We would like to find out which species, cultivars and varieties of Grevillea are being grown by our members.
Would you please take a few minutes to answer our survey?
We would like to find out which species, cultivars and varieties of Grevillea are being grown by our members.
Would you please take a few minutes to answer our survey?
The genus Weinmannia was established by Linnaeus in 1759 1 when he named a new plant from a Caribbean island, Weinmannia pinnata. He named the genus after the German pharmacist and botanist, Johann Wilhelm Weinmann (1683-1741) who wrote Phytanthoza Iconographia which was highly regarded for the information and the quality of the 1,025 coloured illustrations. The genus was subsequently placed in a new family, Cunoniaceae, which was established by Robert Brown in 18052.
Most of the new genus and indeed most of the whole family are primarily to be found in tropical and subtropical regions of the world, and thus not widely grown in temperate climates. Only one genus in the family, Eucryphia, is generally regarded as reasonably hardy and widely grown in temperate regions. The distribution of Weinmannia and indeed the other genera in the family is widely considered to relate to Gondwanaland, and hence the evolution of the family has it origins in the Jurassic period, almost certainly before it split from South America3.
The first reasonably hardy species in the genus to be published was Weinmannia racemosa, from the temperate climate in the south island of New Zealand. It was named by the son of Linnaeus in Supplimentum Planatarum, published in 1782, from a herbarium specimen collected on the newly promoted Commander Cook’s second voyage around the world during which he revisited New Zealand, having previously circumnavigated and mapped it on his first voyage. The two botanists on this trip were the Prussian naturalists Johann Rheinhold Forster and his son Johann Georg Forster. It must have been the son who contacted Linaeus fil. regarding the identity of this new tree, as he subsequently published it in his Prodomus in 1786. Father and son had jointly published some of the collections of the trip in Characteres Generum Plantarum in 1775-6.
However, another species had been previously collected from the north island of New Zealand by Joseph Banks and Daniel Solander, the assistant he employed, who acted as botanists on Lieutenant Cook’s first voyage around the world. The herbarium specimen which they collected in 1769 was described in an unpublished manuscript in Bank’s library, by Daniel Solander. Solander was a capable Swedish botanist and student of Linnaeus. He died at the early age of 49 of a brain hemorrhage in 1782, whilst still in the employ of Banks as secretary and librarian. For the last 10 years of his life he was also employed as Keeper of the Natural History Department of the British Museum. Solander’s name and description of the new plant, Weinmannia silvicola, was eventually published by Alan Cunningham in 18394 along with other plants which the latter collected in the North Island of New Zealand in 1926.
The hardy species Weinmannia trichosperma was first described and published the Spanish botanist Antonio Cavanilles in 18015. Whilst he gave no indication of who collected the new plant Luciano Barnardi indicates that the herbarium specimen was collected by Joseph Dombey, who accompanied Ruiz & Pavon on their expedition to Chile and Peru6. (The politics and convoluted circumstances of that expedition are briefly described by Alice Coates7 and in a more understated scholarly way by F.A. Stafleu8.) Apparently unaware that Cavanilles had described and published the plant, based on the Dombey herbarium specimen, Ruiz & Pavon published the same plant under the name Weinmannia dentata a year later9.
The earliest record of any species of Weinmannia growing in the British Isles was W. racemosa in ‘A list of plants hardy in the Gardens at Castlewellan in 1903’10 in the sheltered arboretum created by the Earl of Annesley, in the south of County Down. However, it was not included in the paper he gave to the RHS in July 190211 which was an overview of many of the fairly mature ornamental trees and shrubs growing there, but was by no means a comprehensive coverage. How long it survived is not known, but it was certainly not listed in a small catalogue of plants in the garden published in the 1970s.
