BotSoc Beyond Botanical Gardens: Exploring Microhabitats in Overberg Renosterveld

One of the things that the Botanical Society of South Africa is most famous for is its close relationship with South Africa’s National Botanical Gardens. Some of our bigger branches such as the Kirstenbosch and Bankenveld Branches have their homes at gardens. However, this is not the case with all branches of this extraordinary nationwide organisation. Some branches, such as our Southern Overberg Branch, are in areas that may not have their own botanical gardens but are known for their extraordinary and unique biodiversity. The Overberg area is also home to several fantastic conservation organisations that work tirelessly to conserve threatened habitats in this area. We went to visit our partners at the Overberg Renosterveld Conservation Trust (ORCT) to find out more about what makes this extraordinary vegetation that forms their main conservation focus unique.

Above: The beauty of Overberg Renosterveld in the Eastern Ruens at the ORCT’s Haarwegskloof Renosterveld reserve.

The renosterveld of South Africa’s Overberg region is one of the most species diverse Mediterranean type shrublands. It is also one of the most threatened and under-researched. One of the factors that has caused the evolution of such high levels of diversity and species turnover is the presence of high levels of habitat heterogeneity and many different types of microhabitats within the ecosystem. The levels of diversity and endemism associated with this is something that we are only just starting to fully understand about Overberg Renosterveld.

Above: Succulent species often are well adapted to life in rock crevices in Overberg Renosterveld.

So what does this all mean? When there is habitat heterogeneity in an ecosystem it means that across a relatively small area there is considerable variation in the specific ecological conditions that lead a certain plant or animal calling a place home. Soil chemistry or structure, availability of water, different levels of light or shade from the sun and other factors influencing growing or living conditions may vary to an unusually great extent in this environment. If a certain organism requires a specific set of these conditions to thrive, this is known as a habitat niche. Some organisms may live happily in a wide variety of different habitat conditions, others are adapted to one set of specific needs that can be only found in a select few places.

Top: Polhillia curtisiae named after the director of the ORCT, Dr Odette Curtis-Scott for her services to renosterveld conservation. Above: Endangered Gladiolus vandemerwei growing in a shale rock wall in Overberg Renosterveld.

Where habitat conditions in a small area differ from the surrounding ecosystem, acting as home to a unique assemblage of flora and fauna, it is known as a microhabitat. This is a common phenomenon in Overberg Renosterveld and can manifest in various different ways. The unusually common occurrence of microhabitats has meant that this extraordinary and biodiverse ecosystem is home to an unusually high number of endemic species. The word ‘endemic’ means that the organism being described only lives in one place, and is found nowhere else in the world.

Above: Quartz patches within Eastern Ruens Shale Renosterveld in the Overberg.

One of the most noteworthy examples of unique microhabitats within Overberg Renosterveld are the patches of white quartz found within the Eastern Ruens. These have similarities to the quartz fields found in the Knersvlakte in Namaqualand and in the Klein Karoo, but are home to a unique assemblage of endemic species, many of which are now highly threatened in the wild after their homes have been ploughed up for agriculture and lost forever. The Eastern Ruens quartz patches had previously been dismissed as having relatively low levels of biodiversity, but more recent research has revealed no less than six new species endemic to this unique habitat.

Above: The beautiful and newly described quartz patch endemic Aspalathus quartzicola. 

It has often been said that, despite the fact that renosterveld vegetation forms part of the Fynbos Biome, it actually has a greater ecological affinity with Karroid vegetation types due to its large succulent component. Many of these succulent species have found weird and wonderful places to live within this vegetation type. Succulents are typically associated with hot and dry conditions, but in fact many actually prefer to grow away from the worst of the sun’s heat. Some species might grow inside the large tussock grasses so typical of Overberg Renosterveld. Others are commonly found growing underneath larger bushes. Large outcrops of shale where the softer strata have been weathered away provide deep crevices where both succulents and many bulb species may grow.

Top: Unusual form of Nerine humilis Above: Spectacular Gasteria flowers.

In the Eastern Ruens there are also outcrops formed from quartz geology. These quartz koppies often have a unique array of different species. The ORCT discovered that one of these was the only remaining home for a unique form of the autumn flowering Nerine humilis. This particular form has unusually long styles and filaments, thought to be an adaptation to a specialist pollinator, likely a long-tongued fly. However, sadly despite extensive pollinator observations, the pollinator was not seen and the blooms of these form are no longer being pollinated here. It is thought that the long tongued fly that pollinates this form is sadly now extinct in the area.

