As observed during February 2008
4/2/2008
A Himalayan treasure
Various forms of Daphne bholua are planted throughout the Garden. The earliest to flower is towering up 5 metres from the sheltered courtyard to the north of the Glasshouses Front Range. Carefully lean over the railings and breathe in the heavy scent exuding from this plant. The flower clusters terminate last year's growth, a light violet in bud, opening white.
This plant is native to the Eastern Himalayan mountain range and is found as an understory plant beneath Tsuga dumosa forest, with evergreen Magnolia and Quercus sp. The image shows a plant with white flowers in November on the road from Dochula, Bhutan at c.2900m where views to the snow capped summits of the Himalayan peaks border Tibet. As with cultivated specimens, the evergreen leaves have a chlorotic appearance to the edges which are prone to curl in on themselves.
The flower colour within the species is variable and the plant growing to the west of the Orchids & Cycads glasshouse is very lightly shaded pink in bud. From a distance, the overall appearance is of a mass of white bloom. This plant is one of the seedlings collected at an altitude of c.3000m by Peter Smithers on the Daman Ridge, Nepal.
Another collection from Eastern Nepal, growing at a slightly higher elevation c.3200m, was made by Spring-Smyth, who was an officer in the Gurkha regiment. His find was given the cultivar name 'Gurkha'. Differing from the evergreen type species this cultivar flowers on deciduous wood. 'Gurkha' has fusty purple pointed buds. These elongate and emerge from a sheath of sepals as terminal clusters on the previous year's growth. This growth is highly polished wood pitted by leaf scars. A good specimen grows in the south-facing border adjacent to the Alpine House. Again, as if to prove the variation within the species, this has an overall deep pink appearance and an upright form of growth.
Avoid standing or walking on cultivated soil when appreciating these plants. Constant foot traffic over cultivated areas will result in compaction and loss of pore space in the root zone resulting in a reduction in vigour of the plants.
8/2/2008
An alpine odyssey
This week has brought lengthening days, warmth from the sun and bud burst from many of the dormant clumps of herbaceous plants throughout the Garden - all signs that spring will soon be with us. It may take longer for the soil to warm up this year on account of the increased rainfall we in Edinburgh have experienced this January, a total of 167.1mm. This compares with the past 19 years' average of 72.8mm. Sunshine levels have also been low which may be due in part to rain having fallen on 26 of the 31 days of January 2008.
This week the Alpine House is worth a visit. Of special mention is Helleborus thibetanus, a native to China originally discovered by Pere Armand David in 1869 in Sichuan Province but not introduced to cultivation until the 1980s.
A choice plant rarely seen in cultivation, it bears light pink petals in globose hung form on a stalk of 150mm. Within the head are a ring of fresh green nectaries. The leaves have red thread veins running from the leaf stalk into the divided leaflets. The watercolour-washed green surface of the leaf is imprinted with a textbook true network of veins. A saw tooth edge from the leaf tip running two thirds of the length completes the picture of a choice member of the family Ranunculaceae.
Also providing colour on the south side of the alpine house are representatives of the spring flowering bulbs and corms; Narcissus, Crocus, Cyclamen; Gymnospermum, Ranunculus, Corydalis and a promise of a good show from Primula allionii are also present, all pot grown and sunk into the raised benches of sand to maintain a cool root zone.
14/2/08 
Rose - a thorny issue
Rosa sericea ssp. omeiensis forma pteracantha - the longest sequence of names and the most decorative of thorns are this plant's claim to fame. As there was no possibility of finding a bunch of twelve red roses in bud in the Garden, this species will have to suffice representing St Valentine's Day.
R. sericea has a distribution range through the Himalayas into seouth-west and central China. Our specimens were collected on the Sichuan expedition of 1997.
As can be seen from the two images, the broad, flattened spines are variable in colour, shape and size. In colour they vary from near translucent to a dull brown through many attractive shades of red. The stems are often populated with a multitude of small spines.
This strong-growing rose is best pruned to allow young shoots to regenerate from the base of the plant - the young wood produces the best stem and spine colour. As the wood ages, the colours depreciate in their intensity.