The next published record of Weinmannia was the result of ‘Meeting of the RHS Scientific Committee on 11th April 1917’, chaired by E A Bowles, which decided to conduct a survey of how many plants in the British Isles had fared after the previous very severe winter. The results were published in 191812. Only two of the many gardens contacted and responded grew Weinmannia. W. racemosa was unaffected at Rostrevor House, at the south-eastern extremity of County Down; the sheltered garden and very significant plant collection of Sir John Ross of Bladensburg, which was well known to leading botanists and plantsmen of the day. W. silvicola was recorded as been killed to the ground at Glasnevin Botanic garden in Dublin. Whether it recovered is not known. However, Glasnevin may have had the foresight to pass a duplicate of this tender plant to Tresco in 1914, where it was recorded as still growing at Monument Walk in 198513.
It was 1921 before there was any published reference to Weinmannia trichosperma being in cultivation. It was contained in a substantial list of South American plants introduced into cultivation, compiled by W.B.Turrill MSc, at the request of Mr W.G. E. Loder MA, F.L.S. F.R.H.S, but without giving any details were the plants were being grown or by whom14. It was probably compiled as an intended acquisition list for Mr Loder, who was an avid collector of plants. Six year later W. trichosperma gained an AM when a flowering branch was put up for award at the RHS by Mr G.W.Loder Esq., the year before he became president of the RHS15.
In 1930, Edgar Thurston recorded W. trichosperma as growing at Lugdvan rectory and in the temperate house at Kew, but without further details. 16 Curiously he did not mention it growing at Lanarth. The year before, Frank Kingdon Ward, writing about a visit to Canon Arthur Boscawen’s garden at Lugdan rectory in the summer of 1927, extolled the virtues of late flowering trees and shrubs from Australasia, and New Zealand in particular, but almost dismissively noted W. silvicola and W. trichosperma as being other interesting plants17.
The first published record of a substantial tree of W. trichosperma is of one being 20ft (6.1 m) high in 1931 at the garden of P.D. Williams at Lanarth, albeit published only a decade later18. The origin of these early introductions does not seem to be known, but the tree at Lanarth, judging from its height, may have represented the first introduction of the plant into cultivation, prior to 1920. As Bishop Hunkin recorded in and article on Lanarth, P.D. Williams received plants from a wide circle of leading gardeners and plantsmen. The plant could well have come from Canon Arthur Boscawen. Curiously, Arnold-Forster only mentions W. trichosperma in the final chapter, Uncommon, untried or tender shrubs, with a brief description and rather dismissively refers to the New Zealand trees as ‘other species, less attractive’19.
The first record of Weinmannia being collected in the wild is by Harold Comber, on the second of his two Andes Expeditions in 1925-6 and 1926-7. He collected the seed (No.1060) at 3000ft (915m) on the Argentinean side of the border beside Lago (lake) Lolog, with an XX rating, XXX being the most garden worthy, and no rating the least garden worthy. The accompanying note reads: ‘Here only a narrow belt by the water’s edge, 12’-25’high, but with big trunks. Slow growing and stunted, but shows no sign of being frozen. Should be hardy. Germinated’20. The introductory note accompanying the collection data, written by Henry D. McLaren, notes that the seeds were identified by Kew from herbarium specimens of the plants collected, and that both RBG E and Kew were presented with a set of seeds by the Subscribers, who comprised many leading affluent gardeners of the day.
Not many examples of Weinmannia seem to have survived from this introduction, and only two possible plants might be from this collection, the current Champion tree in the British Isles21 at Mount Stewart, Co Down (52ft (16m) x 12” (31cm) dia in 2003) and a potentially close rival, at Logan Botanic Garden on the Stranraer peninsula (45ft (14m) x 10” (24cm) dia. in 1979), though its tree would have been planted before RBG Edinburgh took over responsibility for it. The Mount Stewart specimen was first mentioned in print by Graham Stewart Thomas in 1950, when he saw it there growing beside the lake in full flower, at 25ft high22.
Perhaps, surprisingly Bean only mentions two specimens, though does include a line drawing of the attractive fern-like foliage23. The first, a 12ft (3.5m) high specimen, at Wakehurst Place, which must have been a replacement for the plant which Gerald Loder, later elevated to become 1st Baron Wakehurst, got the AM for. (The current specimen growing there at 16ft (5m)21 must be another replacement or else the plant has been remarkably slow growing for almost 30 years.) The second specimen mentioned by Bean was the champion tree (59 x3 ¾ ft girth in 1971) at Tregothnan in Cornwall, the estate and garden of Viscount Falmouth, which has been in the Boscawen family since 1344. That tree, now presumed lost, almost certainly came from Canon Boscawen, cousin of the then 7th Viscount, who was known to have supplied plants to the family estate.