Above: Sadly illegal destruction of renosterveld vegetation is still a common occurrence, driven by a desire to make more money from agricultural land and increasing size of farm machinery.

These stories highlight the uniqueness of Overberg Renosterveld, as well as its fragility as it is becoming increasingly fragmented within an intensively farmed agricultural landscape. In the past many of the rocky areas that form the unique microhabitats within this vegetation type have remained safe due to the difficulty in being ploughed out. But now with increasingly large farm machinery these small pockets of vegetation are being illegally bulldozed out. The sheer complexity of this habitat makes it highly challenging, if not impossible to restore once it has been destroyed. So spare a thought for this unique and extraordinary habitat and lend your support to those at the Overberg Renosterveld Conservation Trust who are working tirelessly to conserve it in perpetuity.

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Wildflower Wonders: Where to find the best blommetjies this Spring

This winter, after three long and dry years in succession, the rain came. The drought’s impact has been pervasive, affecting the economy, agriculture, tourism and much more. Above average rainfall this June has provided some respite and improved dam levels, but we are far from out of the woods yet.

However, good winter rains are making it increasingly likely that we will have some wonderful displays of wildflowers this spring. Already there are beautiful carpets of Oxalis giving their winter display along our road verges. We have hand-picked for you a selection of our favourite places to go and experience the Cape’s world famous wildflower displays. All of these stunning places are within five hours drive of Cape Town, easily accessible on a weekend for those of you with limited time available.

NAMAQUALAND 

Nieuwoudtville

The small town of Nieuwoudtville lies at the top of the Bokkeveld Escarpment, five hours drive north along the N7 from Cape Town. It is not without reason that it is known as the ‘Bulb Capital of the World’. The town is home to Hantam National Botanical Gardens (NBG) one of South Africa’s newest NBGs, run by the South African National Biodiversity Institute (SANBI). Hantam NBG is 6000 Ha in size encompassing Nieuwoudtville Shale Renosterveld, Nieuwoudtville-Roggeveld Dolerite Renosterveld and Hantam Succulent Karoo.

This unique range of untransformed habitats makes this the place to see many of the rare and special plant species known from the Bokkeveld Escarpment. The garden has nine different hiking trails that allow those of differing levels of fitness to explore as they please. Members of the Botanical Society enjoy free entrance to this and all of South Africa’s NBGs. Additional tourist information for the area can be found at www.nieuwoudtville.com

WEST COAST

West Coast National Park

West Coast National Park lies on the coast between the small towns of Yzerfontein and Langebaan just 1.5 hours drive north of Cape Town. The park is a mix of Strandveld and Hopefield Sand Plain Fynbos.  During August and September visitors to the park are rewarded by the most spectacular displays of flowers in the Seeberg and Postberg sections of the Park. For the more energetic the two day overnight Postberg hiking trail can be done, with an overnight stop (bring your own tents) at Plankiesbaai. Bookings and tariff information can be obtained from Geelbek Information Centre on 022 707 9902. Entrance to the park is R76 for South African Nationals and residents (with ID) and free for Wildcard Holders.

Tienie Versfeld Nature Reserve

Tienie Versfeld Nature Reserve is 20 Ha in size and found just outside the Swartland town of Darling, an hour north of Cape Town. The reserve was formerly part of a farm that was donated to the Botanical Society by Marthinus Versfeld. Marthinus’s sister Muriel was one of the founder members of the Darling Wildflower Society. The reserve is open all year round, but the most spectacular blooms can be seen during the spring season from August to September. Entrance to the reserve is free.

Waylands Farm Wildflower Reserve

Also near the beautiful town of Darling is the fantastic Waylands Farm Wildflower Reserve. The reserve was founded by Fredrick Duckett in the early 1900s and is home to more than 300 different plant species, many of which are geophytes. The reserve forms an integral part of the farm and is grazed from late November to the end of April each year. The spring flower season reaches its peak from the end of August to early September.

