Bombacaceae-Connaraceae - SABONET

BOMBACACEAE 

Baobab family 

According to Palgrave’s Tree Book, Rhodognaphalon 

mossambicense is now known as Bombax 

rhodognaphalon (Palgrave, 2002). Brendan Fox and 

Kenneth Robb assert that it is relatively easy to 

transplant this tree in the sandy soils where it grows 

naturally. Move these plants in the dry season, about 

3–4 weeks before the rains start. 

These plants are best propagated from seed. Remove 

seed from its hard outer casing and the fluffy hair in 

which it is embedded. Nick the seed by sandpapering 

the coat and soak the seed overnight or until it starts to 

swell, before placing it in the seedling medium. Sow it 

in well-drained, sandy soil. Germination takes place 

within about 3 weeks. 

The Baobab (Adansonia digitata) is a classical 

example of this group of plants. Although it transplants 

easily, this family is the largest of our African 

succulents and the size can be a limiting factor when 

attempts are made at moving them. 

The procedure for preparing the seed for sowing is 

the same as that for Bombax rhodognaphalon. Adansonia 

seed has a fleshy outer covering instead of the hairy 

covering of Bombax. Chit or nick the seed for quick 

germination. 

Bombax rhodognaphalon tree. (Photo: Kenneth Robb.) 

Bombax rhodognaphalon flower. (Photo: Kenneth Robb.) 

83

BORAGINACEAE 

Forget-me-not family 

Cynoglossum alticola is relatively easy to grow 

from seed, provided the seed is collected before 

animals moving past the plants have a chance to 

disperse it. The seeds are presented high at the 

end of the old inflorescence in grassland. The fruits 

are four nut-like structures joined together. The testa 

bears hook-like bristles or hairs, which enable the seed 

to attach itself to any furry animal that brushes against it. 

In the dormant season, the partially woody underground 

stem can be cut into pieces of about 150 mm. These pieces 

will re-sprout and root in the new season. 

84 

Bombax rhodognaphalon fruit. (Photo: Kenneth Robb.) 

Bombax gnaphalocarpon flower. 

Cordia caffra seedling showing the pleated cotyledon of this genus.

Ehretia rigida is best propagated from seed, and 

although I have not tried cuttings, I suspect that semihardwood 

cuttings will work if taken in spring. Layering 

may work well to propagate Ehretia rigida, as it suckers 

from damaged roots. Cordia is best grown from seed, 

which germinates readily, provided the outer flesh has 

been cleaned off before it is sown. Germination takes place 

in about 14 days or less if the weather is warm and the 

soil is damp. The cotyledons of Cordia caffra have an 

interesting pleated shape. 

I am not familiar with Cystostemon, but I would 

suggest that the plants are visited regularly to monitor 

seed maturity. Collect the seed, remove the testa and 

sow—follow the same procedure as for the other 

boraginaceous species. 

BURSERACEAE 

Myrrh family 

This is a group of plants that is well suited to the harsh 

African continent. Collect seed and remove the red aril. 

Seed germinates within about 14 days. Many species will 

also grow from cuttings, but as I am not familiar with the 

Namibian contingent, this calls for experimentation. 

Species from the extreme desert areas should be treated 

like succulents. Water only when the soil has dried out 

and only in the so-called “rainy season”. Keep the plants 

hot and well-drained, especially if grown in containers. 

Commiphora neglecta is grown from seed in late 

summer. Root cuttings also work well. Break off bits of the 

succulent roots and lay them in river sand—shoots will 

appear in a couple of months. Propagation from normal 

cuttings or truncheons does not work at all. 

BUXACEAE 

Box family 

I believe that this group of plants is probably the 

slowest-growing of southern African woody plants. 

Like Buxus nyasica in Malawi, the two species in 

South Africa that are known to me have a very 

disjunct distribution. Specimens might be found in a 

section of a forest, but not throughout the forest. 

Propagation works best from seed, but the plants grow 

slowly, if steadily. Seed is shiny black and hard-coated. 

I find that seed of Buxus natalensis germinates better 

if the hard coat is lightly scarified with sandpaper. 

Sow the seed in the spring, just as the new growing 

season starts. Germination takes about 2–3 weeks. 

Seedlings develop very slowly and a five-year-old plant 

is not much taller than about 20 cm. 

The seed of Buxus macowanii germinates in about 3 

weeks. There are often many seedlings growing under 

the parent trees. Collect these as “wildings”. The 

leaves of the seedlings up until about 5 years old are 

thin and fine in texture and do not resemble the leaves 

of a mature plant at all. This is also the case with the 

Sneezewood tree, Ptaeroxylon obliquum. 

