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Wednesday, May 20, 2015

Begonias Part II - Borneo’s wild varieties

By: Anthea Phillips 

LAST week I wrote about begonias in general – common pot-plants that can be easily grown on your porch, a shady windowsill, or in a damp corner of your garden. 
The commonest begonias grown in Sabah are cultivars belonging to the Begonia rex x cultorum group that I mentioned last week, often with beautifully patterned leaves, whose ancestors are tropical Asian species. 
There are, however, many wild species of begonia in Sabah as well. According to the recently published “A Guide to the Begonias of Borneo” by Ruth Kiew, Julia Sang, Rimi Repin and Joffre Ali Ahmad, almost 200 species have been described from Borneo. 
Eighty-two of these are recorded for Sabah and almost half of those were only described in April this year in the journal of the Sabah Forestry Department, “Sandakania”! 
Celebration of Sabah Begonias!
Sabah’s begonias are diverse and beautiful plants. Many of them are also rare, found in very restricted localities. While several are found on sandstone soils in the mountains, others prefer acid limestone soils and are found only on one or two isolated limestone outcrops, where they are already endangered due to hill quarrying and other habitat destruction. 
These wonderful species deserve to be better known in the hope that they will be protected in their natural habitats as well as in cultivation, at our native orchid centres such as Poring Hot Springs, Kipandi Park, the Sepilok Discovery Garden and the Tenom Agricultural Park. 
This, then, is a celebration of some of the Begonias of Sabah! 
The Sharp-leaved Begonia
Discovered in 1984, the Sharp-leaved Begonia, (Begonia amphioxus), is an unmistakeable, shrubby species, found only on two limestone outcrops in the remote Batu Punggul area of southern Sabah. It has distinctive, narrow, bright green leaves, pointed at both ends, which are covered in striking crimson spots. The name ‘amphioxus’ is derived from the Greek, meaning ‘sharp at both ends’. 
The Pink-spotted Begonia
The Pink-spotted Begonia, (Begonia malachosticta), with leaves covered in bright pink spots, (though these can turn white in older leaves), comes from the Gomantong caves (better known for their bird nests!) on the east coast, while the name comes from the pink flowers of the Mediterranean Mallow, (‘Malacho’), and ‘sticta’, meaning ‘spotted’. 
Dewol’s Begonia
Begonia dewollii, with its delicate pale pink flowers, is from limestone hills along the Kinabatangan river, also in eastern Sabah. The round fleshy leaves, plain green above and red beneath, with slightly wavy margins, grow tightly pressed against the rock surface. 
This species is named after Dewol Sundaling, a former Senior Herbarium Officer at the Forestry Department in Sandakan. 
Lamb’s Begonia
Lamb’s Begonia, (Begonia lambii), though rare, has a more widespread distribution, having been found both on the limestone of the Batu Punggul area and on the sandstone of the Maliau Basin in southern central Sabah. 
It grows as a low rosette, with deeply ridged leaves, dark green on top, red underneath, densely covered in purplish hairs. The small white flowers with distinctively narrow petals are also hairy. 
The plant was named after Anthony Lamb, who has contributed much time and effort to begonia research in Sabah. 
Governor Gueritz’s Begonia
One of the most widespread species in Sabah, Begonia gueritziana, is also found in both limestone and non-limestone habitats, but is much commoner. It was discovered by Miss Lillian Gibbs, the first lady, (and a botanist), to climb Mt. Kinabalu in 1910. She named it after the then Governor of North Borneo, Edward Peregrine Gueritz, “for his great kindness and hospitality” during her expedition. 
Sabah also has ultramafic hills, with toxic soils low in nutrients, which many plants do not like, but more than one begonia has exploited this niche in Sabah. 
One of the most unusual is the small, shrubby Begonia vaccinioides, found only on 2570m high ultramafic Mt. Tambuyukon, growing in the stunted, open, vegetation near the summit. 
In fact, I remember seeing plants on an expedition to Tambuyukon, more than thirty years ago, and noticing it as something unusual, as we explored the scrubby vegetation just below the summit. A few years later, a botanist friend, climbing Tambuyukon in search of Rhododendrons, re-found it and collected the specimens from which it was named. 
The name ‘vaccinioides’ comes from the resemblance of its small tough leaves, 2cms, or less, in length, to those of a Vaccinium in the Rhododendron or Blueberry family. 
Mrs Moulton’s Begonia
Other species grow in the montane oak-chestnut forests on sandstone soils, and the Mountain Garden at the Kinabalu Park HQ is a good place to see them. 
At least five species grow here, the commonest being the velvety-leaved Begonia beryllae, with delicate white flowers and dark green pointed leaves, with darker red veins. The pale undersides are also veined in red and young leaves are pink to red as well. 
This species is named for Beryl Moulton, the wife of the curator of the Sarawak Museum, John Moulton, who collected it on a trip to Kinabalu in 1914. 
The Kinabalu Begonia
Kinabalu’s own begonia, Begonia kinabaluensis, has dark green leaves similar to Mrs Moulton’s Begonia, but its stems and flowers are clothed in distinctive bright red hairs, contrasting with the deep green of the leaves and the delicate pink petals. 
The Red-fruited Begonia
Then there is the darker green, velvety-leaved, Begonia erythrogyna, with large clusters of small pink flowers, also common in the Mountain Garden. ‘Erythrogyna’ comes from the colour of the red fruits. 
Ruth Kiew’s Begonia
One of the most beautiful of all Sabah’s species, however, has to be Ruth Kiew’s Begonia, (Begonia ruthiae), another rosette species, but only described in April this year. 
This is found along the trails of the Danum Valley – one of the last remaining areas of unlogged lowland dipterocarp forest in Borneo. 
With its shiny, very dark green, puckered leaves, edged with a pale green rim, contrasting with the delicate white flowers, this species is stunningly beautiful. 
It was named after Dr Ruth Kiew, who has spent many years studying the limestone flora of both Borneo and Peninsular Malaysia and is author of “Begonias of Peninsular Malaysia” as well as a co-author of “A Guide to the Begonias of Borneo”. 
The Iridescent Begonia
The Iridescent Begonia, Begonia rotundibracteata, with a beautiful blue sheen to its leaves was also described only in April this year, and is also from the Danum Valley. 
The iridescent blue sheen develops best in plants in more shaded locations, and may help to reflect the intense light from sun-flecks moving across the dim forest floor, thus preventing damage to leaves used to very low light levels. 
Lack of space does not allow me to include any more species, and my selection has been dictated by available photographs, but the Native Orchid Centres mentioned above have collections of many more species than are illustrated here. 

More than 100 species (134) out of the almost 200 (194) recorded for Borneo, have been described and illustrated in the recently published “A Guide to the Begonias of Borneo”, another of the wonderful, meticulously produced, books on Borneo’s wildlife and its diversity, for which Natural History Publications is so well known. This is indeed a beautiful book showcasing much more of the amazing diversity of Borneo’s wonderful begonias than I am able to do here!

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