What is surprising is that such an attractive tree as W. trichosperma is not more widely grown, despite being in cultivation in the British Isles for almost a century. The rarity of W. silvicola is not so difficult to explain as it comes from the north island of New Zealand. It is probably only on Tresco that it would survive for any length of time as it requires very mild temperate conditions. W. racemosa, again barely in cultivation, is certainly hardier, and it is puzzling as to why no examples of it were identified in cultivation in the recent survey by Owen Johnson21.
It must be admitted that neither of the New Zealand species are as attractive in leaf as their South American relatives. The juvenile foliage of W. silvicola (locally called Tawhero) is pinnate but reduces to trifoliate and even simple leaves in maturity. The tiny white flowers are presented in racemes, clustered at the tips of the branches and the trees can vary in height from 20ft (6m) to 70ft (22m), and develop a trunk up to 3ft (90cm) in diameter24.
The juvenile foliage of W. racemosa (locally called Kamahi) is simple or trifoliate, becoming simple in mature trees (photos pages 20and 21), which can reach a height of 90-100ft (28-30m) with a trunk up to 4ft (1.2m) in diameter. The slightly larger flowers are presented in longer racemes, but with fewer clustered at the tips of the branches24. The flowers of both trees are illustrated in several books on native plants or flora of New Zealand25 as well as being easily found on various websites.
I have not been tempted to try growing W. silvicola for obvious reasons, but have grown W. racemosa for about 10 years. A small seedling about 8in (20cm) tall was planted out in rather dry, poor and fairly shallow soil over dolerite bedrock. It proved to be rather slow growing, which is perhaps not surprising given the conditions in which it was planted. However, it has survived and established itself, despite competition from several large eucalyptus species, which, I learnt rather too late, tended to reduce soil fertility. That should have been obvious, as eucalyptus leaves do not rot down easily. In the last couple of years the rate of growth has increased and, aided with a top dressing of horse manure last year, growth rate improved a little and the small tree has now reached 8ft (2.4m) high (photo page 21). How long it will take before starting to flower remains to be seen.
In contrast to the New Zealand tree, W. trichosperma (locally called Teniu, Maden or Medehue) does not have a different form of juvenile foliage. The small white flowers are similarly presented in short racemes, either singly in pairs or in groups of 3-4, though not at the tips of the branches; they normally occur either side of new leaf growth (photo page 22). Again it can reach 100ft (30m) tall, but so far rather less in cultivation. In Chile it occurs in two almost disjunct linear areas either side of the highest ranges of the Andes, approximately from almost 37o to 45 o south26 (regions VII to XII). Plants from the coastal habitat including Chiloe island and further south on the mainland are likely to be less hardy as those growing at higher elevation inland along the border with Argentina.
The tree that I grow is now about 15 years or so old, and has reached about 20ft (6m) high, It is in slightly deeper and moister soil than its New Zealand cousin, though not necessarily more fertile. It is a seedling from the Mount Stewart plant, but unfortunately there is no specific reference in the sporadic garden notes to identify its provenance or date of acquisition. The Mount Stewart tree grows in a relatively open position beside the path close to the lake, and forms a neat narrow tapering spire, but unfortunately it is not possible to get a good photograph of it, without being able to walk on water. However the small pinnate leaves really need close inspection to appreciate their intricacy. When flowering well, the flowers can give the impression of the tree being well dressed with a mass of short white candles, albeit rather drunkenly arrayed. The new foliage (photo page 22) makes a colourful contrast to the dark glossy green mature foliage and is echoed later by the seeds turning red, before ripening to brown. Its normal flowering period is in May, though in 2010 for the second time it has produced a second crop of a few flowers, in October and into November, though not so many as in 2008 when it previously provided an autumn flush of flowers, but without detracting from the display the following spring.