CAMPANULACEAE 

Bellflower family 

I have grown Wahlenbergia from seed in a humus-rich, 

sandy soil with no fertiliser. I collected the capsules just 

before they split and sowed the seed a day or so after it 

was shed in the early summer. The trays were filled with 

seedling mix and seed was treated like any other fine 

seed. It germinated after about 2 weeks. Young seedlings 

were planted out directly into the open ground. They are 

still growing happily a couple of years later. 

Cuttings should be taken from tips in early spring and 

set in sharp river sand with a mistbed and bottom heat. 

On the KwaZulu-Natal coast, I have been able to split 

or divide a clump and increase the number of plants. This 

method of propagation, however, does not contribute to a 

greater genetic diversity. 

The alpine species of this family form very tight clumps 

and I suspect that cuttings will strike. Make sure that 

there is a growing season ahead before attempting 

propagation by division. 

I believe that seed propagation is a better option, but 

this requires patience and good timing in collecting seed. 

CANELLACEAE 

White cinnamon family 

Warburgia takes root after about 90 days in a mistbed. 

The alternative is to sever roots of a finger-thickness of a 

wild tree with a spade and wait for the tree to produce its 

own new shoots from the cut root. Once the shoot is well 

established, cut it away from the parent plant. This 

method is known as ground or root layering. 

The following observation pointed me in the direction of 

Buxus natalensis fruit with shiny black seed visible inside. 

BURSERACEAE 

85

86 

WARBURGIA SALUTARIS 

by Richard Symmonds & Neil Crouch 

MEDICINAL VALUE AND CONSERVATION STATUS 

The stem and, to a lesser degree, the root-bark of 

Warburgia salutaris (Pepper-bark tree) or isibaha as it is 

known to the Zulu, is one of the most sought-after medicinal 

plant commodities in the southern African traditional 

health care sector (Gerstner 1938; Cunningham 1990; 

Williams 1996; Mander 1997; 1998; Marshall 1998). Its 

near-panaceal qualities were early recognised, not only by 

the traditional users but also by the taxonomist who 

awarded it the epithet “salutaris,” meaning healthful or 

wholesome (Zimmer 1949). Rather than here listing the 

various uses (which range from the relief of mouth sores to 

the treatment of malaria), readers are referred to the 

accounts of Bryant (1909), Gerstner (1938), Gordon 

(1953), Van Warmnelo (1953), Smith (1966), Gelfand et al. 

(1985), Mabogo (1990), and Hutchings & van Staden 

(1994) for such details. 

The widespread popularity of Warburgia has led to its 

extensive over-collection and decline in the wild (Gerstner, 

1946; Gordon, 1953; Cunningham, 1988; Nichols, 1990; 

Hollmann, 1994; Mahende, 1994; Hollmann, 1996; Mander, 

1998; Marshall, 1998; Scott-Shaw et al., 1998) even within 

protected areas (Johnson et al., 1995). This threat to its 

survival has long been recognised, In 1938, Gerstner wrote 

“...there are all over the country only poor coppices, 

every year cut right down to the bottom, used all over 

and sold by the Native herbalists as one of the most 

famous expectorants.” 

A recent global conservation status assessment 

(Oldfield et al., 1998) has accordingly listed W. salutaris 

as a taxon in danger of extinction (EN Alacd), necessitating 

a species-recovery approach to its conservation. 

In light of this, these propagation notes are an attempt 

to document, in particular, the shoot-tip cutting technique 

developed at Durban’s Silverglen Medicinal Plant Nursery 

during the mid-1980s. Following on this success, HL&H 

Mining Timber collected 500 shoot-tip cuttings from 

Silverglen and subsequently rooted them at their Tree 

Improvement Centre at White River (Johnson et al., 1995). 

From this stock, and materials obtained through nature 

conservation bodies, 100,000 plants were timeously 

propagated to promote W. salutaris as Tree of the Year in 

1996 (De Cock, 1995; Esterhuyse, 1996). Several enterprises 

and many individuals, including traditional healers 

(Crouch & Hutchings, 1999), have subsequently benefited 

from access to these young trees. 

Pepper-bark trees have great potential as ornamental 

subjects. With their glossy foliage, fine oval shape, and 

fairly rapid growth rate (especially when established in 

well-composted planting holes), plants make suitable 

screening subjects. They may also be pruned and shaped 

into a hedge. 

