STREPTOCARPUS:
A BRIEF STUDY IN MPUMALANGA AND THE ROYAL NATAL NATIONAL PARK


An article by Lynne Dibley recounting her hunt for Streptocarpus plants in South Africa during January 1997.

Click on the thumbnails to see larger images.
Text and Images 1999 L.Dibley/Dibleys Nurseries


About a third of all the known species of streptocarpus (around 40) are indigenous to South Africa. The genus streptocarpus is limited in its geographical location to shaded areas which have dry winters but have high levels of rain during the summer. I had been in touch with collectors and growers of streptocarpus plants in South Africa. It was from one of these that I received some bad news about streptocarpus. In the latest red data list of threatened plants in South Africa, there were ten streptocarpus species mentioned. The habitat of this genus is being destroyed by agricultural methods, timber farming and the introduction of non-native plants.

In my quest to see some of these plants growing in their natural habitat, I flew into Johannesburg and then headed east to the Mpumalanga province (figure 1). Approximately ten species have been recorded in this area.

 plate 1

plate 2

MPUMALANGA PROVINCE

I travelled five miles from Sabie into an indigenous forest and followed a trail, the first section of which was fairly popular with tourists. After a fork in the path someway along the trek, I saw on a rock to my left, several small streptocarpus unifoliates (plate 1). With mounting excitement I explored other rocks and trees and discovered more and more plants. They all looked similar: unifoliates with a reddish purple underneath (plate 2). The plants to my right, a couple of metres from the path, had a few flowers and ripe seed pods. All the plants were unifoliates with no secondary leaves growing from the petiolode of the main leaf and the ripe seed capsules were attached at the base to a leaf that had almost entirely withered away. They were growing close to the stream, under heavy shade on moss covered rocks and trees that faced southwest.

 plate 3

I believed these plants to be S. pentherianus. They had only one flower open on an inflorescence at any one time. The leaves were approximately 190mm long and 150mm wide; not the largest of unifoliates, some of which can grow to over 400mm in length. One particular plant I noticed was heavily infested with aphids. It is nice to know that plants suffer from the same problems in the wild as they do back home!

At Bridal Veil Falls I found a group of rosulate streptocarpus, none of which were in flower. The plants varied in size from those with two or three leaves which were about 30mm to 50mm long, to huge plants that consisted of over fifty leaves, with a diameter of approximately 600mm (plate 3).

I continued to find more and more S. pentherianus which tended to grow in heavily shaded areas. The rosulate species, however, tended to grow on vertical rock faces in south facing clearings.

 plate 4

The path became continually steeper until I turned northwards and following the course of a stream, entered a clearing with a huge waterfall. What a beautiful sight! A couple of metres up the fall, there was a clump of streptocarpus in full bloom. These were a rosulate variety with cornflower blue flowers. Each flower had seven deep purple veins and a yellow bar radiating out of the corolla tube (plate 4). This had to be S. cyaneus.

The average rainfall in this area is 1269mm per year, with the highest rainfall in January and February (170mm-190mm per month). Mist is a common sight in the summer and snow often occurs on the mountain tops during the winter. The temperature of this area ranges from 26.3C in December to 3.4C in June. streptocarpus are very well adapted to the wet summer and dry winter conditions which they encounter in this area of South Africa. During the winter, the plants produce an abscission layer in order to minimise water loss and reduce the photosynthesis area. The plants wilt during a drought and recover when the rains come.

 plate 5

BLYDE RIVER SPORT NATURE RESERVE

A few days later I journeyed to the Blyde River Sport Nature Reserve, an area of outstanding beauty. At an altitude of 2km, the land to the east suddenly drops away by a kilometre into a forested canyon. In certain areas, especially at God’s Window, you are able to see kilometres into the distance - right over the Kruger National Park and into Mozambique. Fortunately, it was an exceptionally clear day (plate 5).

 plate 6
A short walk from God’s Window, I found a group of plants, possibly S. parviflorus (plate 6). These plants, which were growing in a cool, damp gully in dappled sunlight, varied slightly to those already documented in this area. The plants had vigorous vegetative growth with up to three leaves, growing to a length of 750mm. The streptocarpus plants recorded previously were white or faintly violet, with seven violet lines and a faint yellow bar in the throat, on several flowered inflorescences. The one plant in bloom had white flowers, with two rows of purple spots over a yellow bar in the throat of the corolla. Both S. parviflorus and S.cyaneus are present in this area, as S. cyaneus tends to grow northwards from this point and S. parviflorus grows southwards.

 plate 7
The fact that each species has many forms makes it difficult to draw a distinction between the sub-species. Perhaps they are still changing and hybridising. This could explain why the colony at God’s Window appears to differ from its description forty years ago. One young plant with only one leaf, which had produced one inflorescence, was beginning to grow a second leaf from the base of its original leaf at its petiolade (plate 7).