CEDERBERG 

Ramskop Wildflower Garden

Three hours drive north of Cape Town on the N7 is the small town of Clanwilliam, which lies at the foot of the Cederberg Mountain chain. Adjacent to the municipal campsite on the banks of the Clanwilliam Dam is the beautiful Ramskop Wildflower Garden. There are more than 300 species of different wildflowers to be seen, and spectacular views down over the dam and up to the Cederberg mountains beyond. Entry is R25 and the gardens are open until 4:30pm during August and September. (Info: 027 482 8000).

Biedouw Valley

 

The Biedouw Valley is one of the Cederberg’s hidden wildflower gems. It can be reached either via Calvinia or the Pakhuis Pass from Clanwilliam. The Biedouw River is one of the tributaries of the Doring River. The valley is bounded by the Biedouw Mountains to the north and the Tra Tra Mountains to the south. The name ‘Biedouw’ refers to the common plant name ‘Bietou’, although there are several plants that go by this name so it is not clear to what species the name originally refers. In spring local farmers restrict livestock grazing in the area to further enhance the stunning wildflower displays. 

CAPE TOWN  

Rondebosch Common

 

Rondebosch Common lies at the heart of Cape Town’s Southern Suburbs. This 40 Ha site is of international conservation importance, being one of the last fragments of Critically Endangered Cape Flats Sand Fynbos, a highly biodiverse vegetation type that only occurs in the greater Cape Town area. It is home to around 250 plant species.

The site is under the custodianship of City Parks and their work is supported by the Friends of Rondebosch Common, affiliated with the Wildlife and Environmental Society of South Africa (WESSA). Each spring the Friends run a series of walks lead by dedicated volunteers to see the spring flowers on the Common. All are welcome and becoming a Friend is encouraged to support the valuable conservation work taking place. More information can be found on the Friends’ Facebook group.

https://www.facebook.com/groups/Friends.of.Rondebosch.Common/

 

Out of the dust: A mass flowering of Brunsvigia bosmaniae

The small Namaqualand town of Nieuwoudtville lies on the Bokkeveld Escarpment, just north of the border between the Western and Northern Cape. It is reached via the Vanrhys Pass, named after Petrus Benjamin Van Rhyn who was a clergyman and member of parliament in the old mission settlement of Troe Troe. The pass winds its way up from the quartz gravel plains of the Knersvlakte to the high altitude renosterveld and fynbos of the escarpment, home to many rare endemic plant species.

It is not without reason that Nieuwoudtville is known as the ‘Bulb Capital of the World’. In spring the veld comes into bloom in a plethora of colour, drawing visitors from all over South Africa and beyond to see the spectacular displays. Here BotSoc partner the South African National Biodiversity Institute (SANBI) manages Hantam, one of the country’s newest National Botanical Gardens (NBG). Hantam NBG is more than 6000 Hectares in size and conserves habitat of Nieuwoudtville Shale Renosterveld, Nieuwoudtville-Roggeveld Dolerite Renosterveld and Hantam Succulent Karoo. Visitors to the garden have a choice of nine different walking trails to explore the garden, of differing lengths to suit all levels of fitness.

The last couple of years has seen South Africa experience the worst drought in living memory. Water has become a commodity all too precious and the winter rain that brings the veld into bloom in spring did not come. The veld remained dry and the bulbs remained dormant,  with the drought impacting on livelihoods in farming, tourism and on wildlife.

However, as the hot and desperately dry summer ended, autumn arrived at the Cape. And this autumn the rain came. Ephemeral streams long dry started to flow and green returned to the veld. The rain triggered the coming of an extraordinary phenomenon, last seen in Nieuwoudtville four years ago. On municipal land managed by Hantam NBG and the adjacent WWF Wildflower Reserve, the previously dry ground began to crack, and flower buds began to emerge.

These flowers are the huge autumn flowering geophyte Brunsvigia bosmaniaeor Maartblom, a member of the Amaryllidaceae family. This species is distributed from southwestern Namibia southwards to Tygerberg north of Cape Town and inland to the Roggeveld and southern Tanqua Karoo. It is most common around Nieuwoudtville and Vanrhynsdorp where it occurs in huge and dense colonies. The type material was first collected near Piketberg in 1927 but did not flower in cultivation until 1932.