Trees (in Durban) planted substantially south of their 

normal distribution range have evidently acclimatised to a 

special feature 

variety of local conditions. This may reflect their tolerance 

toward a broad range of habitats (Marshall 1998). However, 

one can’t help but wonder whether isibaha did at one time 

grow around Durban, but has been driven to local extinction 

through over-exploitation. Such has been the fate of 

Wild Ginger and bushman’s tea. From both a social and 

economic perspective, more of this highly sought-after 

medicinal tree should be planted in park landscape and 

agricultural contexts. 

PROPAGATION 

Propagating from seed 

Growing W. salutaris from seed is possibly the simplest 

and most rewarding way of bulking up this species. 

However, the voracious attentions of fruit flies and monkeys 

make the harvesting of viable seed virtually impossible. 

Fruits ripen between October and December, allowing for 

cleaning and sowing over this period. Before sowing, the 

hard brown-black seeds should be removed from the fruit 

pulp—this process is greatly facilitated by soaking the 

fruits in a bucket of cold water overnight. Seeds should be 

sown in trays on a mixture of sieved compost and river 

sand (1:1) and lightly covered with the same. No pretreatment 

is required, for seeds germinate readily, and start 

emerging after about 21 days. 

Freshly collected and sown seed should give a return of 

80% within 2 months of sowing. Storage of seed is not 

advised for they are probably recalcitrant (seeds that lose 

viability after drying out). Seedlings should be left in the 

trays until they reach 5 cm in height, or the two-leaf stage, 

when they may be re-potted into 1.5 litre bags in river sand 

and compost (1:2). Seedlings established from seed sown 

in December 1996 are now in 6 litre bags and stand 1.5 

metres tall. 

Shoot-tip cuttings 

Propagation using shoot-tip cuttings is currently the best 

way of bulking up Pepper-bark plant numbers, given the 

shortage of viable seed. Long tip cuttings are taken, which 

consist of the top 15 cm length of new apical shoots. 

Depending on the time of the year that the shoot-tip 

cuttings are taken, the tip types will vary from semihardwood 

to softwood. Experience has shown that the 

harder tip cuttings perform better in the Silverglen environment.

top left Ripe fruit (40–50 mm in diameter) of Warburgia salutaris stung by fruit flies; top right Warburgia salutaris; bottom left The beautiful 

trunks of Warburgia salutaris growing in a grove in northern KwaZulu-Natal; bottom right Warburgia salutaris makes a fine hedge. 

Cuttings are best collected early in the morning and kept 

in a bucket of water during the selection and cutting 

process. Cuttings embodying 3–4 nodes (8–10 cm, 

trimmed from the original 15 cm-long tip) are stripped of 

their lower leaves. A clean cut is made at the base of a node 

and the top 3–4 leaves are trimmed to reduce the 

transpirative surface. This cropping reduces the likelihood 

of the cuttings drying out and perishing. The material is 

inserted in washed river sand under mist, and the misting 

timer set to 5-second sprays at 10-minute intervals. The 

mistbeds are bottom-heated at 24 ° C by electrical heating 

cables. Bottom heating improves the strike rate for it 

promotes callusing at the basal node, a necessary step in 

the development of roots. 

Rooting 

Typically, cuttings take between three and four months to 

establish before they are ready to be re-potted into 1.5 litre 

bags of river sand and compost (1:2). Root initiation can be 

evidenced as quickly as 45 days. The rooting period can be 

reduced if rooting hormones are applied, or stricter 

environmental control (for example temperature, mist-drift) 

is exercised at the mistbed site. However, Silverglen 

typically undertakes simple, cost-effective propagation 

protocols —although adequate, these procedures are not 

always the quickest! 

With Durban’s relatively moderate climate, cuttings can 

be taken throughout the year. The average annual strike rate 

of healthy cuttings has been 52%. The lowest recorded 

return is 34% for cuttings taken in June, and the highest 

73% for those cut in March. The growth rate of plants so 

propagated is moderate; cuttings taken from a population in 

Mpumalanga in December 1997 have already been repotted 

in 6 L bags, and presently stand about 50 cm tall. 

These plants are ready to be planted out in Silverglen’s 

Warburgia field genebank, which doubles as the mother 

stock from which the cuttings are taken. 

Many variables are involved in the rooting process, such 

as air temperature, humidity, photoperiod, age and state 

and source of the mother stock and these have clearly not 

been adequately controlled in our “experiment”. However, 

despite this, we feel that the pronounced rooting response 

evident during the months of March and August may be 

linked to the photoperiod, or day-length. These two months 

correspond to the spring (vernal) and autumn equinoxes, 

times of the year when there is as much daylight as 

darkness during a 24-hour period. One may reasonably 

ask—why are the cuttings not “day-neutral”? Are they 

controlling their own response to day length, or are they 

expressing hormones carried over from the mother stock? 