Whilst W. trichosperma is not especially showy it has an understated elegance which ensures that it should be more widely grown. It is not wide spreading so does not need a lot of space and could readily be planted instead of some conifers or other evergreen trees. However, it is only suitable for growing in the more westerly areas of the British Isles, where reasonable rainfall, and relatively high humidity usually prevail. It is probably best planted in moisture retentive soil, and can tolerate light shade. It can be raised quite easily from the fine seed which is best almost surface sown in close conditions to maintain a high humidity. Care should be taken to prick out the seedlings when still quite small and to pot in into relatively heavy potting mix to ensure the roots are not disturbed when potting on or planting out in its permanent position. Root disturbance of relatively small plants can prove fatal.
Author: Gary Dunlop
Published: Issue 46 (May 2011)
1. Linnaeus, C. 1759: ed .10 Systema Naturae p.1005
2. Brown, R. 1810: Prodomus Florae Novsae Hollandiae 1802-5
3. Bradford J.C. 1998: A Cladistic analysis of species groups in Weinmannia (Cunoniaceae) based on morphology and inflorescence architecture p. 582 Vol.85 pp.565-593 Annals of Missouri Botanic Garden
4. Cunningham, A. 1839: W.sylvicola (Sol.) Annals of Natural History Vol.2 (11) p357
5. Cavanilles, A 1801: Icons et descriptions Plantarum Vol. 6 p.45 tab.567
6. Barnardi, L. 1961: Revisio generis Weinmanniae. Pars I: Sectio Weinmanniae. Candollea. 17: 123-189.
7. Coates, A. 1969: The Quest for Plants. pp.363-8 Studio Vista, London
8. Stafleu, F.A. 1963: L’Hertier de Brutelle: The man and his work pp.xx-xxiv in Lawrence, G.H.M. 1963 ed. Sertum Anglicum 1788 Facsimilie with critical studies and a translation. Hunt Botanical Library, Pittsburgh.
9. Ruiz & Pavon 1802: Flora Peruviana et Chilensis Vol.4 . tab. 334
10. Annesley, Lord 1903: ‘A list of Plants Hardy in the Garden at Castlewellan, Co Down. Privately published
11. Annesley, Lord 1902: On ornamental trees and shrubs in the garden at Castlewellan Co Down Ireland. RHS J Vol. 27 pp 407-27.
12. Bowles, E.A. 1918: The effect of the frosts of the Winter of 1916-17 on Vegetation. RHS J Vol 43 pp.388-461.
13. King, R. 1985: Tresco England’s Island of Flowers. P.160 Constable London
14. Turrill, W B 1921: Plants introduced to horticulture from Chile and Argenntina (including Patagonia and Fuegia). RHSJ Vol.46 pp.346-50.
15. Floral committee 1928: AM to Weinmannia trichospermum (12 votes for) [out of 26 members present at Chelsea May 24th 1927] from G.W.E.Loder Esq. Ardingly. A tender shrub bearing fern- like leaves and terminal racemes of small white flowers. RHSJ Vol.53 p.lviii
16. Thurston,E. 1930: Trees & Shrubs in Cornwall. Cambridge University Press for the Royal Institution of Cornwall.
17. Kingdon Ward, F. 1928: Ludgvan rectory. Gardeners’ Chrionicle March 9th 1929 pp 183-4.
18. Hunkin, Rt Rev J W 1945: The Making of Lanarth RHSJ Vol 70 p.108 (pp.63-72, 104-10 & 132-5.)
19. Arnold-Forster,W.1948: Shrubs for Milder Counties. p.348 Country Life, London
20. Comber, H.F. 1927: Field Notes of Plants collected by H.F.Comber. Andes Expeditions 1925-6 and 1926-7. Privately published.
21. Johnson, O. 2007: Half Hardy trees in Britain and Ireland. Only produced in electronic form on CD, available from the Author and a copy at the Lindley Library. See also The Plantsman 2008 Vol.