Huge moisture filled bulbs allow this plant to survive long periods of drought. Their flowering is triggered at the end of summer when intense thunderstorms arrive following incursions of tropical air that arrive in Namaqualand from the north. These perfect conditions to trigger flowering do not happen every year: These Brunsvigias often have a long wait to reproduce.

As the days go by and the Brunsvigias come into flower, the veld slowly turns an intense shade of pink. The blooms are the size of footballs. Word spreads and visitors come to Nieuwoudtville from far and wide to see this spectacular floral display. The display is fleeting, lasting around a fortnight. As flowering ends the infruitescences dry out and come adrift from the bulb, allowing the wind to blow them across the landscape, distributing the seeds as they go. Meanwhile, flowering done, the huge leaves start to emerge, and will remain until the bulb goes dormant during the summer months. The Brunsvigia bosmaniae of Nieuwoudtville must now wait, until the next autumn thunderstorms come.

Amazing Agapanthus: The Flower of Love

Written by Zoe Poulsen

Visitors to Kirstenbosch in the last couple of months will not fail to have noticed the spectacular blue and white flowers through the gardens flowering at present. These belong to members of the genus Agapanthus which bring on a stunning summer show for all to see. These gorgeous blue flowers are world renowned and globally cultivated, prized as both a garden plant and cut flower.

 

Above: Agapanthus praecox ‘Purple Delight’

The genus Agapanthus belongs to the family Agapanthaceae. The genus was first described by L’Heretier in 1788. It was initially placed in the Liliaceae family, then moved to Amaryllidaceae. It was then moved to the Alliaceae family alongside the genus Tulbaghia but was later moved back to Amaryllidaceae and then latterly placed in its own family. This is because the compounds responsible for the strong garlic aroma that typifies other members of the Alliaceae family are notably absent from Agapanthus.

The genus name Agapanthus is derived from the Greek words ‘Anthos’ meaning ‘love’ and ‘Anthos’ meaning flower. Members of the genus are also known as the Blue Lily, African Lily or strangely in Europe and America as the Lily of the Nile. In the case of the latter it is likely that this name has its origins in a miscommunication about where the plant material originated from when it was first brought to Europe from South Africa. In Afrikaans they are known as Agapant, in Xhosa they are called isicakathi and in Zulu they are known as ubani.

Above: Agapanthus ineptus subsp. pendulus ‘Graskop’

There are currently around ten different species of Agapanthus recognised and the most commonly cultivated of these is Agapanthus praecox. There are three different subspecies and a plethora of different cultivars and hybrids available in various shades of blue, purple and white of various different sizes. In the wild Agapanthus praecox subsp. praecox is found in the Eastern Cape. Agapanthus praecox subsp. orientalis is also found here but is also distributed further north into Kwa-Zulu Natal. The relatively diminutive Agapanthus praecox subsp. minima is distributed from Knysna to the Eastern Cape. It is relatively easy to grow, tolerating even very poor soils and strong coastal winds.

Plants of Agapanthus praecox are often misidentified as Agapanthus africanus. This species is in fact much smaller and far more difficult to cultivate. It grows on rocky sandstone slopes from the Cape Peninsula eastwards to Swellendam in the eastern Overberg from sea level to 1000m asl where they even experience frost and snow from time to time. It is more commonly known as the Cape Agapanthus or Kleinbloulelie in Afrikaans. Flowers are most commonly deep blue but rare white forms are occasionally seen. They are pollinated by wind, bees and sunbirds. In 2003 a new paper was published lumping Agapanthus walshii with Agapanthus africanus leading to them being recognised as two different subspecies.

Bee visiting Agapanthus praecox at Harold Porter National Botanical Gardens

Despite being poisonous and causing mouth ulcers when ingested, members of the genus have a significant variety of different medicinal uses. It is considered to be the plant of fertility and pregnancy. In Xhosa culture a necklace of the roots is worn as a charm to bring healthy, strong babies into the world. Zulu people use the plant in the treatment of heart disease, coughs, colds and chest pain. It is also used to ward off thunder by those scared of thunderstorms. It is also sometimes used as a love charm.

So come visit us at Kirstenbosch and see the stunning blooms of the ‘Flower of Love’. Membership of the Botanical Society of South Africa gives you free unlimited entrance to all our national botanic gardens. So why not sign up or gift a membership to a friend or loved one? We look forward to welcoming you.