The effects of photoperiod are well researched and 

evidenced in other hormonally driven life processes, the 

most obvious of which is flowering. Although most 

angiosperms exhibit a single flowering period, some offer 

biannual displays. Plectranthus zuluensis is a good 

example, for it flowers well in March (autumn), as indeed 

most members of the genus do, but then produces a 

second display in September over the vernal equinox. The 

prevalent photoperiod, or ratio of light to dark (1:1) likely 

triggers this process. 

87

making the first root cuttings from this species—these 

became the plants at Silverglen. Along the shores of Lake 

St Lucia, the hippo must leave the safety of the water at 

night to move on to the land to graze. Hippos are not 

exactly light beasts and wherever their feet touch the 

damp soil at the lake edge they leave an impression at 

least 100 mm deep. This action of foot-on-soil damages the 

roots of Warburgia salutaris—the animal equivalent of 

the guillotine. Damaged root tips send out shoots and it is 

these “root suckers” that we have up until now used as 

propagules. 

The roots plus the shoots are gently taken out of the 

soil and placed in a mist propagation bed in the nursery. 

After about two months in a mistbed, warmed with undersoil 

heating cables and supplied with a fine intermittent 

mist of water over the foliage, the cuttings are ready to be 

weaned to normal growing conditions. Then after a 

further two months, the 

plants are ready to be 

planted in the open. 

CAPPARACEAE 

Caper family 

In my experience, 

genera such as 

Capparis, Cadaba, 

Bachmannia, 

Cladostemon, and 

Maerua all grow well 

from root suckers, albeit 

slowly. The most 

efficient way to propagate 

any of these 

species is from seed. 

However, birds and 

animals often eat the 

fruit while it is still relatively green. In KwaZulu-Natal, 

fruits will be ripe even though they haven’t yet changed 

colour. Birds are especially good at detecting this. 

The woody capsule of Capparis tomentosa must be ripe 

before the fruit is picked. The seed is contained in a rather 

palatable, mucilaginous, sticky flesh, and needs to be 

removed before the seed is sown. Either abrade the seed 

with a mixture of sand and water, or take the seed and 

place it in about 500 ml of water mixed with a couple of 

tablespoons of sugar. Allow the mixture to ferment for a 

few days. When fermented, the flesh will wash off easily. 

Use one of these methods to clean the seed of Boscia 

albitrunca and B. foetida. Sow the seed as soon as possible 

to maintain its viability—it takes about 3 weeks to 

germinate. Transfer the seedlings to their own packets or 

containers and fertilise with nitrogen. If they do not get 

enough nitrogen, the seedlings soon take on a yellow, pale 

look and stop growing. Even with fertiliser, the seedlings 

seem to stagnate after acquiring about four leaves. In fact, 

the plant is putting all its energy into making a huge 

tuber under the ground. It is important to remember that 

feeding is essential. The plants also like to be fairly rootbound. 

Cleome is best grown from seed. Watch the plants 

closely and collect the capsules just before they split. 

88 

Cadaba natalensis fruit with 

seeds surrounded by orange flesh. 

Cleome seed germinates if sown immediately in disturbed 

soil with not too much fertiliser. Sow seed approximately 

two weeks before the new growing season is about to 

begin. 

CARYOPHYLLACEAE 

Carnation family 

The Carnation family is relatively easily grown in normal 

potting soil with adequate nutrient levels. Seed is the best 

method of propagation—plants produce masses of seed 

that germinates well in seedling trays. They germinate 

within about 3 weeks. I have been able to grow Dianthus 

zeyheri from seed without a problem. The seed capsules 

should be watched carefully and collected as they start to 

split and shed their seed. Dry the capsules in a tray lined 

with newspaper in a dry, shady area. Sow the seeds 

immediately as they are shed. In KwaZulu-Natal, Dianthus 

flowers in early summer and the seed is ready to sow 

in about 6 weeks. This gives ample time for the young 

seedlings to germinate and become established before 

winter. Leave the seedlings in their trays for the first 

season and prick them out in the following summer. 

Other propagation methods for Dianthus and Silene 

include tip cuttings and division. 

The species of Dianthus that are endangered should be 

propagated as early in the season as possible to allow 

enough time for the seedlings to become established 

before winter or the dry season. 