22. Thomas, G.S. 1950: Some Famous Irish gardens Pt.1 pp.236-251 RHSJ Vol.75
23. Bean, W.J. 1980: Trees and Shrubs hardy in the British Isles. Vol.4 8th revised edition. John Murray London.
24. Kirk, T. 1899: The Forest Flora of New Zealand. pp131-2 & Plate 72. & pp.133-4 & Plate 73. Government press, Wellington.
25. Cave,Y, & Paddison, V. :Encyclopaedia of native New Zealand Plants. p.49. Random House, Auckland.
26. Zegers, C.D. 2005: Arboles Nativos de Chile [Chilean Trees] pp.60-1. (Bi-lingual text) Marisa Cunero Ediciones Valdiva.
There are over 900 rhododendron species. The genus is split into several subgenera, one of which is called Vireya. One of Vireya’s characteristics is the presence of scales on the leaves, stems, flowers and fruits. The purpose of these scales is not known but a possible explanation is that they help to protect the plant from the strong solar radiation on the tropical mountains where they are found.
The first mention of an Australian rhododendron was when Baron von Mueller collected and named Rhododendron lochae on the Bellenden Ker range, inland from Cairns in Queensland. Nowadays the specific name, which commemorates Lady Loch, then wife of the Governor of Victoria and a patron of horticulture, is spelt lochiae. The first account of R. lochiae being cultivated was in the Gardeners’ Chronicle in 1939, where it was reported as growing at Kew. In 1953 Rhododendron lochiae appeared in the catalogue of Basil Hodgkins, at his nursery in Essendon, Victoria. It quickly became popular and was used as a parent of many hybrids.
In the early 1990s it became apparent that two different plants were being grown and sold as R. lochiae and the botanist Lyn Craven discovered that the Hodgkin plant was new to science. To change its name would have caused much confusion in horticulture all round the world, so Craven created a new type species and called the von Mueller plant R. notiale (meaning from the south). Unfortunately this action did not meet with the approval of international botanists so it was renamed R. viriosum, while the von Mueller plant remained as R. lochiae.
When not in flower the two plants are indistinguishable but in bloom they are easily separated:
R. lochiae has a curved floral tube, with the stamens on one side. This indicates that it is pollinated by birds.
R. viriosum has a straight floral tube, with the stamens arranged in a circle (see photo page 20).
It is possible that further species remain to be discovered in the mountains of North Queensland.
In the wild these plants grow both as epiphytes and on the ground, on steep slopes, and in rich soil with much organic matter. They are subject to frequent heavy downpours of rain and the cool mountains on which they are found are often misty. Although growing in acid conditions, they have a high requirement for calcium.
I have found that they can be grown in leafmould and in a mixture of equal parts of coarse and fine bark. Calcium was added as baking powder (it contains acid calcium phosphate). Temperature is also important. Temperatures below 5°C result in dark spots on the leaves, which also lose their gloss. A winter minimum of 10°C is recommended. The compost must never be allowed to dry out, yet must be very well drained.
Seedlings bloom in their third year and for me that has been in August. However at the Tatton Park Flower Show R. viriosum has been shown in bloom in late July.
Author : Jeff Irons
Published: Issue 47 (December 2011)
Seeing the picture of acacias on the Algarve on the cover of the May 2009 Pentachondra prompted me to write this article about Acacia dealbata.
A. dealbata is confined to Tasmania, Victoria, New South Wales and the Australian Capital Territory where it has the common name of Silver Wattle. In the United Kingdom it is called Mimosa or Florists’ Mimosa and it used to be sold in posies or bunches by florists and even from street barrows in London. Flowering branches came into England from southern France but it is many years since I saw Mimosa on sale. Whilst much admired as a cut flower in Europe, in Australia it is considered bad luck to bring cut branches in flower into the house.
In southern parts of Australia it can make a shrub but more often it is a tree, especially in Tasmania where it can reach or even exceed 100 feet (30 metres). Most species of Australian acacia have their leaves replaced by phyllodes which are hard and spiny (see Jeff Irons’ article on the botany of Acacia in Pentachondra December 2008, page 8). Acacia dealbata has true bi-pinnate leaves which are silvery-grey, hence the common name. New stems and young leaves have a silvery pubescence which intensifies the leaf colouring. There are forms in which the leaves are glaucous rather than silvery, becoming almost blue in some selections. It was the blue leaved forms that were favoured by florists. In my experience, these forms are less hardy than the silvery grey ones.