 plate 8 plate 9

plate 10

NATAL DRAKENSBERG

Our first finding of streptocarpus in this area was on a footpath known as Otto’s Walk. This variety was a unifoliate, coloured beetroot red on the underneath of the leaf (plate 8). There were very few plants in this group and only four of them were mature enough to flower. The fact that the flower was small (about 11mm in width) and that the upper lobes were slightly reflexed indicates that this species may have been S.pentherianus. On the other hand, the capsules were up to 57mm long (plate 9), which may suggest that it was in fact S. polyanthus ssp. verucundas, which has only previously been recorded growing nearer the coast. although S. polyanthus ssp. dracomontanus, with its 2-3 leaves is more often associated with the area, the fact that these plants were definitely unifoliates (plate 10) strongly suggests that this was indeed S. polyanthus ssp. verucundas.

My last day in South Africa was probably the most rewarding day for seeing streptocarpus plants. In one days walk of 14km, not only did I find S. polyanthus ssp. verucundas again, but I also found three other species.

 plate 11

plate 12

My walk started in a well defined forest path. I soon came across some unifoliate streptocarpus growing on the rocks and soil embankments (plate 11). The leaves had a maximum length of 136mm. The first few plants were without flower, but I soon found plants in bloom. Yet again they were S. polyanthus ssp. verucundus, with many young leaves competing with the moss for anchorage and light.

Begonia sutherlandii , with their orange flowers, were very common at this point. It was interesting to note that their leaves were scarred from mildew, whereas the streptocarpus were not afflicted in the least (plate 12).

 plate 13

plate 14

The path soon left the first forested area and followed the Tugela River upstream, slowly climbing in open savannah which had many Protea trees (plate 13). I passed through several wooded valleys during the day to reach my destination (plate 14). In the second wooded valley, there were several unifoliate plants growing on the soil embankment, but with no flowers.

Although the dimensions of the leaves were similar to the previous unifoliates, these had a pale green underneath with very thin blades and seed capsules which were a maximum of 25mm long. I presumed that this was not S.polyanthus, and hoped that I would find more of this species in flower to enable me to identify it.

 plate 15 plate 16

 plate 17
 plate 18

As we went deeper into the forest we were greeted with a carpet of S. gardenii, covering all the large rocks and forest floor (plates 15 and 16). There were literally hundreds of plants of all ages. The microclimate in this particular area obviously suited them. There was very little direct sunlight coming through the trees above, and although there was not a stream here, the rocks were damp enough to be covered in moss (plate 17). The temperature in this area had been recorded at 2.9C in the previous two winters and there was also a sharp decline in rainfall compared to the summer months.

As I came closer to the edge of this clearing, I again saw a few unifoliates with paper thin leaves, this time one was in bloom. It had very small white flowers (plate 18). The corolla was completely different in shape to S.polyanthus. Instead of the corolla tube being sharply reflexed then directed forward, it was an open straight tube with all the corolla lobes being equally reflexed.

 plate 19

plate 20

plate 21

The next wooded valley brought vast quantities of S.gardenii (plate 19). I also found a mixture of unifoliates: a large quantity of a thin leafed variety (which may have been S. pusillus) growing between boulders and a few of the thicker leafed S. polyanthus ssp. vercundus. Most of the unifoliates had finished flowering. The S. pusillus had large numbers of short seed capsules per plant, suggesting that they are probably very floriforous (plate 20).

From this last wooded valley the path climbed steeply, still following the Tugela River, until I entered the Tugela Gorge (plate 21). As I reached the top of my hike, the weather was beginning to break with the occasional clap of thunder.

The Gorge is carved out of sandstone and has vertical sides with the occasional waterfall tumbling down from above. The falling water joins the river flowing below amongst the many large boulders. There were a small number of plants, including a few streptocarpus species rooted amongst the rocks a little way away from the water. There were S. polyanthus ssp. dracomontanus, with very thick, rigid leaves. The flowers were a rich blue, with a yellow eye and about 6mm wider that S. polyanthus ssp. vercundus (large plate at top of page).

It was time to turn back. On the return journey the rain started pouring down, to hasten me on my way.

The habitats of all the streptocarpus that I had seen were roughly the same. None of the plants were in direct sunshine; either sheltered by the rock on which they were growing, or in deep shade under trees. They were mostly epiphytic, or liphophitic, showing that in a damp atmosphere, streptocarpus plants do not need soil to grow, allowing the roots to act as a form of anchorage.

I feel very fortunate to have seen these beautiful plants growing in their natural habitat. My trip has enhanced my knowledge of streptocarpus plants and their natural habitat, which will help me to understand their growing requirements to a greater degree.

 


BIBLIOGRAPHY

Streptocarpus: An African Plant Study, Hilliard, O.M & Burtt, B.L.; University of Natal Press. 1971.


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