PlantLife Volume 51.3 July 2021. Two rare and endemic Brachystelmas of southern KZN

 Notes on two Brachystema species from the Pondoland Centre of Endemism

Text by Ralph Peckover, Photos by Ralph Peckover and Graham Grieve

Brachystelma tenellum – possibly the rarest of Brachystelma species - has been of interest to me for many years, beginning when plants were found at the type locality at Oribi Gorge near a rocky promontory called “Gibraltar” in 1992.

In an article in Veld & Flora in 2014 (volume 100(3)) I reported on the apparent demise of the plants at the type locality (a single plant was recently found here) but fortunately another site near Izingolweni (Ezinqoleni) was found together with Pondoland Custodians of Rare and Endangered Wildlife (CREW) in December 2013. Here a total of 15 plants were found after a thorough search. Unfortunately, 15 plants would not constitute a viable population as these numbers are on the very low side.

An opportunity arose on the morning of 23 December 2020, again with the same CREW group, to visit a farm bordering the Oribi Gorge Nature Reserve where there is a strip of grassland alongside the cliffs above the Umzimkulwana River. The day was perfect despite the not-so-great weather forecast. 

 

Brachystelma australe

 

Brachystelma australe flower with broken concentric lines in the corolla bulb. Linear leaves. Oribi Gorge. (RP)

 

Brachystelma australe flower with concentric lines on inside of corolla bulb. Linear leaves. Oribi Gorge. (RP)

 

The first Brachystelmas found on this occasion were B. australe and there were hundreds in the area. These plants grow on well drained, usually sandy soils near the edge of sandstone platforms overlooking the Mzimkhulwana and Mtamvuna river gorges in KZN.

This Brachystelma has deciduous long, straggly decumbent stems with a single flower at each leaf node. The leaves can be linear to almost elliptic. The plants have a small underground caudex (approximately 20mm x 12mm) that enables them to survive periods of drought, particularly as these shallow sandy soils dry out quickly.

 

Brachystelma autrale flower with shallow corolla bulb and fine spotting. Linear leaves. Oribi Gorge. (RP)

 

Brachystelma australe flower with fine spotting and hairy corolla bulb. Linear leaves. Umtamvuna NR. (RP)

 

Brachystelma australe flower with dark centre and fine hairs on the inside of the corolla bulb. Linear leaves. Umtamvuna NR. (RP)

 

Flat sandstone sheets which are home to many Brachystelma australe plants. The Oribi Gorge NR lies to the left of this escarpment. (RP)

There is considerable variation in the flowers of Brachystelma australe around Oribi gorge on the Mzimkhulwana river in comparison with those seen at the Umtamvuna nature reserve on the Mtamvuna river. Plants from Oribi Gorge have flowers that are hairless on the inside of the corolla bulb while those from Mtamvuna are mostly larger and have hairy flowers. Both areas have flowers with concentric black lines or varying degrees of spotting on the inside of the corolla bulb. From personal observations at Umtamvuna, these plants also had mostly linear leaves whilst at Oribi both linear and elliptical leaves are encountered.

 

Brachystelma tenellum

Later in the morning my eyes found the first of the elusive B. tenellum plants in reasonably deep sandy loam soil - unlike the very shallow soils on sandstone pavements which was typical at the other two sites. The small size of these plants – circa 30 mm tall - and cryptic coloration of a dull purple make them very difficult to spot. The tiny flowers are even more difficult to see without going down on hands and knees.

 

A small Brachystelma tenellum with purple leaves. Two Eriospermum mackenii plants also present (RP)

Brachystelma tenellum plant in the open. A flower at the lower centre of the photo (RP)

 

A flowering Brachystelma tenellum with purplish-green leaves (RP)

 

The very small (and unobtrusive) flower of Brachystelma tenellum well illustrated for size (GG)

Brachystelma tenellum flower (GG)

After more eyes were brought into play, at least 100 plants were found in an area of around 1000 m² in the easterly section of the visited area. I believe there are two reasons why this habitat is suitable for this species:

1. There are annual regulated fires through this area. From information received, the grassland was burnt approximately six weeks before our visit. Such fires remove excess dead grass material and remove shading of these very small plants. Burning also supplies some growth nutrients from the ash.

2. Cattle frequently graze this area which further reduces any shading by grasses. As the grass cover is so sparse, few cattle visit the area here but graze more on the thicker grassed areas, so no trampled plants were observed.

My theory as to why there are so few plants at the other site at Izingolweni, is that this area has not been burnt for many years, meaning more plants would succumb at the seedling stage and be shaded out by the moribund grass in the area. In all visits to this site, no evidence of burning has ever been seen.

Some photos at this new site show how the flowering plants appear very healthy owing to the actions of people and cattle—in this case benefiting this species. 

 

Typical habitat where Brachystelma tenellum were found. 4 plants can be seen in the lower centre of the image. Very sparse grass cover allows the plants to grow optimally. (RP)

 

About the author:  Ralph is a horticulturalist who worked for a period for the CSIR as well as serving as a Developmental Agriculture advisor in the former homelands. For the last 20 years he has worked as an independent inspector for the certification of organic farmers in southern Africa. He is the author of numerous articles on plants including the publication of the descriptions of 16 plant species new to science, including several Brachystelma species.