Flowering occurs in winter or early spring. The yellow spheroidal heads of tiny fragrant flowers form large panicles. In the open this species tends to be tender and has not been reliably hardy in Britain except perhaps for the south west. But after 20 years of mild winters it might well be that it has become more widely established and plants have grown to flowering during that period. Flowering is variable and is dependent on summer warmth in the year before flowering.
My experience of it in southern England was in the earlier decade of the 1980s when cold winters with snow were frequent. I raised saplings from a range of wild collected seed from many sources. These were planted at the foot of a high south facing wall with most being killed off during the first winter. If they survived this stems were thicker and roots had penetrated deeper and as a result these saplings were more likely to survive the next winter. My best result was with saplings raised from high altitude Tasmanian seed. One of these survived for four winters and reached a height of 15 feet (nearly 5 metres) only to be killed in the next.
Wattles are easy to raise from seed. Pour boiling water over the seed and allow it to remain in the cooled water for 24 hours before sowing. In my experience A. dealbata requires an acid soil and yet one can read in books that it will tolerate some alkalinity. Most usually, even in the milder winters, shrubs/trees will be grown against a south facing wall and this needs to be of considerable height.
A memorable experience, from when I was flying over Tasmania in winter on a journey from Melbourne to Hobart, was to see through the portholes mountain tops which were golden with the flowers of Silver Wattle.
Author: Brian Halliwell
Published: Issue 43 (December 2009)
Early travellers along Tasmania’s rivers often saw what looked like the top of a bunch of celery sticking up above the general rainforest canopy. They called the tree that bears it Celery-top Pine. Botanists took a different view and thinking that the foliage resembled that of a Spleenwort, gave it the specific name aspleniifolius. They put it in the genus Phyllocladus.
So the botanical name of Celery-top Pine is Phyllocladus aspleniifolius. The Greek word for leaf is phyllon and that for branch is cladon. So the name, daunting at first sight, actually tells us that the flattened branchlets (cladodes), which contain chlorophyll, have taken over the function of the leaves and that the cladodes themselves are shaped like the frond of a Spleenwort (see photo page 9). The true leaves are minute deciduous scales, seen along the edges of the cladodes.
Plants can either bear flowers of one sex only, or can have separate male and female flowers. Often in clusters of 3 or 4, the flowers are borne on the cladode edges and the fruit, like that of a yew, is a small nutlet surrounded by a fleshy aril. Scale bracts at the base of the fruit turn pink or red and swell so that they partly enclose the aril, acting as bird attractants.
Phyllocladus used to be found over a large part of S.E. Asia but today there are only four species, one in Australia and New Zealand and three others in Malesia. They are not pines (Australians give that name to all conifers) but are actually in the southern family Podocarpaceae.
Celery-top Pine is a tree with a straight bole and no buttresses. Although it can be up to 30 metres high, specimens of less than 20 metres are quite common. Needing moist acid soil, in the wild it grows in conditions with cold winters and cool or humid summers with an annual rainfall of 1000-3000 millimetres. Seedlings have long narrow true leaves and quite quickly the new foliage is cladodes, not leaves. Like legumes and casuarinas the tree has a mycorrhizal association which enables it to utilize soil nitrogen, so seedlings should be put into a compost containing unsterilized soil and there are obvious implications for cuttings.
Nowadays it is confined to Tasmania, with a dwarfed subspecies alpina in New Zealand. This latter plant has a green ‘leaved’ and a glaucous ‘leaved’ form. Both can be found in British gardens. As pot specimens they enable gardeners with small gardens or alkaline soil to grow this delightful, handsome and desirable tree.