CELASTRACEAE 

Staff-tree family 

This family is relatively easily grown from seed. It is 

widely distributed in southern Africa. 

In my experience, one should wait until about a third of 

the visible fruit is beginning to split open. Pick a branch 

that is full of fruit and hang it over a tray or box to catch 

the fruit when they drop. The seed is usually covered by a 

fleshy white, yellow, or orange aril. Remove it and sow 

immediately. (I suspect that this family has recalcitrant 

seed.) The seed germinates within 2–4 weeks after 

sowing. Use a well-drained, inert seedling mix. Start 

adding nutrients only once the little seedlings have been 

pricked out into trays or bags. I prefer small containers— 

they provide better support for the roots, which are weak 

initially. Although not rapid growers, the plants do well 

once placed in open ground. These trees and shrubs 

generally tend to produce large amounts of seed, so I 

haven’t yet attempted to grow them from cuttings. 

CHENOPODIACEAE 

Goosefoot family 

This family is one of extremes. We have many introduced 

weedy species, as well as our own, native species. They 

live at the remotest edges of plant growth, either in semidesert 

or as dwellers of the most severe salt marsh and 

semi-marine conditions. I have no experience in growing 

any of these plants and would like to know of others who 

might have grown them. My only advice is to try cuttings 

of the desert species as these may well root. I would 

suggest the focus is on protecting the habitat of the salt 

marsh species, rather than ex situ propagation attempts.

See if you can collect seed to sow in suitable habitats, 

undisturbed by humans. 

COMBRETACEAE 

Combretum family 

My experience with this family is that it is best grown 

from seed. The seed tends to be fairly highly parasitised. 

Collect as much fruit as you can from as many trees as 

you can. This takes time and energy, but is worth the 

trouble, ensuring that at least some would be free of 

parasites. Gather the fruit in a sack and crush all the 

wings. This crushing makes the seed less bulky and easier 

to sow in large seedling beds. Seed germinates within 

about 14 days, but depending on ambient temperature, 

this may be as short at 7 days or as long as a month or 

more in colder areas. 

Pteliopsis is sown in the same way and prefers sandy, 

nutrient-poor soils with plenty of organic matter. Growth 

is slow in containers, but rapid in the ground. Do not be 

concerned if the plants grow sideways! The branches will 

pick up once the lignin is set down in the winter resting 

months. These plants have a weeping habit and do not 

need to be pruned too early in their lives. 

In the case of Combretum and Terminalia, carefully 

remove the actual seed kernel from the outer casing and 

sow this. In this way, the seed sown is of good quality and 

seed germination happens quicker. By leaving the outer 

casing around the kernel, a high degree of seed predation 

is possible. The Kew Millennium Seed Bank staff X-ray 

their seed to check for fertile and infertile seeds. It is 

astounding how the huge cotyledons of the genus 

Combretum can be compressed into one seed. 

The rule of thumb I have employed 

regarding these two genera is that 

if I want 100 plants, I sow 

1,000 seeds. The proportion of germination success is 1:10. 

Always collect more seed than needed, because it is better 

to grow more plants than have too few. Furthermore, 

when huge amounts of energy and time are spent mounting 

a collecting expedition, it is unlikely that one will 

return to the location to collect more seed in the near 

future. 

Combretum seeds. 

COMBRETACEAE 

ARECACEAE 

Gymnosporia grandifolia fruit dehiscing. The aril surrounding the 

seed is visible. 

89

CONNARACEAE 

Itch-pod family 

In some books, Rourea minor is the synonym of 

Santaloides afzelii (Beentje, 1994). Cnestis polyphylla and 

Rourea species are scandent shrubs, rather than trees. 

The tree-forming species perform best from seed, but seed 

may not be produced each season. Cnestis, for example, 

needs full sun to flower. The fruits of this family resemble 

legume pods. The seed is usually black with a yellow 

fleshy aril, indicating that it is recalcitrant and therefore 

important to sow immediately. Remove the outer skin 

from the seed before it is sown. 

I have no experience regarding propagation from 

cuttings. 

Cnestis polyphylla fruit. 

90 

INTERESTING FACT 

I have observed Cnestis plants growing vigorously in a forest, but 

the leaves were in the understorey and it never flowered. The next 

season, when I visited the same Cnestis plant, there were masses 

of flowers and fruit. Sunlight, caused by an opening in the canopy 

created by a collapsed tree, was responsible for the sudden burst of 

flowers and fruit.

Bombacaceae-Connaraceae - SABONET

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