that one of the common names for these plantrs is desert roses gives a clue as to their cultivation and the reason why mine is growing in the alpine house, they require plenty of heat and tolerate drought but are easily killed by too much water. I suppose they are mostly not very hardy either. I have not propagated my plant yet but gather from the literature that cuttings root reasily so muct give it a try.

Hermannia stricta

Hermannia stricta close-up

Silene glaucifolia (syn. Petrocoptis pyrenaica)

And finally for now, a modest but pretty little plant that I had not grown until my friend William Purvis gave me seed last year, Silene glaucifolia, for long known as Petrocoptis pyrenaica). It has grown quickly into the rounded 15 cm x 15cm specimen seen here and I suspect it will not be long-lived, but it is well worth growing - the shade of pink is particulalry clear and bright. I have it growing in a well drained raised bed. 

Silene glaucifolia (syn. Petrocoptis pyrenaica)
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