Author : Jeff Irons
Published: Issue 43 (December 2009)
Sturt’s Desert Pea (Swainsona formosa) is one of the iconic plant species of inland Australia, and is the floral emblem of South Australia. In the wild it can produce massed displays of extraordinary scarlet flowers, usually having a glossy black central boss.
The photograph on the front cover, taken in August 2006, shows one such display in the Cape Range National Park in Western Australia. It is worth noting that many populations in that park lack the glossy black boss on the flowers.
It is reputed to be fairly easy to cultivate in hot climates. I guess it has been cultivated in Britain occasionally, though I am not aware of any reports of this. It seemed to be an interesting challenge….
I bought a small packet of seed in Australia in 2006, and decided to give it a go this spring. The seed germinated well and rapidly using the bog method on an indoor windowsill, without any pre-treatment of the seed, following sowing on 5th May. The young seedlings transplanted well into a peat-based compost containing 30% perlite, and grew on in the greenhouse. Then slugs discovered them (even in the greenhouse!). I transplanted the surviving plants into 2 litre pots (both clay and plastic) containing a similar, well-drained, soil-free compost. The plants that had survived the slugs grew well initially, but many succumbed to root rots in the dank conditions in July and August. Two plants initiated flower buds during August, and one of these flowered in early September. This plant made a spectacular display on our kitchen windowsill before it too succumbed to a root rot. These flowers too had paler bosses than normally seen in the wild, but the red colouration was superb.
With hindsight, and having read more on the cultivation of this species, I may have achieved better results had I used a free-draining inorganic compost at transplanting. And I am sure I would have seen better growth had there been more sun this summer! Nevertheless, my experience does show that Sturt’s Pea can be grown to flowering fairly easily, and I’ll try again.
Author: John Purse
Published: Issue 41 (December 2008)
I have to start by confessing that I am a Restio addict. I have been growing Restios from seed and buying plants when and where available for the past 8 years. I now have 34 different species. 30 of which come from South Africa, 3 from Australia and 1 from New Zealand. I find it easy to source seeds from South Africa but far more difficult to source seeds from Australia and New Zealand.
The Restionaceae is a family of rush like plants largely from the southern hemisphere. They are valued for their great form and year round presence. Many of them make great cut foliage, with individual stems that can last for months in water. They have become popular in the florist cut foliage industry.
They are not easy to germinate. Best germination comes when seeds are treated with ‘instant smoke’ prior to planting, and when they experience a marked difference between day and night temperatures after they are sown. After germination I place the seed tray outside in a sunny, windy position. During their first year the seedlings look very different from the adult plants and have numerous finely branched sterile culms. In the second winter a new set of culms is made usually with the seedling morphology and the first year’s growth dies back. Only in the third year do the plants reach the typical adult form.
All Restionaceae are dioecious (male and female flowers are borne on separate plants) and are wind pollinated. I am experimenting at the moment having planted a male Elegia capensis upwind of a female Elegia capensis, I have gathered the seed and will be sowing it shortly and hoping that it is viable! Given sun, lots of air movement (which is never a problem in our coastal garden) and lots of water Restios grow very fast. They prefer acid soil of low fertility and hate phosphorus. They also hate root disturbance and can sulk for 2 years or more if moved or worse still split!!!!!!!!
Identifying Restios is a nightmare as is their names.
The Australian Restios I am growing are Baloskion australe (was Restio australis), Baloskion tetraphyllum (was Restio tetraphyllus) and Tremulina tremula (was Restio tremulus). The names were changed as the taxonomists decided that the Australian Restionaceae family was totally different from their South African cousins. Certainly the South African Restios I am growing on the whole are much larger and robust than the Australians I am growing, but then I only have a very small representation of the Australian plants. The sole New Zealand Restio I have is Leptocarpus similis and only one seed germinated so it is being carefully monitored.
I would love to try more Australasian Restios and would be very grateful for any information on seed sources in Australia and New Zealand.
If you do not have acid soil Restios can make stunning accent pot plants given the required sun, air movement and plenty of water. As they are fast growers they will need to be potted on frequently, but they look so good all year round unlike some other members of the grass family.
Author: Phemie Rose
Published: Issue 40 (May 2008)