18/2/2008
An early currant
An evergreen shrub with leathery leaves, Ribes laurifolium is a native of west China, introduced to Britain in 1908 by Ernest Wilson. The flowers are produced in racemes that elongate pendulously over a week of warm weather to 75-80mm in length. When in tight bud, these are more attractive than the extended inflorescence at maturity.
The flowers take on a white appearance en mass, however each of the five petals and central boss has a distinct lime-green shade. These are fused at the base from where the single sepal arises, acting as a shield to the individual flower.
Planted opposite the Arid Land House, tucked away on a south-facing wall beneath a canopy of vegetation, this evergreen is thriving on dappled sunshine. The nectaries at the base of the individual flowers are glistening with liquid, sweet to the taste. In the nectar pool are splashes of orange colour, invisible to the naked eye, resembling vestigial anther heads. Most descriptions of this plant describe it as dioecious, that is male and female flowers produced on separate plants. In these images, taken through a light microscope in the Garden's SEM Suite (6.5 x magnification) by Frieda Christie, distinctive anthers can be seen, held free from the petals with a short filament strand.
The plant is slow to establish but will grow to about 1.8 metres with weak woody shoots when cultivated successfully. It is best grown through or up a support, allowing the pendulous flowers to be seen to full advantage.
25/2/2008 
A choice plant from the coastal mountains of Chile
Latua pubiflora is not to be missed. Possibly one of the choicest plants to come out of recent plant collecting expeditions to Chile. This introduction is from the joint University of Chile, RBGE expedition during 1998.
It was noted as an unprepossessing plant with yellow fruit found growing as a spiny shrub to 2.5m in alluvial gravel deposits on the eastern bank of the Rio Quihuis in the Los Lagos region of coastal mountains within Southern Chile. Growing at an altitude of 140 metres on a sparsely vegetated river bank.
Called "El Loco" as it is highly toxic when ingested, as is typical of many Solanaceae family members.
.jpg "Close up of the gloriously coloured flower")
Staged opening of the flower buds occurs. These appear from the dormant growth buds and expand to 40mm into tubular corollas with a 5 pointed splayed end beyond which the extended stigma protrudes. The buds are encased by dark purple sepals which are forced open by the extending bright purple corolla tube. Hidden within are the 5 anthers held on filaments, the base of which are covered in fine white hairs.
Here in the nursery it reaches 4 metres as a very healthy strong growing deciduous shrub. As the girth of the main stem increases the bark splits revealing fissures, dark green and brown in colour. As previously mentioned it is spiny, these are prominent and extremely vicious spines. The growth can be managed by cutting back to ground level after flowering in April. This will give rise to the prolific production of watershoots from the pruning cuts. If this is done every six years the plant will remain manageable. Our plant, now ten years old has great vigour and a wide spreading head.
Young plants growing in a nursery bed can languish for several seasons then vigorous shoots will sprout from the base of the plant and reach 1.3 metres during the course of a single growing season. Could this be the hedging plant of the 21st century; reliably floriferous, barbed to repel, and responding positively to pruning cuts?
For a detailed description of Latua pubiflora read the article by Martin Gardner and Sabina Knees in The New Plantsman September 2000; Vol 7 Part three, pp.184 - 190.
29/2/2008
Spring bulbs and leaf mould
Spring bulbs are making their presence known; the Crocus cultivars are in flower on the west slope from Inverleith House and at the east gate. Groups of Narcissus bugei from Spain and Scilla mischtschenkoana from Turkey, Iran and the Caucasus in the demonstration garden and alpine area. Miniature Narcissus cyclamineus, Leucojum and Iris in the Rock garden.
The arrival of warmer weather also heralds the appearance of the green cotyledons of germinating weed seeds. Now is the time to spread material from the compost heap as mulch over cultivated soil to smother these before flowering stage is reached and a potential further generation of seed is produced.
The diamond geezer of organic matter is leaf mould. In the Garden we collect the leaf fall from the previous autumn; store and by turning regularly produce crumbly, friable leaf mould. This is returned to cultivated areas of the Garden as mulch increasing the humus content of the soil.
The image illustrates the different rate of breakdown of the softer cellulose tissue compared to the lignin within the leaf. Deciduous leaves decompose faster than the more leathery resilience of the evergreen species. All will make ideal feedstock for the leaf heap. Check around border edges where leaves congregate over winter and rake out to allow grass to recover.
